Range Amperage Question


Old 09-12-04, 09:23 PM
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Join Date: Jun 2004
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Range Amperage Question

Need a little help figuring up the amperage rating for a 240 volt, 12,500 watt electric range. I know its not as simple as wattage/volts but i can't recall the formula used to calculate it. I figure it should be 50 amps but would like some confirmation. My neighbor currently has said range on a 40 amp breaker with 8 guage wire, is there any real problem with that except for an underperforming range?
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Old 09-13-04, 05:44 AM
Join Date: Sep 2003
Location: Central New York State
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Yes, the formula is as simple as P=VI. However, in your case you need to refer to the manufacturers directions. Look at the plate on the range, or look at the original installation instructions, or go to the manufacturers web site to see what size wire and what size breaker are recommended.
Old 09-13-04, 05:47 AM
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Did the range come with any specified or recommended wire or breaker size? From the 12.5kW power rating on the range, I would use 6/3 cable and a 50A breaker. There are safety reasons not to undersize the wire--if you use a wire that is too small, it will heat up and possibly cause a fire.
Old 09-13-04, 06:55 PM
Join Date: Aug 2004
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To answer your question the Nec requires installation in accordance to manufacturer instructions. It also requires the miniumum branch circuit rating for ranges nameplate rated over 8750 watts to be 40 amps, requiring a minimum of 8 awg large appliance wire. The calculation you refer to is Table 220.19 of the Nec. Given your situation and the manufacturers instructions unavailable the calculation using table 220.19 taking into account deration factors would be 8000 watts + (8000watts * .05) or 8400 watts branch circuit load. This deration is the result of taking into considertion that you are not going to have every heating element on maximum heat. However the range in question is 12,500 watts so you must comply with NEC 210.19(c) of a minimum 40 amp branch circuit rating. The stove will not underperform as it is currently wired unless you try to heat the house with it.....Roger
Old 09-14-04, 08:53 PM
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Join Date: Jun 2004
Posts: 76
Thanks for everyone's input,. I'll recommend to him to upgrade the circuit to 50 amp 6 gauge, its only 20 or so feet and its a straight shot so it should be easy to handle.

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