Calculating breaker size for an electric range.

I'll bet you guys are sick of hearing about the cabin ;-)
Well, you see in this properly wired and grounded lake cabin, we have a
small galley kitchen. Accordingly we have downsized our appliances.
We plan to purchase a 24" /240VAC Electric Range with the following features:
Cooking Element 8" @ 2200 watts Cooking Element 6" @ 1200 watts Baking Element @ 2400 watts Broiler Element @ 2750 watts
I think I know, but I wanted to run it by the community...
To estimate the proper breaker/wire size wouldn't I take the total wattage and divide that by 240 Volts to get my amperage? In this case AMPS= 35.625 So, I would need at least a 40 AMP Breaker and #8 copper conductor.
Correct?
Se๑or Tarin
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40 Amps Breaker and conductors of 10 mm squared cross sectional area is fine for this situation.
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BigWallop wrote:

BigWallop May I suggest that you use caution when answering any question that involves north American electrical practice. Wire sizes here are given in American Wire Gage (AWG). There are regulatory limitations on the use of gages of 6, 4, & 2.5 mm squared. Even though that has no effect in the instant case it is worth while to remember that practices that are acceptable in Europe are often forbidden or unavailable in North America and vice versa. Providing advice that is not expressed in the language and terminology of the area in which the OP resides is often unhelpful or worse still confusing. -- Tom H
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wattage
fine
Point taken and heeded Tom H. Will convert Euro-Metric to AWG in any other replies I make from now on.
I realise now that our UK 10mm^2 csa' is closer to #7 AWG gauge, which is confusing to someone reading the reply I made further up this thread.
Thanks for pointing it out.
(BigWallop smacks own wrists for being silly)
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wrote:

40a is probably right, based on the plug you usually get on one of these but the amps will be 25.4666 since the broiler and bake element won't be on togerther (take the larger only)

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Standard stove 40 amps Number 8 or larger 50 amp cordset and receptacle

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Read the pamplet that comes with range. 40 amps should be good unless the manufacturer reccomends something else
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wrote:

Might be hard to find a 40 amp cordset with separate ground and neutral (4 wire) which the code now requires after years of permiting (3 wire) installations whereas 50 amp cordsets are readily available (and pretty much the standard for 240V. electric ranges).
I would play it safe and stick with with the 50 Amp standard unless indeed the range instructions recommend otherwise.
Beachcomber
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cabin, we have a

appliances.
following
total wattage

case AMPS= 35.625

conductor.
No. you size for diversity of use.. will you be broiling and baking at the same time? No. so subtract out 2500 watts right away. You will be better off and safer with a 30 amp breaker. the #8 copper wire is fine.
Phil Scott

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Phil Scott wrote:

Many ovens use both elements to heat up quicker, then drop the broiler when up to temp. #8 wire is OK, a 40A breaker may be needed. Check the manual, or the controls to see if it works this way.
--
Virg Wall

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Phil Scott wrote:

Can't do that. From NEC 210-19 (c): (c) 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.
The sizing you refer to comes into play not for the conductors of the circuit supplying the appliance, but in an overall load computation. And in this case it would allow computing the load that the range would present at 80% of its total. The NEC specifies 80% of the total for ranges under 8 3/4 KW. This one is 8550, so you can subtract no more than 1710. But this is NOT applicable to determining the size of the conductors serving the range. 210-19 (c) states that you must use the maximum load, not 80 percent of it.

