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HomeMy WebLinkAboutLetter (electrical codes) - 04/11/1995 CITY HALL 215 Church Avenue P. 0. Box 1130 Oshkosh, Wisconsin 54902 -1130 City of Oshkosh April 11, 1995 Nancy Lovgren 1917 Michigan Street Oshkosh, WI 54901 RE: Copies of the Electrical Code you requested Enclosed are copies of ILHR 16.09 Inspection and Maintenance. NEC 110 -22 Identification of Disconnect Means NEC 210 -50 Required Outlets NEC 210 -52 Dwelling Unit Receptacle Outlets NEC 220 Branch - Circuit, Feeder and Service Calculations NEC 220 -3 Lighting load for Listed Occupancys Loads for Additions to Existing Installations NEC 380 -10 Switches NEC Table 10 Examples No 1(a) One Family Dwelling Oshkosh Chapter 11 -47 Oshkosh Chapter 11 -50 Oshkosh Mininum Housing Code 16 -34(3) If I can be of further help please call, 236 -5046. Sincerely, 7 rit4 4 - dalictArte--: John Sullivan Electrical Inspector MEMORANDUM DATE: April 3, 1995 TO: Oshkosh City Electrical Inspector FROM: Nancy Lovgren Per our telephone conversation, please send me copies of the electrical code pertaining to possible violations regarding the following circumstances: loose outlets dead outlets outlet boxes dead switches two -way switches (proper operation) disconnected fixtures (e.g. porch lights) proper circuitry (i.e. how many outlets can be on one breaker, procedure for labeling circuits, number of circuits for the kitchen) Please send this to my home address: 1917 Michigan Street Oshkosh, WI 54901 If you have questions, please call me at work, (414) 426 -4310, extension 4259, from 8:00 A.M. to 4:00 P.M. Thank you. h: \nancy \0587 WISCONSIN ADMINISTRATIVE CODE - REGISTER, MARCH 1994, NO. 459 WISCONSIN ADMINISTRATIVE CODE - REGISTER, MARCH 1994, NO. 459 INDUSTRY' LABOR AND HUMAN 4 (2) INSTALLATIONS OVER 600 VOLTS. Installations RELATIONS 44- over 600 volts shall, in addition to the requirements of ILHR 16.15 4 this chapter, comply with ch. PSC 114. (2) PETITION OF ADMINISTRATIVE RULE. Pursuant to History: Cr. Register, October 1990, No. 418, en. 11 -1 -90. s. 227.12, Slats., any municipality, corporation or any 5 ILHR 16.09 Inspection and maintenance. All electri- or more persons having an interest in an administrative cal installations and equipment shall be cleaned and rule may petition the department requesting the adop- inspected at intervals as experience has shown to be tion, amendment or repeal of the rule. necessary. Any equipment or electrical installation History: Cr. Register, October, 1990, No. 418, err. 11 -1-90. known to be defective so as to endanger life or property shall be promptly repaired, permanently disconnected, or Subchapter II - General Requirements isolated until repairs can be made. Construction, repairs, additions and changes to electrical equipment and con - ILHR 16.08 Construction and operation. (1) GENER- ductors shall be made by qualified persons only. AL. All electrical power and communication equipment History: Cr. Register, October 1990, No. ale, eft 11 -1 -90. and lines shall be constructed, installed, operated and maintained so as to minimize hazards to life and proper -, ILHR 16.10 Electrical Inspection of public buildings ty. All electrical installations shall conform to the National: s and places of employment. Inspection of electrical Electrical Code, incorporated by reference in this chap -. construction relating to public buildings and places of ter, and the requirements specified in this chapter. employment shall comply with the requirements of ch. Note: The federal and state Fair Housing Acts, the fade ILHR 17, subch. II. Americans with Disabilities Act and the Wisconsin Commercial History: Cr. Register, October 1990, No. 41e, erf.11 -1 -90. Building Code ( Chs. ILHR 50 to 64 ) contain requirements relating to making buildings accessible to and usable by people . ILHR 16.11 Use of approved materials and construc- with disabilities. Some of those requirements apply to the tion methods. (1) MATERIALS. Materials which do not installation of various electrical devices. For example, in the with the requirements of this chapter shall not be federal fair housing accessibility guidelines, devices such as comply 4 P light switches, electrical outlets, thermostats and other environ-, '`!,;` used unless approved by the department. The depart- mental controls would meet the requirements if operable part : ment shall approve materials, devices and systems of the controls are located no higher than 48 inches, and no t;.; which are listed by the following organizations, providing lower than 15 inches, above the floor. If the reach is over art ;' they do not conflict with the requirements of this chapter: obstruction between 20 and 25 inches in depth, the maximum height is reduced to 44 inches for forward approach; or 48 (a) Underwriters Laboratories, Inc.; inches for side approach, provided the obstruction is no more than 24 inches in depth. Complete copies of the federal Fait ; : , Housing Accessibility Guidelines or the federal Americans with. (b) Canadian Standards Association; Disabilities Act accessibility Guidelines can be obtained from ' the Superintendent of Documents, New Orders, P.O. Bo x = (c) ETL Testing Laboratories, Inc.; 371954. Pittsburgh, PA 15250 -7964. 12 13 DEPARTMENT OF INDUSTRY, LABOR AND HUMAN RELATIONS DEPARTMENT OF INDUSTRY, LABOR AND HUMAN RELATIONS S �� Article 110 — Requirements for Electrical Installations (b) Prevent Physical Damage. In locations where electric The Code requires that the rating of equipment be marked equipment would be exposed to physical damage, enclosures on the equipment and that such markings be located so as or guards shall be so arranged and of such strength as to pre- to be visible or easily accessible during or after installation. vent such damage. (c) Warning Signs. Entrances to rooms and other guarded 110-22. Identification of Disconnecting Means. Each discon- locations containing exposed live parts shall be marked with con- necting means required by this Code for motors and appliances, spicuous waming signs forbidding unqualified persons to enter. and each service, feeder, or branch circuit at the point where it originates, shall be legibly marked to indicate its purpose unless (FPN): For motors, see Sections 430 -132 and 430 - 133. For over located and arranged so the purpose is evident. The marking shall 600 volts, see Section 110 -34. be of sufficient durability to withstand the environment involved. Where circuit breakers or fuses are applied in compliance with Live parts of electric equipment should be covered, the series combination ratings marked on the equipment by the shielded, enclosed, or otherwise protected by covers, bar- manufacturer, the equipment enclosure(s) shall be legibly marked riers, mats, or platforms to prevent the likelihood of con- in the field to indicate the equipment has been applied with a tact by persons or objects. See definitions for "Dead Front," series combination rating. The marking shall be readily visible "Guarded," and "Isolated" in Article 100. and state "Caution — Series Rated System A Available. Iden- tified Replacement Component Required." 110-18. Arcing Parts. Parts of electric equipment which in ordi- nary operation produce arcs, sparks, flames, or molten metal shall (FPN): See Section 240 -83(c) for interrupting rating marking for end - be enclosed or separated and isolated from all combustible use equipment. material. Note that proper identification is to be specific. For exam - (FPN): For hazardous (classified) locations, see Articles 500 through ple, the marking is not merely to indicate "motor," but 517. For motors, see Section 430 -14. rather "motor, water pump "; not merely "lights," but rather "lights, front lobby." Consideration should also be given An example of electric equipment that produces sparks to the form of identification. Marking often fades or is cov- during "ordinary" operation is an open motor having ered by paint after installation. - commutators or collector rings. Adequate separation from The second paragraph requires series rated overcurrent combustible material is necessary where open motors devices to be legibly marked. The equipment manufac- are used. turer can mark the equipment that may be used with series combination ratings. If the installer installs equip - 110-18. Light and Power from Railway Conductors. Circuits ment in the field at its marked series combination rating, for lighting and power shall not be connected to any system con- the equipment must have an additional label as specified taining trolley wires with a ground retum. in this section to indicate that the series combination rat ing has been utilized. Exception: Car houses, power houses, or passenger and freight stations operated in connection with electric railways. B. Over 600 Volts, Nominal 110-21. Marking. The manufacturer's name, trademark, or other descriptive marking by which the organization responsible for the 110-80. General. Conductors and equipment used on circuits product may be identified shall be placed on all electric equip- over 600 volts, nominal, shall comply with all applicable provi- ment. Other markings shall be provided indicating voltage, cur- sions of the preceding sections of this article and with the fol- rent, wattage, or other ratings as are specified elsewhere in this lowing sections, which supplement or modify the preceding Code. The marking shall be of sufficient durability to withstand sections. In no case shall the provisions of this part apply to the environment involved. equipment on the supply side of the service conductors. 