240 Convection Range

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Old 03-18-15, 04:56 PM
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240 Convection Range

Customer purchased a new range. I don't think the breaker can handle it.

Breaker = 40amp double pole

Range = 13.8 kw

Am I correct - 57.5 amps total draw. This seems ridiculous.

Edit: I may as well ask now. What's the highest KW rating she can install on a 40amp breaker.
 

Last edited by Handyone; 03-18-15 at 05:20 PM.
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Old 03-18-15, 05:58 PM
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Am I correct - 57.5 amps total draw.
Correct !

40x240= 9600 watts. The range is not considered a continuous load.

We had this same discussion a month or two ago with a member. I believe it was Sears unit and their installation instructions said something like 40A and to check the rating plate.
 
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Old 03-18-15, 06:07 PM
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Convection Range

Table 220.55 shows a demand of 8 KW for a range not exceeding 12KW. If the range exceeds 12KW then you have to add 5% to the demad for every KW or major fraction it is over 12KW. 13.8 would be 1.8KW over so add 10% to the 8KW for 8.8KW/240=36.66 Amps. 40Amp breaker would meet code.
 
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Old 03-18-15, 06:15 PM
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According to code you are correct. What happens when the homeowner turns everything on and it draws well over 40A ?

We had the same discussion previously. I actually obtained the element wattages and did a computation of all the elements that could be on at one time and it came to well over the code required breaker size.
 
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Old 03-18-15, 06:23 PM
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Convection Range

That would be when we get all thoses service calls around Thanksgiving. Not sure why the code allows the deration for a range but not a wall mount oven as in Table note-4. I assume they figured there was less demand with a range for some reason. If you install a wall-mount oven and a cook top you have to go by Note-4 so I would think a stove is about the same thing. Like you I am in favor of using the name-plate, at least on my kitchen.
 
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Old 03-18-15, 07:43 PM
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Table 220.55 shows a demand of 8 KW for a range not exceeding 12KW. If the range exceeds 12KW then you have to add 5% to the demad for every KW or major fraction it is over 12KW. 13.8 would be 1.8KW over so add 10% to the 8KW for 8.8KW/240=36.66 Amps. 40Amp breaker would meet code
I remember that post PJ. I was involved a little and I was astonished an oven would require that much power. Well, this one does.
Convection fan with element, oven element, warming drawer, burners (elements), you name it.

I need to give her an answer by tomorrow:

Due to deration, can I hook this oven up and warn her to seek an electrician ASAP?
Or should I refuse to hook it up? I was supposed to install a surface mount 4 wire receptacle and four wire cable to oven.

"oven" means Range. Slide in Convection.
 

Last edited by Handyone; 03-18-15 at 07:55 PM. Reason: Slide in Range, Kenmore Elite
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Old 03-19-15, 06:32 AM
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I would just use the breaker recommended by the manufacturer. I have rarely seen a need for more than a 40 amp breaker. This was just covered in Code Question of the Day earlier this week.

The demand load for a single range is 8kW from Column C in Table 220.55. For household ranges 8 3/4 kW or more the minimum branch circuit rating is 40 amperes as stated in 210.19(A)(3). I agree with your math and the current measurement approximately confirmed the value to be 47 amperes. But that would probably only occur if the range was used as a space heater when the furnace failed. The oven elements typically cycle on and off to maintain the temperature setting and the cooktop elements would not all likely be on the highest setting, even during holidays or family gatherings, unless we wanted everything burnt.
Code Question
 
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Old 03-19-15, 06:57 AM
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Thanks Joe,
My plan is to hook it up today. I talked to her and advised she seek the advice of a professional electrician, but can use it in the mean time.

I would normally advise to get a different range, but any convection range will probably be around the same kW rating.

Thanks for the code question of the day. I agree that the chances of this range running at full capacity at any given time are very slim.
 
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Old 03-19-15, 07:01 AM
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Just an aside, Brian, she does know that convection cooktops can only be used with utensils containing iron, right? I had to take one out of a house for a client who swore it was broken, as she cooked exclusively in aluminum and corning ware. She opted for a standard stovetop instead.
 
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Old 03-19-15, 07:40 AM
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Chandler,
In your case, it sounds like it was an Induction Cook Top. Ferrous metal pans with flat bottom must be used.

This is different than convection cooking, which has heated fans in the oven cavity.

It's a great way to cook meat, poultry, and breads, restaurant quality!! Now I'm hungry
 
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Old 03-19-15, 10:15 AM
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Yeah, by the time I got breakfast cooked, I realized i misused the data and should have had the brain in gear before I responded. Yeah, Induction. Neat devices, cold to the touch, and immediately hot. When I realized it, I was putting my biscuits in a "convection" oven. DUH!!

My focus was on convection "RANGE". Nothing on the range top is convection, is it?? Just wondering.
 
 

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