Receptacle Branch Circuit Design Calculations – Part Five


In the previous article " Receptacle Branch Circuit Design Calculations – Part Four ", I explained General-use Receptacle branch circuits. 

Also, in previous article " Receptacle Branch Circuit Design Calculations – Part Three ", I stated that a Receptacle in dwelling units may serve one of the following loads: 

  1. General-use Receptacle Loads,
  2. Small appliance Loads,
  3. Laundry Load,
  4. Fastened-in-place Appliance loads,
  5. Cloth dryer Load,
  6. Household cooking appliances load,
  7. Heating and air conditioning loads,
  8. Motor loads.


In the following paragraphs, I will explain Where and how to distribute each load outlets in a dwelling building as per NEC code. 
You can review the following previous articles for more information: 




2- Small Appliances Branch circuits


2.1 Applied NEC Rules for small appliances branch circuits:


There are many NEC rules that control the number, location and type of small appliances branch circuits including:

  • 210.8 A(6) Ground-Fault Circuit-Interrupter Protection for Personnel in Kitchens, 
  • 210.11(C)(1) Required Branch Circuits in Dwelling Units for Small-Appliance Branch Circuits, 
  • 210.52(A)(4) Dwelling Unit Receptacle Outlets for Countertop Receptacles, 
  • 210.52(B) Dwelling Unit Receptacle Outlets for Small Appliances, 
  • 210.52(C) Dwelling Unit Receptacle Outlets for Countertops, 
  • 220.52 (A) Small-Appliance Circuit Load in Dwelling Unit. 



2.2 Rules controlling small appliances Branch Circuits:

Rule#1: number of small appliance branch circuits

In each dwelling unit, two or more 20-ampere small-appliance branch circuits shall be provided.



Rule#2: areas served by small appliances branch circuits

All Receptacle Outlets In the kitchen, pantry, breakfast room, dining room, or similar area of a dwelling unit which serve Portable appliances used at a kitchen counter, such as toasters, coffee makers, skillets, mixers, and the like and after applying exceptions made by rules#6.



Rule#3: Receptacle Outlets served by small appliances branch circuits (see fig.1)

The following receptacle outlets are permitted to be served by small appliance branch circuits:
  1. All wall and floor receptacle outlets covered by 210.52(A) after applying exceptions made by rules#6,
  2. All countertop outlets covered by 210.52(C),
  3. Receptacle outlets for refrigeration equipment (see Rle#4).
  4. Electric clock in any of the areas specified in Rule#2,
  5. Supplemental equipment and lighting on gas-fired ranges, ovens, or counter-mounted cooking units.


The small appliance branch circuits are not permitted to serve any other outlets, such as might be connected to exhaust hoods or fans, disposals, or dishwashers.



Rule#4: Receptacle outlet for refrigeration equipment (see fig.1)

The receptacle outlet for refrigeration equipment located in a kitchen or similar area shall be permitted to be supplied from one of the following circuits:
  1. 20-A small appliance branch circuit,
  2. An individual branch circuit rated 15 amperes or greater especially, when the receptacle outlet for the refrigerator is located so that it cannot be used to serve countertop surfaces.


Fig.1



Rule# 5: Distribution of small-appliance branch circuits (see fig.1)

Small-appliance branch circuits must supply the required receptacles by rule#3 in the following way:

  • The counter area receptacle outlets in the kitchen are required to be supplied by minimum two small-appliance branch circuits.
  • The wall receptacle outlets in the kitchen and dining room are permitted to be supplied by one or both of the small-appliance branch circuits that supply the counter area.
  • If there are many kitchens in same dwelling unit, no small-appliance branch circuit shall serve more than one Kitchen.



Rule#6: floor Receptacles (see fig.1)

Receptacle outlets in floors shall not be counted as part of the required number of general-purpose receptacle outlets unless located within 450 mm (18 in.) of the wall. Otherwise, these Floor Receptacles will be counted as part of the small appliance branch circuits.



Rule#7: kitchen and dining areas counters receptacles other than that used for small appliances (see fig.1)

Receptacle outlets installed to serve kitchen or dining area counters (for small appliances) cannot also be used as general-use receptacles for an adjacent wall space and in this case general-use receptacle branch circuits must be added to serve such locations.



Rule#8:general-purpose Switched receptacles (see fig.1)

Switched receptacles supplied from general-purpose 15-ampere branch circuits are permitted to be located in kitchens, pantries, breakfast rooms, and similar areas.




2.3 rules controlling distribution of receptacle outlets of countertop spaces


Countertops may be found In kitchens, pantries, breakfast rooms, dining rooms, and similar areas of dwelling units, these countertops have receptacle outlets which will be distributed in the countertop space as per the following rules: 





Rule#9: spacing of Countertop receptacles (see figs.2,3)

A receptacle outlet shall be installed at each wall countertop space that is 300 mm (12 in.) or wider And spaced so that no point along the wall line is more than 600 mm (24 in.) measured horizontally from adjacent receptacle outlet in that space.



