How to override the need for a neutral wire for an oven hookup

Question

I have had my kitchen remodeled. I have new cabinets and a stone countertop. When it came to hooking up the oven, I was told I needed a neutral wire for the oven to work after the cabinets and countertop had been installed. My house was built in 1953, so there was no original neutral installed. The cabinet is on island. How can I make the oven usable without destroying the new cabinet and countertop. If a transformer is used will that solve the problem? I live in the United States.

Answer 1

Where the existing wire is "/2+ground" (black white bare) cable, It was never legal to wire a 240V range or oven which needs neutral. But many bad installers did it. Ranges have no need for 120V except for the oven light. At the time, the concept was "every house has a bunch of 120V incandescent bulbs fit for oven lights". Today, that concept is dead.

Where legacy /2+ground exists, the only option is to replace the cable run, or obtain a range/oven that does not require neutral.

With SEU or "/3 no ground" there are options.

Option 1: NEC 110.3(B) Follow Instructions.

Oven circuits included:

• 2 hots and a neutral up until 1966
• Either way until 1996
• 2 hots, neutral and ground after 1996

Most likely, you are looking at SEU* type cable, which is 2 insulated hot wires and a bare neutral. Really. I can understand confusing it for ground, but it's neutral. *It can be used as a ground but doesn't have to be.

Now, NEC 110.3(B) requires you install equipment according to labeling and instructions (implying: "Read them"). Those instructions may tell you how to connect your range to a 3-wire "hot-hot-neutral" connection. If so, you can simply do that.

However, be warned: 3-wire connections have a serious problem, and that's why they were outlawed in 1996. They've killed a lot of kids. When the neutral wire loses connection (a routine failure), it energizes the chassis of the range. I'm absolutely not a fan.

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* "Service Entrance, Un-armored" is designed for the first bit of wiring between the weatherhead and the main breaker. This comes from the power company and does not have a ground. Ground is established at the main breaker, via ground rods.

Option 2: Install a GFCI breaker and don't connect ground

The standard instructions tell you on 3-wire connections to wire the oven chassis to neutral. I hate that. Instead, you can install a GFCI breaker at the panel, and then, follow the 4-wire connection instructions, which tell you do not wire the oven chassis to neutral. In this configuration you connect ground to nothing. (that's important for the GFCI to protect you).

Now, if the neutral wire gets loose, nothing happens except the oven light stops working. If a hot wire contacts chassis, the chassis becomes energized and that's fine - because as soon as someone touches it and starts to be shocked, the GFCI instantly trips.

Do not connect oven ground to neutral in this instance.

If the range connects via socket and plug, use 4-prong socket and plug and label it "GFCI Protected / No Equipment Ground". These labels come with every GFCI. Wire the stove according to the instructions for a 4-prong plug (separate neutral from ground).

Option 3: Retrofit ground.

With great care to keep neutral and ground separate, a #10 ground wire can be retrofit via any achievable route from the range (4-prong socket if used) to any of the following:

• The panel, obviously
• Any place with a #10 ground going back to the panel (e.g. water heater or A/C)
• Any place with non-flex metal conduit back to the panel
• the bare copper Grounding Electrode System wires from panel to ground rods or water pipe.
• Do not ground to gas or plumbing pipes.

Now you have 4 wires honestly, and use a 4-wire grounded connection in the normal way.

Option 4: Hack the range to not use neutral

Generally, the loads on a range that care about 120V are quite small. They could be supplied by a transformer of practical size. Any UR-Recognized transformer with 240V and a center tap should suffice. It can have a secondary that just wouldn't be used. Of course that would violate NEC 110.2 and 110.3(B), however not that much if your manufacturer makes a version of this range for the Philippines. That's exactly what they do with those ranges, except they wire it for a 240V oven light.