If the neutral is not needed on a 2 pole 240v AC circuit to what should it be connected? My new oven has a black, red, ground, and a white wire. The wire from the circuit breaker has the same 4 wires. It is my understanding the 2 hots, red and black on a 240v 2 pole AC circuit don't need a neutral as the circuit alternates and performs what the neutral would normally do for a single pole circuit. The oven's installation info simply states "do not fuse neutral (white wire)" whatever that means is beyond me. So to what should the white wire connect?
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It'll help if you post the oven model number (link to the instruction book PDF if you have it), but this is a fairly common hookup and I think I know what the answer will be. Just need to double check the instructions.– Harper - Reinstate MonicaCommented Jul 29, 2018 at 21:13
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manualslib.com/manual/745055/…– continuallyfrustratedCommented Jul 29, 2018 at 21:20
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If your oven has a white neutral, you must connect it. Your understanding of the current flows in ovens and ranges is not in general correct. Some of these ranges and ovens (maybe all or the vast preponderance) use 240 V for the main heating elements, but 120 V for controls and maybe for even smaller heating elements. Hence, a white neutral must be connected. The admonition to not fuse the neutral does not mean a neutral is not needed. The neutral is connected to the neutral bar in the panel and is not fused there. The reason to not fuse the neutral is to avoid a loss of neutral.– Jim StewartCommented Jul 29, 2018 at 22:31
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Don’t forget the light bulb– TysonCommented Jul 29, 2018 at 22:36
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1A few other countries do "fuse" (read: breaker) neutrals. It's rare but perfectly allowed to do it in the US; it just requires a 3-phase panel and in this case a 3-pole breaker since common trip is mandatory. The oven's instructions are telling you even though it's allowed in the US, you can't with this oven. Yes, instructions can be more restrictive than Code (110.3b).– Harper - Reinstate MonicaCommented Jul 30, 2018 at 0:19
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2 Answers
If your oven has a white neutral on its connection block, you must connect it. Follow the instructions. Some of these ranges and ovens (maybe all or the vast preponderance) use 240 V for the main heating elements, but 120 V for controls, lights, and maybe even for smaller heating elements. Hence, a white neutral must be connected.
The admonition to not fuse the neutral does not mean a neutral is not needed. The neutral is connected to the neutral bar in the panel and is not fused there. The reason to not fuse the neutral is to never have a loss of the neutral without the loss of both hots. Loss of neutral can lead to the neutral becoming hot (shock hazard) and could lead to loss of control of the oven.
answered Jul 29, 2018 at 23:18
If your oven only had a black, red, and green with no white neutral to connect to the house wiring, you would simply cap off the white unused neutral so it is safe and tucked away.
But in your case the oven does have a neutral and thus it must be connected to the white neutral.
