3RT5QY4V42SU
In article " Receptacle Branch Circuit Design Calculations – Part Three ", I stated that a Receptacle in dwelling units may serve one of the following loads:
 Generaluse Receptacle Loads,
 Small appliance Loads,
 Laundry Load,
 Cloth dryer Load,
 Household cooking appliances load,
 Fastenedinplace Appliance loads,
 Heating and air conditioning loads,
 Motor loads.
I explained the first five types in the following articles:
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 articles for more information:
6 Fastenedinplace Appliances branch circuits
Definition:
The term appliance designates utilization equipment
commonly built in standardized types and sizes and installed as a unit to
perform specific function(S) such as clothes washing, air conditioning, food
mixing, deep frying, etc.
Some examples of appliances that are fastened in place
whether direct wired or cord and plug connected include dishwashers,
kitchenwaste disposers, trash compactors, attic fans and water heaters (see
below image).

Definitions:

Rule#1: Not
FastenedinPlace Appliances (see below image)
As per NEC section 220.53, electric
ranges, clothes dryers, spaceheating equipment or air conditioning equipment
must not be included with the number of appliances that are fastened in place.
Also, All portable small Appliances for kitchen and others are not
FastenedinPlace Appliances.

Rule#2: Location of receptacle outlet used for Electric Appliances
Appliance receptacle
outlets installed in a dwelling unit for specific appliances, such as laundry
equipment, shall be installed within 1.8 m (6 ft) of the intended location of
the appliance.

Important!!!
The load for an appliance
is simply the ampere rating of that appliance which may be indicated on its
nameplate and will be used in branch, feeder and service load calculations.

6.1 Applied NEC Rules for Fastenedinplace Appliances load
There are many NEC rules that control the location and load of Fastenedinplace appliances including:
6.2 Calculation of Fastenedinplace Appliances load
 210.23(A) Permissible Loads for 15 and 20Ampere Branch Circuits
 220.14 (A) Specific Appliances or Loads in All Occupancies
 220.53 Appliance Load in Dwelling Unit
 220.82(B)(3) Optional Feeder and Service Load Calculations of General Loads in Dwelling Unit
6.2 Calculation of Fastenedinplace Appliances load
A For feeder and service calculation purposes
First: As per NEC Standard calculation method:
Important!!!
Kilovoltamperes (kVA) shall be considered
equivalent to kilowatts (kW) for Fastenedinplace Appliances.

Rule#3: Calculation of Fastenedinplace Appliances load
As per NEC section, 220.53, It shall be permissible
to apply a demand factor of 75 % to the nameplate rating load of four or more
appliances fastenedinplace, that are
served by the same feeder or service in a onefamily, twofamily, or
multifamily dwelling.

Important!!!
No derating is allowed when there are only one, two,
three fastenedinplace appliances.

Example#1:
A onefamily dwelling will have two feeders supplied by the service. One feeder will provide power to a water heater and two attic ventilation fans. The other feeder will provide power to a dishwasher, a kitchenwaste disposer and a trash compactor. Where the 75 % demand factor to be applied?
Solution:
Since only three appliances are on each feeder, it is not permissible to apply the 75 % demand factor to either feeder load calculation.
The demand factor can be applied to the service load calculation because it will supply power to six fastenedinplace appliances.
Example#2:
What is the appliance load contribution, for a house that has a 1.2 KVA dishwasher, a 0.76 KVA garbage disposer, a 1.1 KVA trash compactor and a 4.5 KVA water heater?
Solution:
Step#1: find the total load or the Fastenedinplace Appliances
Total load = 1.2+0.76+1.1+4.5 = 7.56 KVA
Step#2: if the number of the Fastenedinplace Appliances is four or more, apply the 75% demand factor.
Demand load = 7.56 x 75% = 5.67 KVA
Rule#4: Calculation of Fastenedinplace Appliances load For Multifamily Dwelling
In a multifamily dwelling, the four or more
fastenedinplace appliances do not have to be on the same feeder for each
dwelling unit. In this case, the 75% demand factor will not apply to the
feeder for each dwelling unit but it must be applied to the multifamily
dwelling service.

