# 240 Volt Oven Wiring



## antimoth (Aug 8, 2009)

So I'm remodelling a kitchen and I pulled out a 24" oven that runs on 240 VAC (and a 20A breaker) so I can replace the cabinet. When i disconnected the electricity, I noticed that the red/black wires in the outlet box were 10 gauge, but the white was only 14 gauge as was the green ground, I'm thinking the only current that goes thru the white would be digital clock and control as that's probably 110., 

The oven's been there for 20 years and always worked. Never tripped the breaker. Should I pull a heavier wire for white?


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## Frank4d (Sep 10, 2006)

The white wire is the neutral for the digital clock and oven light. 14 gauge is fine.


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## Drabdr (Nov 26, 2007)

Frank4d said:


> The white wire is the neutral for the digital clock and oven light. 14 gauge is fine.


Yep, agreed. :up:

National Electric Code allows smaller gauge wires for neutrals and grounds (in some instances).


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## Koot (Nov 25, 2007)

If the Black and Red wires are 10 gauge then the white (Neutral) wire is almost certainly 12 gauge, not 14 gauge. 20 years ago all sheathed cable (Romex) had a reduced gauge Neutral wire and Ground wire - reduced by one gauge size...except in the case of 14 gauge, which also had a 14 gauge Neutral and Ground wire. That said, your reduced gauge Neutral wire and Ground wire is perfectly okay. (It's not allowed by the NEC today, but it was years ago.) In your case, the Neutral wire will only be used for the return leg for the oven clock and lights. Nowadays all Neutral and Ground wires are the same gauge size as the main current carrying wires.

Further, 10 gauge wiring is good for 30 amperes. Since the circuit breaker protecting this circuit is rated at 20 amperes I think you may find that your Black and Red wires are probably 12 gauge (in lieu of 10 gauge) with a 14 gauge Neutral and Ground. If so, then the 12 gauge wiring is good for 20 amperes, which matches the circuit breaker. And the Neutral and Ground wires would be reduced size (14 gauge), which was standard many years ago.

(Note: If the wiring really is 10 gauge, as you stated, there is nothing wrong protecting the wiring with a 20 ampere circuit breaker. You always want the protection device (e.g. breaker, fuse, etc.) to be the weakest link, which it is. The circuit breaker is designed to trip at about 80% of its amperage rating after a couple of cycles [1/60th of a second] anyway.)


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## antimoth (Aug 8, 2009)

Thanks to all for the advice. I will have to size the thicker wires to see what they are for sure. Assumed it was 10 gauge The other two are definitely 14 though. All separate wires in conduit.


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## Koot (Nov 25, 2007)

antimoth said:


> Thanks to all for the advice. I will have to size the thicker wires to see what they are for sure. Assumed it was 10 gauge The other two are definitely 14 though. All separate wires in conduit.


It's highly unusual for a residential range (oven) to be fed with wire pulled in a conduit...unless the building is multi-purpose or some other type that requires conduit must be used. Or the house was remodeled and the electrician found it best to run a short length of conduit to feed wiring to the oven instead of pulling Romex. Since the wiring is in a conduit you may very well have 10 gauge wires for the Black and Red and [only] 14 gauge for the Neutral and Ground. If so, you're perfectly okay with the existing wiring for your oven. However, that would definitely not be allowed if the installation was being done new today.


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## antimoth (Aug 8, 2009)

I'm pretty sure I got red and black in 12 gauge, and green and white in 14 gauge. It's 1/2" conduit. Would be really hard to pull 10 gauge thru it.

However, the oven is rated 3.8kwatts at 240 volts, so it draws a peak of 15-16 amps, which allows this oven to run on a 20A circuit. 

In Illinois where I live, I believe romex is verboten. I've seen it used in new construction in New Jersey where they just staple it to the joists, but the last house I sold in Illinois got flagged at inspection because it used romex to power up some ceiling lights in a dropped ceiling.


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## Drabdr (Nov 26, 2007)

Koot is correct here. Basically, you want the breaker to protect the conductor (which it sounds like it is). 

To me, if it isn't broke, no need to fix it. If the wire is rated for the load, with proper overcurrent protection (for the conductor), and it's been working, I wouldn't worry about it.


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