Sunday, February 14, 2010

PEC REQUIREMENTS FOR ADEQUATE WIRING IN SINGLE AND MULTI-FAMILY DWELLING UNIT

GENERAL LIGHTING LOADS BY OCCUPANCIES
(Table 1.1)

* All receptacle outlets of 20-ampere or less in one-family, two-family and multifamily dwellings and in guest rooms of hotels and motels shall be considered as outlets for general illumination, and no additional load calculations shall be required for such outlets.

** In addition a unit load of 8 volt-amperes per square meter shall be included for general purpose receptacle outlets when the actual number of general purpose receptacle outlets is unknown.


FEEDER DEMAND FACTORS FOR GENERAL LIGHTING LOAD AND SMALL APPLIANCE LOAD

(Table 2.1)


*The demand factors of this table shall not apply to the computed load of feeders to areas in hospitals, hotels, and motels where the entire lighting is likely to be used at one time, as in operating rooms, ballrooms, or dining rooms.




DEMAND FACTOR FOR HOUSEHOLD ELECTRIC CLOTHES DRYER

(Table 3.1)






DEMAND LOADS FOR HOUSEHOLD ELECTRIC RANGES,

WALL-MOUNTED OVENS, COUNTER-MOUNTED COOKING UNITS, AND OTHER HOUSEHOLD COOKING APPLIANCES OVER 1.75 KW RATING.

COLUMN A TO BE USED IN ALL CASES EXCEPT AS

OTHERWISE PERMITTED ON NOTE 3 BELOW

(Table 4.1)



Note: Over 12 kW through 27 kW ranges all of same rating. For ranges individually rated more than 12 kW but not more than 27 kW, the maximum demand in Column A shall be increased 5 % for each additional kW of rating of major fraction thereof by which the rating of individual ranges exceeds 12 kW.


Note 2: Over 8.75 kW through 27 kW ranges of unequal ratings. For ranges individually rated more than 8.75 kW and of different ratings but no exceeding 27 kW, an average of value of rating shall be computed by adding together the ratings of all ranges to obtain the total connected load (using 12 kW for any range rated less than 12 kW) and dividing by the total number of ranges; and then the maximum demand in column A shall be increased 5 percent for each kW or major fraction thereof by which this average value exceeds 12 kW.



Note 3: Over 1.75 kW through 8.75 kW. In lieu of the method provided in column A, it shall be permissible to add the nameplate ratings of all ranges rated more than 1.75 kW but not more than 8.75 kW and multiply the sum by the demand factors specified in column B or C for the given numbers of appliances.


Note 4: Branch circuit load. It shall be permissible to compute the branch-circuit load for one range In accordance with Table 3.3.2.10. the branch-circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance. The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens, all supplied from a single branch circuit and located in the same room, shall be computed by adding the nameplate ratings of the individual appliances and treating this total as equivalent to one range.


Note 5: This table also applies to household cooking appliances rated over 1.75 kW and used in instructional programs.






FULL LOAD CURRENT IN AMPERES

SINGLE PHASE ALTERNATING - CURRENT MOTORS

(Table 4.1)





FULL-LOAD CURRENT

TWO-PHASE ALTERNATING CURRENT MOTORS (4-WIRE)

(Table 5.1)



FULL-LOAD CURRENT

THREE-PHASE ALTERNATING-CURRENT MOTORS

(Table 6.1)





CONVERSION TABLE OF LOCKED-ROTOR CURRENTS

FOR SELECTION OF DISCONNECTING MEANS AND CONTROLLERS

AS DETERMINED FROM HORSEPOWER AND VOLTAGE RATING

(Table 7.1)




MAXIMUM RATING OR SETTING OF MOTOR BRANCH-CIRCUIT

SHORT-CIRCUIT AND GROUND-FAULT PROTECTIVE DEVICES

(Table 8.1)






ALLOWABLE AMPACITIES OF INSULATED CONDUCTORS

RATED 0-2000 VOLTS, 60º C TO 90ºC

NOT MORE THAN THREE CONDUCTORS IN RACEWAY OR CABLE OR EARTH (DIRECTLY BURIED), BASED ON AMBIENT

TEMPERATURE OF 30ºC

(Table 9.1)




