NEC OPTIONAL DWELLING LOAD CALC - RANGE MANUFACTURERS RATING

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rodma808

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honolulu
Do I really use 14.3KW for the range load for the optional Calculation since name plate data is suppose to be used?

The manufacturer's data is as follows: 240V, 1 phase, 14.3KW. Minimum Circuit Required: 40A.

14.3KW at 240V is 59.58Amps. Obviously, 40A will limit this amount load.

(I thought this was a typo, but i noticed other manufacturer also have similar kw ratings and circuit sizing).

With this, Do I really use 14.3KW for the optional Calculation since this is the name plate? Does not make sense.

Would appreciate you opinion.

rodma808
 

augie47

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Tennessee
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State Electrical Inspector (Retired)
You do use the nameplate rating for your initial calculation but note the 40% multiplier from 220.82(B)
 

rodma808

Member
Location
honolulu
You do use the nameplate rating for your initial calculation but note the 40% multiplier from 220.82(B)


Thanks for the reply, but still puzzled. I fully understand the 40% demand factor used in the optional calc.
Let me rephrase the question:

1.On the nameplate, why does the KW rating exceed the circuit breakers capacity?
2.If the electrical system will be limited by the 40A circuit breaker, then why use the KW rating in calc? The electrical system will never see the full KW rating as the breaker will limit this.
 

Dennis Alwon

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Chapel Hill, NC
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Retired Electrical Contractor
I think you are mixing two situations. Optional calculation is for service or feeder calculations not for the branch circuit.

The minimum circuit for a range branch circuit is 40 amps however you use Table 220.55 Note 4 to calculate the branch circuit needed. A 14.3kw range will only require a 40 amp circuit simply because the elements of the stove top and oven are thermostatically controlled so the load of 14.3kw will never be realized in the real world
 

rodma808

Member
Location
honolulu
I think you are mixing two situations. Optional calculation is for service or feeder calculations not for the branch circuit.

The minimum circuit for a range branch circuit is 40 amps however you use Table 220.55 Note 4 to calculate the branch circuit needed. A 14.3kw range will only require a 40 amp circuit simply because the elements of the stove top and oven are thermostatically controlled so the load of 14.3kw will never be realized in the real world


Dennis,

Thanks for your response.

I am not confusing branch circuits vs feeder. I am speaking strictly about the FEEDER only. (I restated my original question only because the response I received appeared to misunderstand my question).

1. For the NEC dwelling load calc, name plate data is to be used for the optional calculation.

2. If the 14.3KW (name plate) is never realized (as you say), then why do i need to use the 14.3KW for the calculation?

3. The load is also limited by the 40A breaker? So why use the 14.3KW in the NEC optional dwelling load calc?
 
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