Oven 3 wire question

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Stevenfyeager

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United States, Indiana
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electrical contractor
Customers new double oven is 4 wire. Existing branch circuit is 3 wire. No problem, I thought, we run into this all the time. So I read the installation notes and it says “connect the oven ground and oven neutral together to the branch circuit neutral (white)”. But of course we don’t have a neutral, only a ground. I try calling GE and they say we can’t call technicians anymore but she hesitates and gives me a tech number. He says he can’t help me as he reads the instructions. Do I chance voiding warranty and connect them to the ground? Is the instruction worded wrong? I asked these questions to the tech, he was not much help.
 
"Existing branch circuit is 3 wire." means 3 wires, each with insulation and they will be (if in NM) red, black and white. The bare ground wire is missing in the case of older appliance "3 wire" setups.
 
Stevenfyeager said:
It is bare
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See NEC 250.140 Exception. A bare grounded conductor (neutral) is allowed for bonding a range frame if, per part (3) "the grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment."

Cheers, Wayne
 
Stevenfyeager said:
I thought neutrals had to be insulated
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This is the exception that proves the rule. When a wiring method has both a neutral and an EGC, the neutral needs to be insulated to avoid inadvertent neutral/EGC connection. But for an ungrounded (no EGC), non-metallic wiring method, the neutral can be bare. Something you only run across in old existing installations, as any new circuits would have to have a grounding conductor.

Cheers, Wayne
 
Stevenfyeager said:
Customers new double oven is 4 wire. Existing branch circuit is 3 wire. No problem, I thought, we run into this all the time. So I read the installation notes and it says “connect the oven ground and oven neutral together to the branch circuit neutral (white)”. But of course we don’t have a neutral, only a ground. I try calling GE and they say we can’t call technicians anymore but she hesitates and gives me a tech number. He says he can’t help me as he reads the instructions. Do I chance voiding warranty and connect them to the ground? Is the instruction worded wrong? I asked these questions to the tech, he was not much help.
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Check the manufacturers spec's.
I believe you may need to install a 4 wire.
Some say 3 or 4 wire is okay and some don't.
 
Knuckle Dragger said:
Check the manufacturers spec's.
I believe you may need to install a 4 wire.
Some say 3 or 4 wire is okay and some don't.
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I've installed tons of ranges & ovens covering most brands. All of them have instructions for 3 and 4-wire. Never saw one that said you must run a 4-wire circuit if you only have a 3 wire.
 
Having a 6/2 8/2 or 10/2 NM with ground to a "120/240" 3-wire range, oven , cooktop or dryer was never permitted by code going all the way back, and violates the 250.140 exception item (3). Thats how my dryer circuit was wired in my first house. 10-50 receptacle on 10/2 with ground romex.
 
Almost every range or oven I've seen in the last 20 years comes wih the EGC bonded to the neutral inside the rear wiring compartment . When HO's buy the appliance the store they buy it in will supply or sell them a power cord. If you have a 4-wire feed you'll need to separate that EGC-N strap. Otherwise, for a 3-wire connection you'll have to do as Wayne mentioned in post # 6. Make sure it was run in SE cable as well.
 
the existing circuit is not SEU. It is 8-2 romex. The 3 wire instructions: (I tried a photo but) "Connect the oven ground conductor along with the neutral (white) lead to the branch circuit neutral (white or gray in color), using a wire nut." Is it ok to use the bare ground in the 8-2 ?
 
Stevenfyeager said:
the existing circuit is not SEU. It is 8-2 romex. The 3 wire instructions: (I tried a photo but) "Connect the oven ground conductor along with the neutral (white) lead to the branch circuit neutral (white or gray in color), using a wire nut." Is it ok to use the bare ground in the 8-2 ?
Click to expand...
Nope.
 
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