AMPACITY CORRECTION FACTORS

(Table 10.1)






ALLOWABLE AMPACITIES OF SINGLE INSULATED

CONDUCTORS, RATED 0-2000VOLTS, IN FREE AIR

BASED ON AMBIENT AIR TEMPERATURE OF 30ºC

(Table 11.1)





AMPACITY CORRECTION FACTORS

(Table 12.1)


+ Unless otherwise specifically permitted elsewhere in this Code, the over current protection for conductor types marked with an obelisk (+) shall not exceeds 15 amperes for 2.0 mm2, 20 amperes for 3.5 mm2, and 30 amperes for 5.5 mm2 copper; or 15 amperes for 3.5 mm and 25 amperes for 5.5 mm2 aluminum and copper clad aluminum.





ALLOWABLE AMPACITIES OF THREE SINGLE INSULATED

CONDUCTORS, RATED 0-2000VOLTS, 150º TO 250ºC, IN

RACEWAY OR CABLE BASED ON AMBIENT AIR

TEMPERATURE OF 40ºC

(Table 13.1)





AMPACITY CORRECTION FACTORS


(Table 14.1)




ALLOWABLE AMPACITIES FOR SINGLE INSULATED

CONDUCTORS, RATED 0-2000VOLTS, 150º TO 250ºC, IN

FREE AIR BASED ON AMBIENT AIR

TEMPERATURE OF 40ºC


(Table 15.1)




AMPACITY CORRECTION FACTORS


(Table 16.1)



EXCEPTIONS (based on PEC requirements)

1. The small appliance appliance branch circuit required in a dwelling unit shall supply only the receptacle outlets specified in that section.
(b.) 25- and 30-Ampere Branch Circuits. A 25- or 30-ampere branch circuit shall be permitted to supply fixed lightning units with heavy-duty lamp holders in other dwelling unit(s) or appliances shall not exceed 80 percent of the branch-circuit ampere rating.
(c.) 40- and 50-Ampere Branch Circuits. A 40- and 50-ampere branch circuit shall be permitted to supply fixed lighting units with heavy-duty lamp holders or infrared heating units in other than dwelling units or cooking appliances that are fastened in place in any occupancy.


Receptacle Outlets required
(a) General. where flexible cords are used.

2. where flexible cords are specifically permitted to be permanently connected, and are so connected in boxes or fittings approved for the purpose, it shall be acceptable to omit receptacles on such equipment.

(b) Dwelling units. In every kitchen, family room, dining room, breakfast room, living room, parlor, library, den, sun room, bedroom, recreation room, or similar rooms, receptacle outlets shall be installed so that no point along the floor kine in any wall space is more than 1800 mm, measured horizontally, from an outlet in that space, including any wall space 600 mm or more in width and the wall space occupied by sliding panels in exterior walls. The wall space afforded by fixed room dividers, such a free-standing bar type counters, shall be included in the 2 meter measurement.

In kitchen and dining areas, a receptacle outlet shall be installed at each counter space wider than 300 mm. Counter top spaces separated by range tops, refrigerators, or sinks shall be considered as separate counter top spaces. Receptacles rendered inaccessible by appliances fastened in place or appliances occpying dedicated space shall not be considered as these requires outlets.

Receptacles outlets shall, in so far as practicable, be spaced equal distances apart. Receptacle outlets in floors shall not be counted as part of the required number of receptacle outlet unless located close to the wall.

At least one wall receptacle shall be installed in the bathroom adjacent in the basin location.

For a one-family dwelling, at least one receptacle outlet shall be installed outdoors.

For a one-family dwelling, at least one receptacle outlet in addition to any provided for laundry equipment, shall be installed in each basement and in each attached garage.

Outlets in other section of the dwelling unit for special appliances, such as laundry equipment, shall be placed within 1800 mm of the intended location of the appliance.