46 NATIONAL ELECTRICAL CODE HANDBOOK 1993 210-22 through 210 -50 Table 210 -24. Summary of Branch - Circuit Requirements CIRCUIT RATING 15 Amp 20 Amp 30 Amp 40 Amp 50 Amp CONDUCTORS: (Min. Size) Circuit Wires* Taps 14 12 10 8 6 Fixture Wires and Cords 14 14 14 12 12 Refer to Section 240 -4 OVERCURRENT PROTECTION 15 Amp 20 Amp 30 Am OUTLET DEVICES: Amp 40 Amp 50 Amp Lampholders I Permitted Any An y Heavy Heavy Du Receptacle T yp e Type Duty Duty Duty Rating ** 15 Max. 15 or 20 30 40 or 50 50 ry MAXIMUM LOAD Amp Amp Amp Amp Amp 15 Am PERMISSIBLE LOAD Amp 20 Amp 30 Amp 40 Amp 50 Amp i Refer to Refer to Refer to to o Refer to I Section Section Section Section Section 210 -23(a) 210 -23(a) b 210 -23 () 210 -23(c) 210-23(c) *These gauges are for co **For race copper conductors. receptacle rating of cord-connected electric - discharge lighting fixtures, see Section 410-30(c). 210 -24. Branch - Circuit Requirements — Summary. The the branch circuit to have a specific ampere rating that requirements for circuits having two or more outlets, other than is also the rating of the overcurrent device as stated in 10 the receptacle circuits of Section 220 -40) as specifically provided Section 210 - Thus, if the circuit breaker protecting the for above, are summarized in Table 210 -24. Branch circuits in branch circuit is rated 20 A, the conductors supplying this dwelling units shall supply only loads within that dwelling unit or circuit must have an ampacity of 20 amperes. Note that loads associated only with that dwelling unit. Branch circuits in accordance with the definition of ampacity, the required for the purpose of lighting, central alarm, signal, com- ampacity is determined after applying all derating factors, munications, or other needs for public or common areas shall such as those in Note 8(a) of Notes to Ampacity Tables i" ►, not be supplied from a dwelling unit panelboard. of 0 to 2,000 Volts. Where 7 to 9 such conductors are The second sentence of Section 210 -24 is intended to pre- in one conduit, a No. 12 THHN copper conductor vent overloading of branch circuits. The last sentence (30 A per Table 310 -16) derated to 70 percent per Note requires the house loads for common areas and common 8(a) would have an ampacity of 21 A and would be suit - systems to be supplied from a panelboard that is not located able for a load of 20 A. It would thus be acceptable for in any of the dwelling units. This is intended to permit access use on the 20 -A multioutlet branch circuit. to the branch - circuit disconnecting means without the need to enter the space of any tenants. It also is intended to pre- vent a tenant from turning off important circuits that may C. Required Outlets affect other tenants. Table 210 -24 summarizes branch- circuit requirements 210-50. of conductors, overcurrent protection, outlet devices, max ified in Section 210-52 1 rrough 210 -63x11 be installed as spec imum load, and permissible loads where two or more out- lets are supplied. Where the branch circuit serves a fixture load and sup a (a) Cord Pendants. A cord connector that is supported by plies two or more fixture outlets, Section 210 - requires tacl a outlet installed COQ pendant shall be considered a recep i 1993 NATIONAL ELECTRICAL CODE HANDBOOK 75 Article 210 — Branch Circuits (b) Cord Connections. A receptacle outlet shall be installed A "wallspace" is a wall unbroken along the floor line by wherever flexible cords with attachment plugs are used. Where doorways, fireplaces, archways, and similar openings and flexible cords are permitted to be permanently connected, it shall may include two or more walls of a room (around corners, be permitted to omit receptacles for such cords. as illustrated in Figure 210 - 26). Flexible cords are permitted to be permanently connected Fixed room dividers, such as bar -type counters and rail to boxes or fittings where specifically permitted by the Code. ings, are to be included in the 6 -foot measurement. Fixed However, plugging a cord into a lampholder by inserting a panels in exterior walls are counted as regular wall space, screw -plug adapter is not permissible. See Section 410 -47. and a floor -type receptacle close to the wall can be used to meet the required spacing. Isolated, individual wall spaces (c) Appliance Outlets. Appliance receptacle outlets installed 2 feet or more in width are considered usable for the loca- in a dwelling unit for specific appliances, such as laundry equip- tion of a lamp or appliance, and a receptacle outlet is ment, shall be installed within 6 feet (1.83 m) of the intended loca- required to be provided. tion of the appliance. • See Sections 210 -52(f) and (g) and 220 -4(c). 2 ft 210-52. Dwelling Unit Receptacle Outlets. f H (a) General Provisions. In every kitchen, family room, din- 6 ft 6 ft ing room, living room, parlor, library, den, sun room, bedroom, • recreation room, or similar room or area of dwelling units, recep- F loor receptacle • • tale outlets shall be installed so that no point along the floor line F ixed panel T in any wall space is more than 6 feet (1.83 m), measured hor- izontally, from an outlet in that space, including any wall space 2 feet (610 mm) or more in width and the wall space occupied by fixed panels in exterior walls, but excluding sliding panels in 12 ft 12 ft exterior walls. The wall space afforded by fixed room dividers, such as freestanding bar-type counters or railings, shall be • included in the 6 -foot (1.83 -m) measurement. As used in this section, a "wall space" shall be considered a wall unbroken along the floor line by doorways, fireplaces, and similar openings. Each wall space 2 feet or more (610 mm or • more) wide shall be treated individually and separately from other wall spaces within the room. A wall space shall be permitted to 6 ft include two or more walls of a room (around comers) where unbroken at the floor line. 411 (FPN): The purpose of this requirement is to minimize the use of 12 ft 0 j 4 6 ft-i.1 cords across doorways, fireplaces, and similar openings. Figure 210 -26. Plan view of the location of receptacles in a Receptacles are required to be located so that no "point" typical room. in any wall space is more than 6 feet from a receptacle. This rule intends that an appliance or lamp with a flexible cord Receptacle outlets shall, insofar as practicable, be spaced attached may be placed anywhere in the room and be within equal distances apart. Receptacle outlets in floors shall not be 6 feet of a receptacle, thus eliminating the need for exten- counted as part of the required number of receptacle outlets sion cords. unless located close to the wall. 76 NATIONAL ELECTRICAL CODE HANDBOOK 1993 210 -50 through 210 -52 The receptacle outlets required by this section shall be in addi- tion to any receptacle that is part of any lighting fixture or appli ance, located within cabinets or cupboards, or located over -'�f-IPISI 5/2 feet (1.68 m) above the floor. I CI Exception: Permanently installed electric baseboard heaters equipped with factory- installed receptacle outlets or outlets pro- Convector slots e vided as a separate assembly by the manufacturer shall be per- 12 ft '� z mitted as the required outlet or outlets for the wall space utilized I s by such permanently installed heaters. Such receptacle outlets Lamp cord shall not be connected to the heater circuits. Figure 210 - 28. Many electrical baseboard heaters are of the low - density type and are designed to be longer than 12 feet. To meet (FPN): Listed baseboard heaters include instructions that may riot the spacing requirements of Section 210- 52(a), it is necessary that permit their installation below receptacle outlets. the required receptacle be located as a part of the heater unit. According to listing instructions [see Section 110- 3(b)], per- pantry, breakfast room, dining