Example#3:
A 4.5kilowatt (kW), 240volt (V) water heater will be installed in each unit of a fourunit multifamily dwelling. The water heaters are the only fastenedinplace appliance in this multifamily dwelling. One service will supply all four units. Using the standard method, what is the service load (after applying the demand factor) for fastenedinplace appliances?
Solution:
Each unit has only one fastenedinplace appliance, the 75% demand factor will not apply to the feeder for each dwelling unit.
But there will be four fastenedinplace appliances on the multifamily dwelling service. Therefore, applying the 75 percent demand factor is permissible.
The service load for these water heaters = 4x4.5x0.75 = 13.5 KW
Second: As per NEC Optional calculation method:
Rule#5: Application of NEC Optional calculation method
NEC Optional calculation method will be used if the
following condition is verified:

Important!!!
If the serviceentrance ampacity calculated by the
optional method is less than 100A, recalculate with using the standard
method.

Important!!!
In NEC Optional calculation method, for a
multifamily dwelling, Table 220.84 “Optional Calculations — Demand Factors
for Three or More Multifamily Dwelling Units” will be used if the following
conditions are verified:

Important!!!
The optional calculation can be used, provided all
of the conditions for using table 220.84 listed above are met. Otherwise, the
calculation for the multifamily dwelling is performed by using standard
calculation method.

Rule#6: Calculation of Fastenedinplace Appliances load as per NEC Optional calculation method
In Optional calculation method, note the following:

Important!!!
The fastenedinplace appliances Load including
water heater is given, do not include water heat load to the general load as
per 220.82(B)(3)d . But if the water heater was not included with the
fastenedinplace appliances, add the nameplate rating of the water heater to
the general loads covered in 220.82(B).

Example#4:
what is the optional method service load calculation for a onefamily dwelling with the following fastenedinplace appliances: a dishwasher rated 10 amperes (A) at 120 volts (V); a horsepower, 120V kitchen waste disposer; a trash compactor rated 7.5A at 120V; and a 4.5 kilowatts (kW), 240V water heater?
Solution:
The loads in KVA will be as follows:
The dishwasher load = 10A x120V = 1,200 VA = 1.2 KVA
Kitchen waste disposer load = 9.8A x 120V = 1,176 VA = 1.176 KVA
The compactor load = 7.5A x 120V = 900 VA = 0.9 KVA
The water heater load = 4,500W = 4,500 VA = 4.5 KVA
The optional method service load = 1.2 + 1.176 + 0.9 + 4.5 = 7.776 KVA
Example#5:
Find the optional method service load calculation for a 12unit multifamily dwelling with each unit containing the following fastenedinplace appliances: a dishwasher rated 10 amperes (A) at 120V; 9.8 A, 120V kitchen waste disposer, and a 4.5 kW, 240V water heater.
Solution:
The loads in KVA will be as follows:
The dishwasher load = 10A x 120V = 1,200 VA.
The kitchen waste disposer load = 9.8A x 120V = 1,176 VA.
Water heater load = 4.5 KW x1,000 = 4,500 W = 4500 VA
The fastenedinplace appliance load for each unit = 1,200 + 1,176 + 4,500 = 6,876 VA
Since there are 12 units, multiply the appliance load by 12
The fastenedinplace appliance service load for the building = 12 x 6,876 VA = 82,512 VA
Apply the Table 220.84 (in below image) for demand factor, of Multifamily dwelling, since there are 12 units, the demand factor will be 41%.
The optional method demand load for this building = 82,512 VA x 41% = 33,830 VA
B For branch circuit requirements (conductor ampacity & size and overcurrent protection) calculation
Rule#7: Combination of Fastenedinplace Appliances with other loads on
a branch circuit
As per NEC section 210.23(A), The total rating of
utilization equipment fastened in place, other than luminaires, shall not
exceed 50 percent of the 15 and 20Ampere Branch Circuits branchcircuit
rating where lighting units, cordandplugconnected utilization equipment
not fastened in place, or both, are also supplied.

Rule#8: Rating of Fastenedinplace Appliances Outlet
As per NEC section 220.14 (A), an outlet for a
specific appliance or other load not covered in 220.14(B) through (L) shall
be calculated based on the ampere rating of the appliance or load served.

Example#6:
What is the branchcircuit load for a 10ampere, 120volt dishwasher in a dwelling?
Solution:
Since the rating on the nameplate is 10 amperes, the branchcircuit load for this dishwasher is 10 amperes.
Important!!!
Using fastenedinplace equipment is not permitted
for the smallappliance branch circuits, laundry branch circuits, and
bathroom branch circuits required in a dwelling unit and these branch
circuits shall supply only their receptacle outlets required by the code.

Important!!!
Small loads, such as those of 1440 voltamperes or
less and motors of less than 1⁄4 horsepower, are limited to 120 volt
circuits.

In the next article, I will explain branch circuits that serve other types of loads. Please, keep following.
Post a Comment
Leave a comment to help all for better understanding