Can't use a 30 amp breaker for this per the above, and per 210-23. It states that the rating of any single piece of equipment that is cord and plug connected to a 30 amp circuit must be no more than 80% of the circuit rating. That means the range's rating would have to be 5760 or less. That won't work, even if you subtract the 2500 watts.
#8 copper is correct - but he must use a 40 amp breaker.
Ed

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diversity? what is this some sort of german condo oven
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Re: Calculating breaker size for an electric range. Group: alt.engineering.electrical Date: Wed, Apr 6, 2005, 6:07am From: snipped-for-privacy@look.ca (PCK)
No.   you size for diversity of use.. will you be broiling and baking at the same time? No. so subtract out 2500 watts right away.   You will be better off and safer with a 30 amp breaker. the #8 copper wire is fine. Phil Scott Se๑or Tarin diversity? what is this some sort of german condo oven
I don't know what it is any more }:-) ((((( A Cabin that has an underground High Tech Dwelling with an Inter-Planetary Communications System an all:-)))))
Seriously: It seems the best thing to do is follow the installation instructions to the letter ];) or is it a Thrift Store item ? XXXXXXX did i read the other threads wrong ????? if it says wire it up for 30 amps why tap it to 40 or 50A circuit protection? XXXXXXXXX
you're withholding something ~$~
ฎoy
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If it requires a 40 AMP Breaker, and I'm safer with 30 AMPs, would I be twice as safe with a 15 AMP Breaker????
Just kidding.
But seriously, wouldn't a 30 AMP breaker possibly cause a lot of nuisance tripping?

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tarin wrote:

It could. But the point is moot. Wire it for 40 amps, put a 40 amp breaker in there and you're done. If you put a 30 amp breaker in there, you violate article 210-23 (b). It is best to use and wire electrical equipment per manufacturer's instructions and the electrical code.
By the way: Undersizing a breaker could lead to welded contacts, where the breaker can't trip. Definitely *not* safer than a properly sized breaker.
Ed

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While true *in theory*, most breakers of the sort used in residential service panels are rated for 10kA interrupting. Tripping due to slight overload (as opposed to a bolted fault), is trivial to them. A lot of nuisance tripping due to slight overload just wears out the mechanism, but won't 'weld'.
daestrom
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wrote:
|> tarin wrote: |> |>>If it requires a 40 AMP Breaker, and I'm safer with 30 AMPs, would I be |>>twice as safe with a 15 AMP Breaker???? |>> |>>Just kidding. |>> |>>But seriously, wouldn't a 30 AMP breaker possibly cause a lot of nuisance |>>tripping? |>> |> It could. But the point is moot. Wire it for 40 amps, put |> a 40 amp breaker in there and you're done. If you put |> a 30 amp breaker in there, you violate article 210-23 (b). |> It is best to use and wire electrical equipment per manufacturer's |> instructions and the electrical code. |> |> By the way: |> Undersizing a breaker could lead to welded contacts, where |> the breaker can't trip. Definitely *not* safer than a properly |> sized breaker. |> | | While true *in theory*, most breakers of the sort used in residential | service panels are rated for 10kA interrupting. Tripping due to slight | overload (as opposed to a bolted fault), is trivial to them. A lot of | nuisance tripping due to slight overload just wears out the mechanism, but | won't 'weld'.
I have done "experiments" before. I managed to weld the contacts together (or at least one of them) of a 30 amp double pole switch. I don't do "experiments" like that anymore. Maybe some day I'll resume that hobby in a more controlled and safer environment.
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daestrom wrote:

It is my understanding that the current interrupting capability is a one time rating. After the first interrupt, that 10kA (or whatever) rating no longer applies. With nuisance tripping, the contacts *will* arc, and the interrupting capability *will* decrease.
Then there's FPE. Sorry, it ain't just theory. I don't know if it is welding, per se, but the breakers fail where they won't open the circuit, which has the same effect. See http://www.inspect-ny.com/fpe/CPSCsummary.htm
Ed

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The NEC, and it does require a 40 AMP breaker and #8 Copper conductor. That being said, can I use a #6 conductor with the 40 AMP breaker? I have some extra and it would save me a little bit of money if I didn't have to run out and buy #8.

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wrote:

I'm sure you can do more than the min, per code, but I would highly recommend you don't mix conductor sizes. Example, if you start from teh panel using 6awg, and along the way use 8awg, it's possible later a person can see the 6awg in the panel and think a 55 amp breaker is ok. See the problem? If you still want to mix, You can label that circuit as 40amp only, just follow the example in the NEC.
hth,
tom

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