room, or similar area of a dwell- ti manent electric baseboard heaters are not permitted to be ing unit. Such circuits, whether two or more are used, shall ! located beneath wall receptacles. Where the receptacle is a part have no other outlets. of the heater, cords of appliances or lamps are less apt to be exposed to the heating elements, as might occur should they Exception No. 1: A receptacle installed solely for the electrical fall into convector slots. See Figures 210 - and 210 - 28. supply to and support of an electric clock in any of the rooms specified above. I SO Exception No. 2: Outdoor receptacles. . - - ti Exception No. 3: In addition to the required receptacles spec- ified by Section 210 -52, switched receptacles supplied from a general- purpose branch circuit as defined in Section 210- 70(a), (ii Exception No. 1 shall be permitted. Exception No. 4: A receptacle served by a circuit supplying only tl ' _1 motor loads. (i l) Exception No. 5: Receptacles installed to provide power for elec- ~ tric ignition systems or clock timers for gas -fired ranges, ovens, or counter- mounted cooking units. i . l' This exception is intended to allow the small electrical loads associated with gas -fired appliances to be connected Figure 210 -27. An electric baseboard heater with a receptacle to small appliance branch circuits. I outlet provided as the required receptacle outlet for the wall space. (2) Receptacles installed in the kitchen to serve counter (Square D Co.) top surfaces shall be supplied by not less than two small appli- ance branch circuits, either or both of which shall also be per - (b) Small Appliances. mitted to supply receptacle outlets in the kitchen and other rooms specified in Section 210- 52(b)(1). Additional small appli- (1) The two or more 20- ampere small appliance branch ance branch circuits shall be permitted to supply receptacle circuits required by Section 220 -4(b) shall serve all recepta- outlets in the kitchen and other rooms specified in Section cle outlets, including refrigeration equipment, in the kitchen, 210 -52(b) (1). 1993 NATIONAL ELECTRICAL CODE HANDBOOK 77 Article 210 — Branch Circuits Section 210 -52(b) requires two or more 20 -A circuits for There is no restriction placed on the number of outlets all receptacle outlets for the small appliance loads, includ- connected to a general lighting or small- appliance branch ing refrigeration equipment [see FPN following Section 210- circuit. The minimum number of receptacle outlets in a 8(a)(5)], in the kitchen, dining room, pantry, and breakfast room is determined by Section 210- 52(a). It is desirable to room of a dwelling unit. Counter top receptacle outlets in provide more than the minimum number of receptacle out - kitchens are required to be supplied by no fewer than two lets required, thereby further reducing the need for use of small- appliance branch circuits. These circuits may also sup- extension cords. Section 210- 52(b)(1), Exception No. 3 per - ply receptacle outlets in the pantry, dining room, and break- mits switched receptacles supplied from general purpose fast room as well as an electric clock receptacle, electric loads branch circuits to be located in these areas. associated with • as fired appliances, or outdoor receptacles, (c) Counter Tops. In kitchens and dining areas of dwelling but are to have no other outlets. See Sections 210 8(a)(3) units, a receptacle outlet shall be installed at each wall counter and (a)(5) for GFCI requirements. space 12 inches (305 mm) or wider. Receptacle outlets shall be At least one additional 20 - branch circuit is required to installed so that no point along the wall line is more than 24 be provided for the supply to the laundry receptacle outlet(s). inches (610 mm), measured horizontally from a receptacle out- This circuit is to have no other outlets. See Figure 210 -29. let in that space. Counter top receptacles in kitchens and dining areas Outdoor Clock receptacle receptacle GFCI are now required to be located so that no point along the 4 t wall line is more than 24 inches from a receptacle. Island and peninsular counter tops 12 inches and wider are l r ,j � Sink O GFCI' required to have at least one receptacle for each 4 feet GFCI Pantry of counter space. Kitchen Receptacles rendered inaccessible by appliances fastened tip S____ GFCI =� Gas in place or installed for appliances occupying dedicated 4 1 Oven - . igniter space, such as dishwashers, garbage disposal units, built -in x gas ovens, waste compactors, etc., are not considered as the 0 0 0 I required receptacles. 0 III Dining S 0 0 -- room ' 4 A receptacle outlet shall be installed at each island or penin- ' sular counter top with a long dimension of 24 inches (610 mm) Refrigerator or greater and a short dimension of 12 inches (305 mm) or III II greater. Receptacle outlets to serve island or peninsular counter II ' Gen. purpose tops shall be installed above, or within 12 inches (305 mm) below R the counter top. Receptacle outlets shall be installed so that no 20A Small appliance point along the centerline of the long dimension is more than 24 circuits inches (610 mm), measured horizontally from a receptacle out- let in that space. A peninsular counter top is measured from the Figure 210 -29. This figure illustrates the application of require - connecting edge. ments of Section 210- 52(b)(1) and (2). Though these small - appliance branch circuits may serve certain outlets in other specified Counter top spaces separated by range tops, refrigerators, or areas, they are not permitted to serve any other outlets such as sinks shall be considered as separate counter top spaces. Recep- might be connected to exhaust hoods or fans, disposals or dish - tacle outlets rendered not readily accessible by appliances fas- washers. The counter top receptacles are required to be supplied tened in place or appliances occupying dedicated space shall by two circuits (see Section 210- 52(b)(2)J; receptacles in other not be considered as these required outlets. rooms are not. Receptacles within 6 feet of the kitchen sink installed to serve counter top surfaces are required to be GFCI Receptacle outlets shall not be installed in a face -up position protected in accordance with Section 210 8(a)(5). in the work surfaces or counter tops in a kitchen or dining area. 78 NATIONAL ELECTRICAL CODE HANDBOOK 1993 ■ ■ Section 210 -52 141-2, I 2, 6 „ -10i 1.4-2,-1.1.0--4,— (d) Bathrooms. In dwelling units, at least one wall recepta- cle outlet shall be installed in the bathroom adjacent to each basin db db i location. See Section 210- 8(a)(1). Refrigerator GFCI GFCI GFCI • A In bathrooms of a dwelling unit, one wall receptacle is DW required to be installed adjacent to the wash basin and is 2' A _ required in addition to any receptacle that may be part of any lighting fixture or medicine cabinet. Where there is more � euxc Sink than one basin, a receptacle outlet is required adjacent to Isx.c each basin location. Where the basins are in close proxim- us ity, one receptacle outlet installed between the two basins COOK 4' G FC 1®= -- may satisfy this requirement. All 125 -V single -phase, 15- m 2 , and 20 -A receptacles installed in bathroom areas are BRI 1 .0-2' " � ,� required to have ground -fault circuit- interrupter protection (� 1411-12"-01 O O for personnel including the optional receptacle that may be SE i part of a lighting fixture. See Figure 210 -9. bt 0 0 (e) Outdoor Outlets. For a one-family dwelling and each unit 4' of a two-family dwelling that is at grade level, at least one recep- I 2' tacle outlet accessible at grade level shall be installed at the front and back of the dwelling. See Section 210- 8(a)(3). The rule for one- and two - family dwellings requires two r eceptacle outlets for each dwelling unit, as shown in Fig- t 4 ' ure 210 -31. 1.4-2'—•±11--4' 10.1.4 4' • IAA I Installation of outdoor receptacles requires that care be taken to ensure that the receptacle faceplate rests securely Figure 210 -30. Section 210 -52(c) requires a receptacle outlet at on the supporting surface to prevent moisture from enter - each counter space wider than 12 inches spaced so that no point ing the enclosure. Where uneven surfaces such as brick, along the wall line is more than 24 inches from a receptacle. Pen- stone, or stucco are encountered, it may be necessary to close k' insular type counter tops are required to have one receptacle for openings with caulking compound or mastic. See also Sec - each 4 feet of counter top. The measurement of a peninsular type tion 410 -57. counter top is from the edge connecting to the nonpeninsular counter. A receptacle outlet is required at each island-type counter top with a short dimension of at least 12 inches and a long dimen- Fence lion of at least 24 inches. A receptacle outlet is required for each r T T -1 I I 4 feet of island counter top space, so located that no point along I I the center line of the long dimension is more than 24 inches mea- GFCI 1 GFCI 1 GFCI sured horizontally from the receptacle outlet. 