Convert 3 wire 240v circuit to 4 wire?


Old 05-29-16, 09:27 AM
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Convert 3 wire 240v circuit to 4 wire?

I am building a medium sized oven to cure powder coated parts.
I have an old electric oven that had a full size oven and a secondary smaller oven.
I pulled the two 1500 watt elements and wiring harness from the smaller oven to use in my project.

The oven used a standard three wire plug with Black, Red, White. The white neutral wire is used by 110v components on the stove such as an electronic control board, power oven door lock, interior lights, etc. No components on the harness I pulled make use of the neutral wire but the wire is bonded to the chassis of the unit with a copper strap which as I understand it was typical for three wire setups but not with todays 4-wire.

I have a 4 wire 30amp outlet in my shop I installed years ago for my band saw which I would like to use to plug in my powder coating oven. I have not wired an AC plug to the oven yet but I assume that if I were using the three wire plug I would wire the neutral to the frame even though I am not using it elsewhere in the circuit.
To change the circuit to the newer 4-wire line what would I change? Would I leave the neutral disconnected and use the ground to chassis instead?

Below is the portion of the oven wiring diagram for the parts I am using. Black hot is on the left, red hot on the right and neutral on the outside right though it does not show connections in this portion of the diagram.

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Thanks in advance.
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Old 05-29-16, 12:28 PM
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If your current stove was wired for three wire connection... you would need to remove the jumper from the center stud, which is neutral, to ground.

If you are using a four wire cord then just connect the two hots and the neutral to the connection block and the green goes directly to the appliance frame.

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Old 05-29-16, 04:29 PM
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Are you making use of the oven itself or just pulling parts out of it install in your own enclosure?

If you are using heating elements and controllers only, you will not need neutral at all. Just connect ground to enclosure/chassis and use 2 hot wires.

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