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We were removing the in-wall oven from my in-laws' old house (which we rent) to replace it next weekend. The wall oven and cook top were fed from the same supply. In the junction box the cook top ground wire was connected to the neutral wire from the supply wire. The cook top only had the hots (black and red) along with a bare ground wire. So it was wired black to black, red to red, and ground to neutral. Why would someone do this?

It seems this is a 220V cook top (based on what I have read). This isn't something my in-laws would have done. They weren't DIYers. This would have been by the kitchen showroom that they had install their remodeled kitchen 25 or 30 years ago (I think).

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Many years ago, electrical was done without ground wires.

Range/ovens need 240V for all the stuff that makes heat, and 120V for the oven light (so you can use readily available bulbs). Because of this, ranges were supplied 120/240V hot-hot-neutral.

When the grounding "fad" took off, the NFPA wanted to mandate 4-wire range and dryer connections: hot-hot-neutral-ground. However, the appliance industry was appalled at the idea that people would have to upgrade in-wall wiring the next time they bought an appliance. It would crush appliance sales! So they pressured for a compromise, where if ground is absent, ranges and dryers could bootleg ground off the neutral wire, so the chassis is 'grounded' to neutral.

It helped their case that most 3-wire connections go back to the main service panel, where neutral and ground are bonded. The failure of the neutral wire would have the effect of electrifying the chassis, but that was reasoned to be "a risk worth taking" since these connections are rarely disturbed.

Even today, all ranges/ovens and dryers can be connected in 3-wire or 4-wire modes, with neutral internally jumpered to ground in 3-wire mode. It's not a good practice.


It was allowed to do this with /2+ground UF cable, which has a bunch of ground wire strands orbiting the conductors. These are bunched up and used as the neutral. Some thought they could do the same with NM cable (nope). Of course some installations have /3-no-ground cable, where the neutral wire is actually white.

In an installation with /2 UF or NM cable, you can redesignate the bare neutral to be ground. Otherwise you can retrofit a ground wire. You cannot retrofit neutral wires.


Now you know the history of 3-wire range connections, you can see why they attached ground to the neutral wire: appliance shop installers think of them as interchangeable, and are trained to use whichever. Installers are certainly not electricians.

  • Just to be clear the supply wire from the breaker box has a red (hot), black (hot), white (neutral), and green (ground). The stove has black (hot), red (hot), and ground. I just don't understand why they wouldn't have wired the ground to ground. From what I read that would be correct and the neutral from the breaker box would just get terminated in the junction box with a wire nut and tap. I think we are going to replace the cook top with a newer one, so I will have instructions, which aren't available for the old cook top. – Hott Oct 28 '18 at 21:58
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    You can't do anything at all on a house you rent. Even if the landlord gave you permisson, very likely your state or town has a law requiring commercial work be done by a licensed electrician. Rental property counts as commercial. I would move it over to ground on sight because there is a big safety issue and I yell a lot about it... but yes, unless something breaks the neutral wire this week, there's little risk. – Harper - Reinstate Monica Oct 28 '18 at 22:15
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    My wife and I are the landlords. I've always done the work even at the request of the city home inspector. It was my understand you are allowed to work on you own property. I know I have gotten multiple electrical permits to do work on my house.. – Hott Oct 28 '18 at 22:17
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    My post may have been confusing. My in laws are deceased. My wife and I own the house now. I just usually refer to it as their house. Sorry. – Hott Oct 28 '18 at 22:21
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    Oh, well that's different then. You can work on your own property if you are occupying it, or (perhaps) if it's vacant and under renovation. Of course all this varies by jurisdiction, and if your permit issuing authority is accurately informed and A-OK with it, that's the last word on the subject. – Harper - Reinstate Monica Oct 28 '18 at 22:34

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