1 qp 1 Receptacles installed in a face -up position in a counter One family One family One family top could collect crumbs, liquids, and other debris, result- dwelling dwelling dwelling ing in a potential fire or shock hazard. ....—F ire walls — (FPN): The 24 -inch (610 -mm) dimension is measured along the L. clb 1.1 db 1.1 db wall line or centerline, and the intent is that there be a recepta- GFCI GFCI cle outlet for every 4 linear feet (1.2 m) or fraction thereof of Figure 210 -31. An example of "row” housing. A receptacle is counter length. required at the front and rear of each one - family dwelling. 1993 NATIONAL ELECTRICAL CODE HANDBOOK 79 Article 220 - Branch - Circuit, Feeder, and Service Calculations C. Optional Calculations for Computing Feeder and ARTICLE 220 Branch - Circuit, Feeder, and Service Loads Service Calculations 220-30. Optional Calculation - Dwelling Unit. (a) Feeder and Service Load. Contents (b) Loads. A. General 220 -31. Optional Calculation for Additional Loads in Existing Dwelling Unit. 220 -1. Scope. 220 -32. Optional Calculation - Multifamily Dwelling. 220 -2. Voltages. (a) Feeder or Service Load. 220 -3. Computation of Branch Circuits. (b) House Loads. (a) Continuous and Noncontinuous Loads. (c) Connected Loads. (b) Lighting Load for Listed Occupancies. 220 -33. Optional Calculation - Two Dwelling Units. (c) Other Loads - All Occupancies. 220 -34. Optional Method - Schools. (d) Loads for Additions to Existing Installations. 220 -35. Optional Calculations for Additional Loads to Existing Installations. 220-4. Branch Circuits Required. 220 -36. Optional Calculation - New Restaurants. (a) Number of Branch Circuits. (b) Small Appliance Branch Circuits - Dwelling D. Method for Computing Farm Loads Unit. 220 -40. Farm Loads - Buildings and Other Loads. (c) Laundry Branch Circuits - Dwelling Unit. (a) Dwelling Unit. (d) Load Evenly Proportioned Among Branch Circuits. (b) Other than Dwelling Unit. 220 -41. Farm Loads - Total. B. Feeders 220 -10. General. A. General (a) Ampacity and Computed Loads. 220-1. Scope. This article provides requirements for determin- (b) Continuous and Noncontinuous Loads. , ing the number of branch circuits required and for computing I 220-11. General Lighting. branch - circuit, feeder, and service Toads. 220 -12. Show- Window Lighting. 220 - 13. Receptacle Loads - Nondwelling Units. The scope of Article 220 is clarified in the 1993 Code to verify that it includes services. See Section 230- 42(a). 220 -14. Motors. 220 -15. Fixed Electric Space Heating. Exception: Branch circuit and feeder calculations for electrolytic 220 -16. Small Appliance and Laundry Loads - Dwelling cells as covered in Section 668 -3(c), Exception Nos. 1 and 4. Unit. A similar exception also appears after Sections 210 - 1, (a) Small Appliance Circuit Load. 215 -1, and 225 -1. (b) Laundry Circuit Load. 220 -17. Appliance Load - Dwelling Unit(s). 220-2. Voltages. Unless other voltages are specified, for pur- 220-18. Electric Clothes Dryers - Dwelling Unit(s). poses of computing branch - circuit and feeder loads, nominal sys- 220-19. Electric Ranges and Other Cooking Appliances - tem voltages of 120, 120/240, 208Y/120, 240, 480Y/277, 480, Dwelling Unit(s). and 600 volts shall be used. 220 - 20. Kitchen Equipment - Other than Dwelling For uniform application of the provisions of Articles 210, Unit(s). 215, and 220, nominal voltages as listed in Section 220 -2 220 -21. Noncoincident Loads. are required to be used in computing the ampere load on 220 -22. Feeder Neutral Load. the conductors. 86 NATIONAL ELECTRICAL CODE HANDBOOK 1993 Article 215 – Contents through 220 -3 See Chapter 9, Examples 1 through 5(b). The results of computed loads or the continuous portions of combined these examples are generally expressed in amperes. Except continuous and noncontinuous computed loads are to be where the computations result in a major fraction of an calculated at 125 percent. See Section 220 -3(a). ampere (0.5 or larger), such fractions may be dropped. The rating of the overcurrent device must not exceed the To select conductor sizes, refer to Section 310 -15 and, final ampacity of the conductors after any applicable der - where applicable, the Notes to Ampacity Tables of 0 to ating factors (such as a high ambient location) have been 2,000 Volts. calculated. See Section 240 -3 (a) through (m) for informa- d Loads are computed on the basis of volt - amperes (VA) tion permitting exceptions to this basic rule. Bg or kVA rather than watts or kW. However, the rating of The rating of the overcurrent device is then used to rate MI equipment is given in watts or kW. Such ratings are con- the branch circuit. For example, it may be a 15 -, 20 -, 30 -, NOM MCI sidered the equivalent of the same rating in volt - amperes 40 -, or 50 -amp branch circuit. See Section 210 -3. or kVA. See, for example, Section 220 -19. This recognizes (b) Lighting Load for Liste Occupancies. A unit Toad of m that load calculations are to determine conductor and cir not less than that specified in Table 220 - 3(b) for occupancies cuit sizes, that the power factor of the load is often a listed therein shall constitute the minimum lighting load for each W si unknown, and that the conductor "sees" the circuit volt square foot (0.093 sq m) of floor area. The floor area for each H amperes only, not the circuit power (watts). floor shall be computed from the outside dimensions of the build- ing, apartment, or other area involved. For dwelling unit(s), the 2204. Computation of Branch Circuits. Branch - circuit loads computed floor area shall not include open porches, garages, shall be computed as shown in (a) through (d) below. or unused or unfinished spaces not adaptable for future use. (FPN): See Section 600 -6(c) for exterior signs and outline lighting. Examples of "unused or unfinished" spaces are some (a) Continuous and Noncontinuous Loads. The branch - attics and some crawl spaces. '1 circuit rating shall not be less than the noncontinuous load plus (FPN): The unit values herein are based on minimum Toad con - 125 percent of the continuous Toad. ditions and 100 percent power factor, and may not provide sufficient a See Figure 220 - capacity for the installation contemplated. i 6 (c) Other Loads — All Occupancies. In all occupancies, the 1 Ibi No. 12 AWG minimum Toad for each outlet for general -use receptacles and k t conductors . - 20 A ( 4A — 4A — 4A — 4A -4—Branch outlets not used for general illumination shall be not less than — — — circuit the following, the loads shown being based on nominal branch - 20 4—, Total continuous circuit voltages. load =16 amperes (1) Outlet for a specific appliance or other load except for "-20 A 16 x 125% = 20 Amps a motor Toad ....ampere rating of appliance or Toad served. OC device (2) Outlet for motor load. See Sections 430-22 and 430-24 and Article 440. (3) An outlet supplying recessed lighting fixture(s) shall be Figure 2204. Continuous loads, such as store lighting, must be the maximum volt- ampere rating of the equipment and lamps calculated at 125 percent to determine the ampacity of the con- for which the fixture(s) is rated. ductor and the branch circuit size. Recessed lighting is included in the 3 volt amperes per Exception: Where the assembly, including overcurrent devices, square foot for dwellings where used for general lighting. is listed for continuous operation of 100 percent of its rating. (4) Outlet for heavy -duty lampholder ....600 volt- amperes. The computed load is used to determine the ampacity (5) Track Lighting. See Section 410 - 102. required for the branch- circuit conductors. Continuous (6) Other outlets* 180 volt- amperes per outlet. 1993 NATIONAL ELECTRICAL CODE HANDBOOK 87 Article 220 — Branch- Circuit, Feeder, and Service Calculations For receptacle outlets, each single or each multiple receptacle in guest rooms of hotels and motels is included in Table i on one strap shall be considered at not less than 180 volt - amperes. 