How to convert 40 amp breaker to 20 amp breaker

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Old 07-19-16, 07:15 AM
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How to convert 40 amp breaker to 20 amp breaker

I am replacing a electric cook top with a gas cook top and currently have a 40 amp circuit with one black wire, one red wire and a unshielded ground wire connected to a 40 amp breaker in my breaker box. My question is how to I convert this to a 20 amp circuit to supply my new gas cook top? Thanks!
 
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Old 07-19-16, 09:59 AM
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If by unshielded you mean bare and you mean a 120 volt 29 amp circuit you can't. You need a white or gray wire for that. The red is to small to be remarked as a neutral and the bare can not be use as a neutral. Don't you have a nearby counter top receptacle you van plug it into?
 
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Old 07-19-16, 03:56 PM
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Thanks so much for the response! just so I know way is the red wire too small to be re used as the neutral? it is the same size as the black wire? I'm just curious... your the pro! Thanks
Oh and btw the red and black wires are stranded.
 
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Old 07-19-16, 04:04 PM
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No, the red is too small to be re-identified as a neutral. Only wires larger than #6 can be re-identified as a neutral.

This is might be allowed by some inspectors if there is no other way to get a proper cable over there. As Ray asked, do you have another location you can get 120 volts? Do you have an unfinished basement or crawlspace?
 
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Old 07-19-16, 05:17 PM
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way is the red wire too small to be re used as the neutral?
It is illegal because someone may make a mistake in the future. It is legal for #6 or bigger because they only come in black.

Personally, if it is not going to be inspected and you don't plan on selling your house anytime soon, I probably will choose to use one of the wire as neutral.
Just remember it is at your own risk.
 
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Old 07-20-16, 05:25 AM
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Assuming the red wire was properly sized for 240 vac at 40A, why can't it be used as a neutral for a fused circuit at 120 vac at 20A? Is there a problem from a wiring rating consideration or just the insulation color? Can't it be marked or pig-tailed white at each end? Isn't this done for when a switch is wired to a light where the power comes into the light first?
 
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Old 07-20-16, 05:41 AM
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The white in a cable can be marked as a hot. The same allowance does not exist to mark a hot as a neutral.
 
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Old 07-20-16, 08:08 AM
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Thanks!

Thanks for all on the replies! I understand now.
I actually started tracing the wire and found a box in the wall that has 2 - 10 gauge cables in it that both contain red, black,white and copper ground wires. So I should be able to replace the 40 amp breaker with a 20 amp and use the black white and ground (cap off the red wire) for my 20 amp circuit.Will this work?
 
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Old 07-20-16, 10:08 AM
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able to replace the 40 amp breaker with a 20 amp and use the black white and ground (cap off the red wire) for my 20 amp circuit.Will this work?
Yes, that will work. You will need to buy a filler for the blank space left in the breaker panel front when you switch to a single pole breaker. The receptacle will need to be GFCI protected or a GFCI receptacle.
 
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Old 07-20-16, 10:27 AM
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Thanks Again!

Thanks to everyone that replied you all have been very helpful and educated me with a small amount of electrician knowledge. Thanks for your expert advice.
 
 

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