OT question for the electricians

I am changing out our single wall oven for a double convection wall oven. My current service is 30 amps and the specs for the new unit call for 40 amps. The run from my panel to the plug is 38'. Is there any reason to just put in a 50 amp service for a 40 amp oven or will a 40 amp do? I am not sure about voltage loss over the distance or any other factors I don't know about.

Jason

#10 wire for 40' will work great for 40amps.

#10 wire is good for 30amps
#8 wire is good for 40amps
And normally you would upsize the wire for anything over 100' for derating purposes
You install #10 wire on a 40amp breaker, you are asking for trouble and your place burns down, your insurance company will not cover you....and yes they will discover it.

#8 wire. ITs actually good for 45 amps. no need to upsize unless its over 12kw.
50 amp breaker puts you into a wider frame size in most cases. 40's are still narrow (usually)
regular range receptacles are already good up to 50 amps.
38' is not even close to a long enough run to worry about voltage drop. (only real issue is how fast 8/3 can drain your pockets when buying a lot of it)

He's only running 38 ft of wire.

Curt wrote:He's only running 38 ft of wire.

Doesn't matter if it's 2' of wire

jjmstang wrote:
You install #10 wire on a 40amp breaker, you are asking for trouble and your place burns down, your insurance company will not cover you....and yes they will discover it.

There is not an exclusion in any policy I have ever seen that would not cover it. However, I am not an electrician, I just played one on TV. I am however a well compensated Insurance adjuster.

I usually stay out of electricaL questions because they almost always lead to pissing matches however, I've been in the trade for 18 years so, I feel fairly comfortable talking about the subject.

The largest breaker you can land a #10 gauge wire on is 30A for a branch circuit. There are some instances in motor circuits where the Code will allow you to put 14 gauge wire on a 70A breaker but, not for a branch circuit in a dwelling. The largest breaker you can land a #8 gauge wire on is a 40A...they don't make a 45A breaker.

Jason, more than likey you will need to install a 40A circuit, with #8 wire. It will also probably need to be a 4-conductor cable (8/3 with ground) because these appliances are rated at 120/240V...meaning they need a neutral conductor, usually for a clock or timer. For many year, 3-wire circuits were used for this type of application, until the NFPA realized that there was unbalanced current being sent back on the bare grounding conductor, again, usually from the clock or timer.

I would recommened installing a 40A circuit for it and not try to use the existing 30A...it may hold it but, you are technically only allowed to run a breaker at 80% of its' capacity by Code....meaning that if the new unit pulls more than 24 amps, to be Code compliant, it needs to be on a 40A breaker anyway. I would highly recommend having a licensed electrician evaluate the situation if you are unsure of any part of it.

Jeff

I appreciate all the answers. I have no intention of using the 30 amp stuff I planned on upsizing to 8 gauge and 40 amp breaker. I was more curious if it advisable to just put in a 50 amp service to make sure there was enough power for the 40 amp device. A little extra cushion sorta thing...

no point in going 50 amp. you (or your wife) will NEVER have all the elements on at the same time.
The question i have is....Do you have a separate cook top to go with this or is it a free standing unit?
you would just need to be careful with tap conductors if that were the case.

Diggindeeper wrote:no point in going 50 amp. you (or your wife) will NEVER have all the elements on at the same time.
The question i have is....Do you have a separate cook top to go with this or is it a free standing unit?
you would just need to be careful with tap conductors if that were the case.

I don't know we can cook the shit out of some turkeys around here. LOL. I am looking forward to having the double oven. We are weird and actually eat dinner as a family every night, cook our own meals for holidays, Lisa bakes non stop etc.