220 - (b). (See asterisk note to table.) The load requirement 1 *This provision shall not be applicable to receptacle outlets con- for the small appliance branch circuits is 1,500 VA per cir netted to the circuit specified in Section 220 -4(b). cuit. See Section 220 16(a). I 1 I Table 220-34). General Lighting Loads By Occupancies ® Io 00 Unl Load per O ® ® 0 0 Square Foot of Occupancy (Volt Amperes) outlet VA 180 VA 180 VA outl VA Type pa y outlet outlet outlet outlet Armories and Auditoriums 1 Banks 3 '/2 ** Barber Shops and Beauty Parlors 3 Churches 1 Clubs 2 Figure 220 - 2. The 180 - VA rating is applied to single and Court Rooms 2 Dwelling Units* 3 multiple- receptacle outlets on a single strap. Note that the last Garages — Commercial (storage) '1 outlet consists of two duplex outlets on separate straps. There - Hospitals 2 fore, it would be calculated at 360 VA. Hotels and Motels, including apartment houses without provision for cooking by tenants* 2 A load of 180 volt- amperes is not required to be con - Industrial Commercial (Loft) Buildings 2 Lodge Rooms 1 sidered for outlets supplying recessed lighting fixtures, out- Office Buildings 31 ** lets for general illumination, and small - appliance branch Restaurants 2 Schools 3 circuits. To apply the 180 -VA requirement in this case Stores 3 would be unrealistic, as it would unnecessarily restrict the Warehouses (storage) 1/4 n umber of lighting or receptacle outlets on a branch cir In any of the above occupancies except one- g g p family dwellings and individual dwelling cuit. See the single asterisk note below Table 220 -3(b) and units of two- family and multifamily the asterisk note below Section 220- 3(c)(5). These indi- dwellings: Assembly Halls and Auditoriums 1 cate the 180 -VA requirement is not applicable to most Halls, Corridors, Closets, Stairways 1 /2 receptacle outlets in dwellings. Storage Spaces 1 /4 For SI units: one square foot = 0.093 square meter. 10 Outlets on a 15 A receptacle circuit *M general - use receptacle oWets of 20- ampere or less rating in one - family, two- family, and multifamily dwellings and in guest rooms of hotels and motels (except those connected to the receptacle circuits specified in Sections 220-4(b) and (c)i shall be considered as outlets for general illumination, and no additional load cal- culations shell be required for such outlets. __ 0 0 o o o o 0 0 0 In addition, a unit bad of 1 volt-ampere per square foot shall be included for — — — — — general- purpose receptacle outlets where the actual number of general-purpose receptacle outlets is unknown. O O O O ® O O O 0 0 0 0 0 0 0 0 0 O 0 0 0 0 The 180 -VA load is applied to single and multiple recep- 0 og tacles mounted on a single yoke or strap and is considered o as "other outlets" in accordance with Section 220- 3(c)(6). Y The "other outlets" mentioned above are not the outlets 13 Outlets on a 20 A receptacle circuit installed for general illumination or the small appliance Figure 220 Computation of the maximum number of outlets branch circuits. permitted on 15- and 20-A branch circuits. This is not applica- The receptacle load for outlets for general illumination ble to outlets connected to a general lighting or small appliance in one- and two- family and multifamily dwellings and branch circuit. 88 NATIONAL ELECTRICAL CODE HANDBOOK 1993 220 -3 through 220-4 Exception No. 1: Where fixed multioutlet assemblies are employed, each 5 feet (1.52 m) or fraction thereof of each sep- &i i 3 W j arate and continuous length shall be considered as one outlet yd of not less than 180 volt - amperes capacity; except in locations niifisO where a number of appliances are likely to be used simulta- I neously, each 1 foot (305 mm) or fraction thereof shall be con- g g o � a a I - - ` sidered as an outlet of not less than 180 volt- amperes. The requirements of this exception shall not apply to dwelling unit(s) 1' 10 ft a d or the guest rooms of hotels or motels. 200 volt per linear foot 200 VA x 10 ft = 2000 volt- amperes HOU Figure 220-5. For branch- circuit loads, the linear foot calculation f' 5 ft ►1 method is permitted in lieu of the specified unit load per outlet. s ® ® IRO Z , Considered as one outlet Exception No. 4: The loads of outlets serving switchboards and y rated 180 VA switching frames in telephone exchanges shall be waived from the computations. Fa 5 ft ► I Exception No. 5: Section 220-18 shall be considered as a per- 8 IRO ® ® ® ® mitted method of computing the load for a household electric I clothes dryer. I Outlets likely to be used (d) Loads for Additions to Existing Installations. SI� simultaneously - each foot rated 180 VA (1) Dwelling Units. Loads for structural additions to an (5 ft x 180 VA =900 VA) existing dwelling unit or to a previously unwired portion of an existing dwelling unit, either of which exceeds 500 square feet Figure 220-4. Fixed multioutlet assemblies are commonly used (46 5 sq m), shall be computed in accordance with (b) above. in commercial or industrial locations and may have been selected for a number of receptacles along a given work area (light use) Loads for new circuits or extended circuits in previously wired or for the simultaneous connection and use of a number of appli dwelling units shall be computed in accordance with either i tk it t ances (heavy use). (b) or (c) above. (2) Other than Dwelling Units. Loads for new circuits or Exception No. 2: Table 220-19 shall be permitted for comput- extended circuits in other than dwelling units shall be com- ing the load of household electric ranges. puted in accordance with either (b) or (c) above. Exception No. 3: A load of not less than 200 volt - amperes per 2204. Branch Circuits Required. Branch circuits for lighting linear foot (305 mm) of show window, measured horizontally and for appliances, including motor - operated appliances, shall along its base, shall be permitted instead of the specified unit be provided to supply the Toads computed in accordance with load per outlet Section 220 -3. In addition, branch circuits shall be provided for There are two options permitted for the load calculations specific loads not covered by Section 220-3 where required else - where in this Code; for small appliance Toads as specified in (b) for branch circuits serving show windows. Option No. 1: 180 VA per receptacle (Note Section below; and for laundry loads as specified in (c) below. 210 - requires 1 receptacle per 12 linear feet.) (a) Number of Branch Circuits. The minimum number of Option No. 2: 200 VA per linear feet per Exception No. branch circuits shall be determined from the total computed load 3 to Section 220 - 3(c) above. and the size or rating of the circuits used. In all installations, the See Figure 220 - number of circuits shall be sufficient to supply the load served. 1993 NATIONAL ELECTRICAL CODE HANDBOOK 89 Article 220 — Branch - Circuit, Feeder, and Service Calculations In no case shall the load on any circuit exceed the maximum (d) Load Evenly Proportioned Among Branch Circuits. specified by Section 210 -22. Where the load is computed on a volt- amperes- per - square -foot (b) Small Appliance Branch Circuits — Dwelling Unit. In (0.093 -sq m) basis, the wiring system up to and including the addition to the number of branch circuits determined in actor- branch - circuit panelboard(s) shall be provided to serve not less dance with (a) above, two or more 20- ampere small appliance than the calculated load. This load shall be evenly proportioned branch circuits shall be provided for all receptacle outlets spec- among muttioutlet branch circuits within the panelboard(s). ified by Section 210 -52 for the small appliance loads. Branch - circuit overcurrent devices and circuits need only be installed to serve the connected load. See Section 210 -52(c) for requirements for the spacing of counter top receptacle outlets. (FPN): See Examples 1(a), 1(b), 2(b), and 4(a), Chapter 9. (c) Laundry Branch Circuits — Dwelling Unit. In addition to There is no restriction placed on the number of outlets the number of branch circuits determined in accordance with (a) connected to a general lighting or small- appliance branch - and (b) above, at least one additional 20 ampere branch circuit shall circuit. The number of general receptacle outlets in a room be provided to supply the laundry receptacle outlet(s) required by is determined by Section 210- 52(a). See Section 210 -52(c) Section 210- 52(f). This circuit shall have no other outlets. for number of receptacle outlets at counter tops. It is desir- At least one additional 20 -A branch circuit is required able to provide more than the minimum number of recep- to be provided for the supply to the laundry receptacle out- tacle outlets required, thereby further reducing the need for let(s) required by Section 210- 52(f). This circuit is to have use of extension cords. no other outlets. Laundry receptacle outlets are not required Consideration must be given to balancing the loads when in apartments or similar occupancies where there are com- terminating circuits in panelboards. mon laundry facilities available to all occupants. In addi- tion, a laundry outlet is not required if laundry facilities are B. Feeders not to be installed or permitted. See Figure 220 -6. 