Fig.2


Rule#10: a sink, range, or counter-mounted cooking unit installed in Countertop (see figs.2,3)

Receptacle outlets shall not be required on a countertop wall directly behind a range, counter-mounted cooking unit, or sink.



Fig.3


Rule#11: dividing a Countertop (see figs.2,3)

If the space depth behind a sink, range, or counter-mounted cooking unit is 12 in. or more or 18 in. or more (depending on the counter configuration), the countertop is still one space, and in this case the wall length behind a sink, range, or counter-mounted cooking unit must be included in measuring the total wall counter space to calculate the number of required Receptacle(s) for this countertop.

But if the space depth behind a sink, range, or counter-mounted cooking unit is less than 300 mm (12 in.), countertop will be considered as two separate standalone countertops and rules #1 will be applied for each separate countertop.


Important!!!
Rule#11 will apply for island and peninsular countertop  (see fig.4) with a short dimension of at least 12 in. and a long dimension of at least 24 in.  Noting that the measurement of a peninsular- type countertop is from the edge connecting to the non-peninsular counter.

Peninsular countertop definition: kitchen is simply an island anchored to a wall or line of cabinets. It may be used as a breakfast bar, seating area or just extra countertop and storage space.



Fig.4



Rule#12: Receptacle locations on or above Countertop

Receptacle outlets shall be located on or above, but not more than 500 mm (20 in.) above, the countertop.



Rule#13: Receptacle locations below Countertop

Receptacle outlets shall be permitted to be mounted not more than 300 mm (12 in.) below the countertop with the following conditions:
  1. There are no means to mount a receptacle within 500 mm (20 in.) above the countertop, such as an overhead cabinet.
  2. Receptacle will be Accessible for use,
  3. The countertop edge (beside the wall) extends less than 150 mm (6 in.) beyond its support base.
  4. The countertop is flat across its entire surface (no backsplashes, dividers, etc.)



Important!!!
Multi-outlet assemblies (see fig.5) shall be permitted to be to be used as the required countertop receptacle outlet(s) and it will be installed as one of the following ways:
  1. Installed directly on the countertop
  2. Installed on the bottom of the upper cabinets


Fig.5


Rule#14: Guest Rooms and Guest Suites in dwelling units and that are provided with permanent provisions for cooking (see fig.6)

Guest rooms and guest suites that are provided with permanent provisions for cooking shall have branch circuits installed in the cooking area to meet the above rules#1 to #13.


Fig.6



2.4 Calculation of general-use receptacles load


A- For feeder and service calculation purposes:


As per NEC section 220.52(A), in each dwelling unit, the load shall be calculated at 1500 volt-amperes for each 2-wire small-appliance branch circuit. this load will be added for other loads to perform the feeder and service calculations.



B- For branch circuit requirements (conductor ampacity & size and over-current protection) calculation


This will be explained in coming articles, however you can review the calculation for maximum number of allowable receptacles on a branch circuit which was discussed before in previous article " Receptacle Branch Circuit Design Calculations – Part Three ".



2.5 How to specify the required Type of receptacles for small appliances branch circuits?


1- GFCI Type


As per NEC section 210.8 A (6), where the receptacles are installed to serve the countertop kitchen appliances around a kitchen sink must be GFCI Type. See fig.7. 
Fig.7


Important!!!
I explained in rule#5 in previous article “Receptacle Branch Circuit Design Calculations – Part Five“ that a general-use receptacle branch circuits must be added to kitchens to serve Receptacles installed for disposals, dishwashers, and trash compactors. These receptacles are not required to be GFCI type. The same is for receptacle(s) installed behind a refrigerator to supply that appliance, not the countertop, and will not be GFCI type.



Important!!!
According to 406.5(E), receptacles installed to serve countertops cannot be installed in the countertop in the face-up position because liquid, dirt, and other foreign material can enter the receptacle.



2- Tamper-Resistant type


Tamper-Resistant receptacles are intended to increase safety for children. All non-locking type 125- volt, 15- and 20-ampere receptacles shall be listed tamper resistant receptacles. The Receptacles in the following locations shall not be required to be tamper-resistant: 

  • Receptacles located more than 1.7 m (51⁄2 ft) above the floor (these receptacles are not accessible and well out of reach of small children). 
  • Receptacles that are part of a luminaire or appliance. 
  • A single receptacle or a duplex receptacle located within dedicated space for appliance that, in normal use, is not easily moved from one place to another ( like dishwashers, refrigerators, washing machines, and the like ) 


In the next article, I will explain Receptacle branch circuits that serve other types of loads. Please, keep following.


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