At least one receptacle outlet shall be installed for the laundry.

3. In a dwelling unit that is an apartment or living area in a multifamily dwelling where laundry facilities are provided on the premises that are available to all building occupancies, a laundry receptacle shall not be required.

4.In other than one-family dwellings where laundry facilities are not be installed or permitted, a laundry receptacle shall not be required.

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 600 or more mm wide shall be treated individually and separately from the other wall spaces within the room. A wall space shall be permitted to include two or more walls or a room(around corners) where unbroken at the floor line.

The receptacle outlets required by this section shall be in addition to any receptacle that is part of any lighting fixture or appliances, located within cabinet or cupboard, or located over 1600 mm above the floor.

5. Permanently installed electric baseboard heaters equipped with factory installed receptacle outlets, or outlets provided as a separate assembly by the manufacture, shall be permitted as the required outlet or outlets for the wall space utilized by such permanently installed heaters. Such receptacle outlets shall not be connected to the heater circuits.

Lighting Outlets Required:

(a) Dwelling units: At least one wall switch controlled lighting outlet shall be installed in every habitable room, in bathrooms, hallways, stairways and attached garage: and at outdoor entrances

At least one lighting outlet shall be installed in an attic, underfloor space, utility room and basement only wher these spaces are used for storage or containing equipment requiring servicing.

6. In habitable rooms, other than the kitchen, one or more receptacles controlled by a wall switch shall be permitted in lieu of light outlets

7. In hallways, stairways, and at outdoor entrances remote, central, or automatic control of lighting shall be permitted.


FEEDERS:

Minimum size or rating. Feeder conductors shall have an ampacity not lower than required to supply the load . The minimum sizes shall be as specified in (a) and (b) below under the conditions stipulated. Feeder conductors for a one family dwelling or amobile home need not be larger than service entrance conductors.

(a) For specified circuits. The feeder conductors shall not be smaller than 5.5 square mm where the load supplied consists of the following number and types of circuits: (1) Two or more 2-wire branch circuits supplied by a 2-wire feeder. (2) MOre than two 2-wire branch circuits supplied by a 3-wire feeder (3) Two or more 3-wire branch circuits supplied by a 3-wire feeder

(b) ampacity relative to service entrance conductors. The feeder conductor ampacity shall not be lower than that of the service-entrance conductors 14 square mm or smaller.

(c) Overload feeders. Where at any time feeder conductors are or will be overloaded the feeder conductors shall be increased in ampacity to accommodate the ctual load served.

OPTIONAL CALCULATION - MULTIFAMILY DWELLING
(a) It shall be permissible to compute the feeder or service load of a multifamily dwelling where all the following conditions are met:

(1) No dwelling unit is supplied by more than one feeder
(2) Each dwelling unit is equipped with electric cooking equipment.

EXCEPTION: When the computed load for multifamily dwelling under the section without cooking load exceeds that computed under this section for the identical load plus electric cooking exceeds that computed for the identical load plus the electric cooking, the lesser of the loads may be used.

(3) Each dwelling unit is equipped with either electric space heating or air conditioning or both

Feeders and service-entrance conductors whose demand load is determined by this optional calculation shall be permitted to have the neutral load determined by this section

the connected load to which the demand factors apply shall include the following:

(1)1500 watts for each 2-wire, 20 A small appliance branch circuit and each laundry branch circuit

(2) 24 watts per square meter for general lighting and general use receptacles

(3) The nameplate rating of all appliances that are fastened in place, permanently connected or located to be on a specific circuit, ranges, wall mounted ovens, counter-mounted cooking units, clothes dryer, water heaters and space heaters

If water heater elements are so interlocked that all elements cannot be used at the same time, the maximum possible load shall be considered the nameplate load.

(4)The nameplate A or kVA rating of all motors and of all low-power factor load.

(5) The larger of the air conditioning load or the space heating load.






2 comments:

  1. Great blog and this information is very useful to everyone. Electrical Wiring

    ReplyDelete
  2. nice blog.. keep posting electrical stuff. thanks

    ReplyDelete

 
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