220-10. General. (a) Ampacity and Computed Loads. Feeder conductors shall have sufficient ampacity to supply the load served. In no GFCI case shall the computed load of a feeder be less than the sum NI See Section 210 -52(g) and of the loads on the branch circuits supplied as determined by Part Section 210- 81a1(4) A of this article after any applicable demand factors permitted GFCI GFCI by Parts B, C, or D have been applied. Optional receptacle _ See Figure 220 -7. Furnace (FPN): See Examples 1 through 10, Chapter 9. See Section n en 210 -22(b) for maximum load in amperes permitted for lighting units basement Unfinished Laundry area operating at Tess than 100 percent power factor. 1 —\ Washer Dryer (b) Continuous and Noncontinuous Loads. Where a ou A dryer Water heater O feeder supplies n continuous loads or any combination of contin- outlet u ous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus 125 20 A laundry circuit percent of the continuous load. Figure 220-6. At least one 20-A branch circuit is required to sup- This section was revised for the 1990 Code. It requires ply the laundry receptacle outlet(s). Lighting outlets in laundry areas are not permitted to be connected to the laundry branch circuit. the overcurrent device for a feeder to be sized at not less If the laundry area is in a basement or garage, this receptacle out - than the sum of the combination of the noncontinuous loads let is not considered as that required by Section 210- 52(g). plus 125 percent of the continuous loads. 90 NATIONAL ELECTRICAL CODE HANDBOOK 1993 220-4 through 220 -13 Table 220 -11. Lighting Load Feeder Demand Factors Portion of Lighting Load Demand \ to which Demand Factor J 250 Amp Type of Occupancy Factor Applies (volt - amperes) Percent Feeder conductors -0- -250 kcmil, THWN Dwelling Units First 3000 or less at 100 From 3001 to 120,000 at 35 Remainder over 120,000 at 25 O O O -4 Meters Remainder First 5r at 40 Remainder nder ovyer r 50 50,000 at 20 1??I Hotels and Motels . lol THWN —•—■ — Including Apartment z 0 100A -- 100A — 100A Houses without e Panel Panel Panel Provision for First 20,000 or less at 50 Cooking by From 20,001 to 100,000 at 40 t Tenants* Remainder over 100,000 at 30 I Figure 220 -7. Each panel serves a computed load of 80 amps. Warehouses First 12,500 or less at 100 bt The main feeder is sized to carry Wareho rry a minimum ,of 240 amps Wareho Remainder over less ss at at 50 (3 x 80). The feeders from the meter enclosure to the panelboards 100 are sized to provide a minimum of 80 amps. It is not intended that All Others Total volt amperes the main feeder be sized to carry 300 amps. See Figure 230 -16 *The demand factors of this table shall not apply to the computed load of feed - for a similar example for service conductors. ers to areas in hospitals, hotels, and motels where the entire lighting is likely to i be used at one time, as in operating rooms, ballrooms, or dining rooms. The ungrounded service conductors are no longer required y to be sized at this value. Service conductors are required to 40 have sufficient ampacity to carry the loads computed in See Figure 220 -6 for an example of a 20 -A laundry accordance with Article 220, with appropriate demand fac- branch circuit. tors applied. See Sections 230 -23, 230 -31, and 230 -42. 220 -12. Show - Window Lighting. For show - window lighting, a load of not less than 200 volt-amperes shall be included for Exception: Where the assembly including the overcurrent devices protecting the feeder(s) are listed for operation at 100 percent each linear foot (305 mm) of show window, measure horizon- , of their rating, neither the ampere rating of the overcurrent device tally along its base. nor the ampacity of the feeder conductors shall be less than the The 200 - calculation for each linear foot of a show sum of the continuous load plus the noncontinuous load. window is required to calculate the FEEDER load. See com- Sections 220 -10 through 220 -22, which are included in mentary following Section 220- 3(c)(6) Exception No. 3 for Part B, contain the requirements for calculating feeder and load calculations for branch circuits. service loads. Sections 220 -30 and 220 -32 contain optional methods for calculating feeder and service loads in dwell- (FPN): See Section 220 -3(c), Exception No. 3, for branch circuits supplying show windows. ing units and multifamily dwellings. 221 General Lighting. The demand factors listed in Table 220-13. Receptacle Loads — Nondwelling Units. In other 220-11 shall apply to that portion of the total b ranch ircuit load coat- than dwelling units, receptacle loads computed at not more than Puted for general illumination. They shall not be applied in deter- 180 volt- amperes per outlet in accordance with Section mining the number of branch circuits for general illumination. 220- 3(c)(6) shall be permitted to be added to the lighting loads and made subject to the demand factors given in Table 220 -11, (FPN): See Section 220 -16 for application of demand factors to or they shall be permitted to be made subject to the demand fac- small appliance and laundry loads in dwellings. tors given in Table 220 -13. 1993 NATIONAL ELECTRICAL CODE HANDBOOK 91 Article 380 – Contents through 380 -9 380-5. Time Switches, Flashers, and Similar Devices. Time Exception: Double -throw switches. switches, flashers, and similar devices shall be of the enclosed Oi type or shall be mounted in cabinets or boxes or equipment °°"� enclosures. Energized parts shall be barriered to prevent oper Accessibility and Grouping. casi ator exposure when making manual adjustments or switching. (a) Location. All switches and circuit breakers used as no Exception: Where mounted so they are accessible only to qua/ switches shall be so located that they may be operated from F a persons and so located in an enclosure that any energized a readily accessible place. They shall be so installed that the center of the grip of the operating handle of the switch or cir- parts within 6 inches (152 mm) of the manual adjustment or cult breaker, when in its highest position, will not be more than switch are covered by suitable barriers. 6 feet (1.98 m) above the floor or working platform. 380 8. Position of Knife Switches. Exception No. 1: On busway installations, fused switches and circuit breakers shall be permitted to be located at the same level (a) Single -Throw Knife Switches. Single -throw knife as the busway. Suitable means shall be provided to operate the switches shall be so placed that gravity will not tend to close them. handle of the device from the floor. Single -throw knife switches, approved for use in the inverted posi- tion, shall be provided with a locking device that will ensure that Exception No. 2: Switches installed adjacent to motors, appli- the blades remain in the open position when so set. ances, or other equipment that they supply shall be permitted (b) Double -Throw Knife Switches. Double throw knife to be located higher than specified in the foregoing and to be switches shall be permitted to be mounted so that the throw will accessible by portable means. be either vertical or horizontal. Where the throw is vertical, a lock- Exception No. 3: Hookstick operable isolating switches shall be ing device shall be provided to hold the blades in the open posi- permitted at greater heights. tion when so set. (c) Connection of Knife Switches. Single -throw knife (b) Voltage Between Adjacent Switches. Snap switches shall switches shall be so connected that the blades are deenergized not be grouped or ganged in enclosures unless they can be so when the switch is in the open position. arranged that the voltage between adjacent switches does not exceed 300, or unless they are installed in enclosures equipped Exception: Where the load side of the switch is connected to cir- with permanently installed barriers between adjacent switches. cults or equipment, the inherent nature of which may provide a ;, 1 backfeed source of power. For such installations, a permanent sign shall be installed on the switch enclosure or immediately �-9 . Faceplates for Flush- Mounted Snap Switches. Flush adjacent to open switches that reads: "WARNING —LOAD SIDE snap switches, that are mounted in ungrounded metal boxes and located within reach of conducting floors or other conducting sur- OF SWITCH MAYBE ENERGIZED BY BACKFEED. " faces, shall be provided with faceplates of nonconducting, non - Typical backfeed sources are batteries, generators, and combustible material. Metal faceplates shall be of ferrous metal double -ended switchboard ties. These may cause the switch not less than 0.030 inch (0.762 mm) in thickness or of nonferrous blades to be energized when the switch is in the open post- metal not Tess than 0.040 inch (1.016 mm) in thickness. Face - tion, a condition inherent to the circuitry, plates of insulating material shall be noncombustible and not less than 0.10 inch (2.54 mm) in thickness, but they shall be permit- ,A u ted to be less than 0.10 inch (2.54 mm) in thickness if formed 80-7. Indicating. General -use and motor - circuit switches and circuit breakers, where mounted in an enclosure as described or reinforced to provide adequate mechanical strength. Faceplates shall be installed so as to completely cover the wall opening and in Section 380 -3, shall clearly indicate whether they are in the open "off' or closed "on" position. seat against the wall surface. Where these switch or circuit breaker handles are operated Switch plates attached to ungrounded metal boxes are vertically rather than rotationally or horizontally, the up position required to be made of insulating material and are required of the handle shall be the "on" position. to have no exposed conductive parts. 