NEC Load Calculations & Branch Circuits 3

Question 1

For a single household electric range rated 12 kW, what is the demand load per NEC Table 220.55, Column C?

Accepted Answer

8 kW

Answer

Column C lists 8 kW as the demand load for one range not exceeding 12 kW.

Question 2

What demand factor may be applied to four or more fastened-in-place appliances (other than range, dryer, space-heating, A/C) in a dwelling?

Accepted Answer

75%

Answer

NEC 220.53 permits a 75% demand factor when four or more such appliances are on the same feeder.

Question 3

What minimum VA must be included for a household electric clothes dryer when none is specified, per NEC 220.54?

Accepted Answer

5000 VA

Answer

NEC 220.54 requires a minimum of 5000 VA or the nameplate rating, whichever is larger.

Question 4

When sizing a feeder for fixed electric space heating, what demand factor is generally applied to the heating load?

Accepted Answer

100%

Answer

Fixed electric space heating is calculated at 100% of the total connected load per NEC 220.51.

Question 5

In the standard method, when may the air-conditioning load be omitted from the service calculation?

Accepted Answer

When smaller than the heating load

Answer

NEC 220.60 allows omitting the smaller of two non-coincident loads, so A/C is dropped if it is less than the heating load.

NEC Practice Test