Free standing range/oven

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1793

1793

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Location
Louisville, Kentucky
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Inspector
I have a question about a free standing electric range/oven. Trying to calculate the appropriate wire and breaker size for this unit in a remodel. The nameplate reads 3 wire 120/240 14.1kW.

At 100% 14,100 / 240 = 58.75 This seems high to me.

I was looking over the Demand Factor table in 220.55 and I?m confused on which Demand Factor Column to use. If I use Column C, am I reading correctly -- at 8% + 10%, for the additional 2.1kW above the 12kW as in note 1.?

Any clarification will be greatly appreciated.

Norb
 
Re: Free standing range/oven

Actually, its Note 4, but in the end you will use Note 1.

Column C states 1 appliance to be calculated at 8 kW. However, as Note 1 indicates, 5% must be added for each kW over 12 kW.

So, 8 + 10% = 8.8 kW / 240 V = 36.67 A

40A circuit breaker, #8 branch circuit conductors.
 
Re: Free standing range/oven

The 2nd & 3rd columns in table 220.19 are percentages - 80%, 75%, 65% etc...
The 4th column is kilowatts (1000s), such as 8000, 11000, etc...

your situation, you have 14.1-12 = 2.1 x 5%

2.1 x .05 = 0.105%

0.105% x 8kW = .84kW

8kW + 0.84kW = 8.84kW

So you use 8.84kW for your situation.

8840/240 = 36.83 amps
310.16 - you will need 8 AWG (based on the 75 degree C column)
 
Re: Free standing range/oven

You guys shouldn't be drinking that kind of punch at this time of day. :D
 
Re: Free standing range/oven

I know this may seem simple to others but I'm having a hard time wrapping my head around this. I have always just done as I was told and now I'm forced to tell others.
Do we always apply a Demand Factor for appliances, ranges, ovens and cook tops?

I was looking over some planes for a job and the information supplied with the Double Oven is:

Amp Rating @ 240V = 40
KW Rating @ 240V = 7.2

Any explanation of when to apply, or not, a Demand Factor will be most welcomed.

Norb
 
Re: Free standing range/oven

There is a real easy explanation of this that can be found in 210.19. As a contractor this explanation is where I make a profit instead of wages.

210.19 (A) (3) Household Ranges and Cooking Appliances. Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served. For ranges of 8? kW or more rating, the minimum branch-circuit rating shall be 40 amperes.
Click to expand...
Now look at Table 210.21(B)(3) and we find that I can install a 50 amp receptacle on this 40 amp circuit. Range is wired, money is in my pocket.
:)

[ October 17, 2005, 09:08 AM: Message edited by: jwelectric ]
 
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