1993 NATIONAL ELECTRICAL CODE HANDBOOK 377 J Article 380 — Switches 380-10. Mounting of Snap Switches. (a) Surface -type. Snap switches used with open wiring on NM Cable insulators shall be mounted on insulating material that will sep- arate the conductors at least 1 /2 inch (12.7 mm) from the surface wired over. (b) Box Mounted. Flush -type snap switches mounted in boxes that are set back of the wall surface as permitted in Sec- ,` 0 C: tion 370 -20 shall be installed so that the extension plaster ears , O are seated against the surface of the wall. Flush -type snap \ Nonmetallic switches mounted in boxes that are flush with the wall surface box or project therefrom shall be so installed that the mounting yoke or strap of the switch is seated against the box. Cooperation is necessary among the building trades (car- \ • 1 0 penters, dry-wall installers, plasterers, etc.) in order for elec- \ °o ' tricians to properly set device boxes flush with the finish o [' surface, thereby ensuring a secure seating of the switch yoke and permitting the maximum projection of switch handles !, ff ■ through the installed switch plate. 4 O 38011. Circuit Breakers as Switches. A hand - operable cir- Equipment 0 mom lt breaker equipped grounding � cu \ q pped with a lever or handle, or a power- operated conductor circuit breaker capable of being opened by hand in the event of a power failure, shall be permitted to serve as a switch if it has the required number of poles. Note: See provisions contained Lvo in Section 240 -81 and Section 240 -83. ° 1' Circuit breakers capable of being hand - operated are required to clearly indicate whether they are in the open, Figure 380-1. The effective grounding of metal face plates can "off," or closed, "on," position. be accomplished by connecting the equipment grounding conduc- See Section 240 - (d) for marking (SWD) for circuit tor provided with the wiring method to a grounding terminal on breakers used as switches for 120 -V and 277 -V fluorescent a metal yoke or strap. lighting circuits. Also see Section 380 -7. (b) To Interrupt Currents. To interrupt currents over 380-12. Grounding of Enclosures. Metal enclosures for 1200 amperes at 250 volts, nominal, or less, or over 600 amperes switches or circuit breakers shall be grounded as specified in Arti- at 251 to 600 volts, nominal, a circuit breaker or a switch of spe- cie 250. Where nonmetallic enclosures are used with metal- cial design listed for such purpose shall be used. sheathed cables or metallic conduits, provision shall be made (c) General -Use Switches. Knife switches of ratings less for grounding continuity. Metal face plates for snap switches shall than specified in (a) and (b) above shall be considered general - be effectively grounded where used with a wiring method that use switches. includes or provides an equipment ground. (FPN): See definition of general -use switch in Article 100. 380-13. Knife Switches. (a) Isolating Switches. Knife switches rated at over 1200 (d) Motor - Circuit Switches. Motor - circuit switches shall be amperes at 250 volts or Tess, and at over 600 amperes at 251 permitted to be of the knife- switch type. to 600 volts, shall be used only as isolating switches and shall not be opened under Toad. (FPN): See definition of a motor - circuit switch in Article 100. 378 NATIONAL ELECTRICAL CODE HANDBOOK 1993 4 Table 9 through Example No. 1(a) Table 10. Expansion Characteristics of PVC Rigid Nonmetallic Conduit Coefficient of Thermal Expansion = 3.38 x 10 in./in./°F Length Change Length Change Temperature in Inches per Temperature in Inches per Temperature Length Inches hes per Temperature in In per Change In 100 ft. of Change In 100 ft. of Change In 100 ft. of Change In 100 ft. of Degrees F PVC Conduit Degrees F PVC Conduit Degrees F PVC Conduit Degrees F PVC Conduit 10 0.4 5 0.2 55 I 2.2 10 0.6 60 2.4 110 4.5 155 6.3 15 0 0.8 65 2.6 115 4.7 160 6.5 2 1.0 70 2.8 120 4.9 165 6.7 30 1.2 75 3.0 125 5.1 170 7.1 35 1.4 80 3.2 130 5.3 175 7. 40 1.6 85 3.4 135 5.5 180 7.3 40 1.8 90 3.6 140 5.7 185 7.5 50 2.8 100 95 3.8 145 5.9 190 7.7 4.1 150 6.1 200 8. 8.1 Examples Computed Load [see Section 220- 10(a)]: General Lighting Load: Selection of Conductors. In the following examples, the . results are generally expressed in amperes. To select conduc- 1500 sq. ft. at 3 volt- amperes per sq. ft = 4500 volt - amperes. for sizes, refer to the 0 to 2000 volt ampacity tables of Article 310, and the Notes that pertain to such tables. Minimum Number of Branch Circuits Required tion 220- 4(b)]: [see Sec - Voltage. For uniform application of Articles 210, 215, and 20, a nominal voltage of 120, 120/240, 240, and 208Y//120 volts General Lighting Load: shall be used in computing the ampere load on the conductor. 4500 volt- amperes _ 120 volts = 37.5 A: This requires three Fractions of an Ampere. Except where the computations 15 A 2 -wire or two 20 A 2 -wire circuits esult in a major fraction of an ampere (0.5 or larger), such frac- Small Appliance Load: Two 2 -wire 20 A circuits [see Section ions shall be permitted to be dropped. 220 -3(b)] Ranges. For the computation of the range loads in these Laundry Load: One 2 -wire 20 A circuit [see Section 220 -4(c)] 'nples, Column A of Table 220-19 has been used. For Ptional methods, see Columns B and C of Table 220 -19. Except Minimum Size Feeder Required [see Section 220- 10(a)]: /here the computations result in a major fraction of a kilowatt Small Appliance Load 3000 volt- amperes General Lighting 1.5 or larger), such fractions shall be permitted to be dropped. 4500 volt amperes SI Units: For SI units: one square foot = 9.093 square Laundry 'eter; one foot = 0.3048 meter. 1500 volt amperes Total General Light and Small In the following examples, loads are assumed to be prop volt-amperes Wires at 100% 9000 volt-amperes 300 -am 3000 volt- amperes - ly balanced on the system. Where loads are not properly 9000 - 3000 = 6000 volt- amperes ilanced, additional feeder capacity may be required. at 35% 2100 volt- amperes 'temple No. 1(a). One - Family Dwellin Net General Lighting and Small g Appliance Load 5100 volt- amperes The dwelling has a floor area of 1500 sq. ft., exclusive of unoc- Range Load (see Table 220 ) 8000 volt amperes Pied cellar, unfinished attic, and open pe porches. Appliances are Dryer Load (see Table 220 - 18) 5500 volt amperes a 12 kW range equ equivalent to 0-- ratings in range and Total Load Neix 18,600 volt amperes 'moons 220-18 and 220 -19. For 120/240 -volt 3 -wire single-phase service or feeder, 18,600 volt- amperes _ 240 volts = 77.5 A. aoec 1993 NATIONAL ELECTRICAL CODE HANDBOOK 921 CHAPTER 11. ELECTRICAL CODE. ARTICLE I. ELECTRICAL REGULATIONS 11 -1 Definitions. 11 -2 National and State Electrical Codes Adopted. 11 -3 Scope of Provisions. 11 -4 Electrical Inspector. 11 -5 Duties of Inspector. 11 -6 Deputy Electrical Inspector. 11 -7 Authority of deputy Inspector. 11 -8 Interpretations of Code by Inspector. 11 -9 Waiver of specific regulations by Inspector. 11 -10 Police and Fire Departments to assist Inspector. 11 -11 Impersonation of Inspector. 11 -12 Authority to arrest possessed by Inspector. 11 -13 Inspection procedure. 11 -14 Right of entry. 11 -15 Obstruction of inspections. 11 -16 Inspector not liable. 11 -17 City not liable. 11 -18 Liability of other crafts. 11 -19 Electrical License and Examining Board. 11 -20 Duties of Board 11 -21 Suspension and revocation of license. 11 -22 Licenses and certificates for electricians required. 11 -23 Classification of certificates and licenses. 11 -24 Application for certificates and fees. 11 -25 Applicants for Class 1 certificates. 11 -26 Applicants for Class 2 and Class 3 certificates. 11 -27 Applications for Type C electrical contractor's license. _ 11 -28 Application for Type M electrical maintenance license. 11 -29 Dual licenses prohibited. 11 -30 Application for Type S license. 11 -31 Provisions applicable to all electrical licenses. 11 -32 Permits for electrical work required. 11 -33 Application for permits. 11 -34 Optional arrangement for Type M licensee. 11 -35 Issuance of permits. 11 -36 Work without permits. 11 -37 Lapse of permit. 11 -38 Plans and specifications may be required to be submitted. 11 -39 Permit fees. 11 -40 Authorization for electric supply required. 11 -41 Approval of electrical equipment. 11 -42 Utilization of equipment. 11 -43 Sale of electrical equipment. 11 -44 Unsafe or illegal electrical equipment. 11 -45 Seizure of electrical equipment. 11 -46 Installation requirements. 11 -47 Residences; electrical construction specifications. 11 -48 Residential garages. 11/1 treated within the Wisconsin State Electrical Code, the Electrical Inspector shall have the authority to establish installation standards. (B) Buildings Not Specifically Regulated In buildings and structures not otherwise herein regulated, rigid metal conduit, electrical metallic tubing, cellular metal floor raceways, metal underfloor raceways or under plaster extensions shall be used for concealed wiring; provided, however, that flexible metal conduit or, by special permission of the Electri- cal Inspector, armored cable may be installed in spaces which have been permanently closed in by the structure or finish of any building which has been completed for at least ninety (90) days and which is not judged as electrically hazardous by the Electri- cal engineer. SECTION 11 -47 RESIDENCES: ELECTRICAL CONSTRUCTION SPECIFICATIONS. (A) Metallic Equipment Rig — ' id metal conduit; electrical metallic tubing armored cable, ENT, PVC, or flexible metal conduit shall be used for all concealed wiring in all commercial buildings, and buildings over three (3) stories or floors above grade. (B) Non - metallic Equipment Non - metallic sheathed cable with an integral ground wire may also be used in such buildings when installed as follows: (1) Shall be used for concealed wiring only. This includes basements, cellars, under -floor crawl- space, and usable attics only if all such spaces have been permanently closed by the structure or finish of the building or structure. (2) An exposed length of not more than eighteen (18) inches shall be permitted for connection to a metallic protected system when emerging from concealed to surface wiring. (3) Only such straps and box clamp devices shall be used which provide flat parallel pressure on both sides of the cable and each cable shall have its individual connector except as UL approved. SECTION 11 -48 RESIDENTIAL GARAGES. In residential garages all wiring must be in rigid conduit or electric metallic tubing, PVC Schedule 40, except that use of armored cable or nonmetallic sheathed cable, ENT with an integral ground wire will be permitted where the walls and ceilings are covered with a permanent finishing material. 11/19 SECTION 11 -49 BASEMENTS. In basements, sub - basements, cellars, sub- cellars and any accessible space under the lower floor, exposed wiring, i.e., wiring which is not protected by a permanent surfacing such as plaster, etc., shall be rigid metal conduit, electrical metallic tubing, auxiliary gutter, busways, surface metal raceways, PVC Schedule 40, and (by special permission only) flexible metal conduit. No armored cable (BX) non- metallic sheathed cable or flexible metal conduits shall be exposed in such locations; except that when armored cable, nonmetallic sheathed cable or flexible metal conduit is allowed by this Chapter concealed in other parts of the building or structure, such armored cable, nonmetallic sheathed cable or flexible metal conduit may be exposed or extended no more than eighteen (18) inches into basements, sub- basements, cellars, etc. in order to connect to the metallic protected wiring system. SECTION 11 -50 SERVICES. (A) Minimum Size Sin le Phase Service Requirements Ex by special pe missi n the authority enforcing this Code, the minimum size single phase service permitted for any building regulated in Section 11 -49 shall be one hundred (100) ampere and shall include a one hundred ampere load- center provid- ing not less than 16 circuit full size breakers. (B) Service Entrance Rizers Galvanized rigid met conduit, electrical metallic tubing, PVC Schedule 40, or busways shall be used for all service entrance conductors. 11/20 (C) Entrance Cover Required An approved entrance cover or sill plate shall be provided where the cable enters the building. (D) Periscope Service (1) Where service drops are be attached above the eaves of a building necessitating the use of so- called periscope serv- ice, the supporting mast shall in no instance be made of wood but shall be two (2) inch or larger galvanized rigid conduit or by special permission of the Electrical Inspec- tor, angle, channel, or similar steel support may be provid- to (2) Where two (2) inch or larger conduit is utilized as a serv- ice mast, a full ten (10) foot length must be installed before reducing to a smaller size and in instances where the service is excessively high, enough conduit must be added so as to project downward at least five (5) feet from the lower edge of the eave.before reducing to a smaller size. (3) Clamps or straps shall be used spaced as per National Elec- tric Code. Galvanized wood screws must be used on wood siding and approved anchors on masonry walls or equipment approved by the inspector. (E) Accessibility of Service Equipment Service equipment or panelboards shall be accessible at all times and shall not be permitted in clothes closets, coalins, toilets or any place which is not readily accessible. (F) Damaged Service (1)In the event of damage to an electrical service, whether by storm, deterioration, vandalism, or other causes, all electrical service, 60 Amperes or less shall be replaced with a minimum of 100 Ampere service. (2) At the time of service change, the wiring of the dwelling shall also be brought up to at least the requirements of the Minimum Housing Code. (See Chapter 16 of this Code.) (3) Failure to comply with this Section shall result in the disconnection of the electrical service as provided in Section 11 -44 of this Code. SECTION 11 -51 UNDERGROUND SERVICES. (A) Conductor Cable Specifications Cables of one or more conductors for direct burial in the earth shall be Type USE (Underground Service Entrance) except that branch circuit and feeder cable may be Type OF (Underground Feeder). If single conductor cables are installed, conductors of each service, feeder, subfeeder or branch circuit shall be run 11/21 (d) All openings to a building which might provide an entry for rodents shall be effectively protected at all times so as to prevent their entry. (3) Electrical service (a) Every habitable room shall contain at least two (2) separate wall -type electric convenience outlets or one (1) such convenience outlet and one (1) ceiling -type or wall -type electric fixture; and every water closet compartment, laundry room, furnace room and public hall shall contain at least one (1) ceiling or wall -type electric fixture. Every bathroom shall contain one wall convenience outlet and one wall or ceiling light fixture. Every such outlet and fixture shall be properly installed and shall be maintained in a good and safe working condition and shall be connected to the source of the electric power in a safe manner. (b) In every building, accommodating two (2) or more dwelling units using the same corridors and stairways, adequate lighting shall be provided in such corridors and stairways when needed. Such lighting shall be operated by any of the following means: (i) Light switches a) Corridors - By conveniently located light switches. b) Stairs - At least the equivalent of a three - way light switch system located at the top and bottom of all stairways. (ii) Any automatic type of operation which will maintain adequate lighting at all times, either natural or artificial. (c) Electrical service panels shall be readily accessible to all occupants in a dwelling without passing through her dwelling unit as required by the National Electri- cal Code as may be amended from time to time. (d) Exterior lighting shall be required to illuminate exterior entry /exit steps in or leading to dwelling units. (4) Natural Lighting Every habitable room shall be provided with window areas equal to at least eight percent (8 %) of the floor area. 16/31 L