Oven Electrical Question

[Walter R.]

I am replacing my built in oven/microwave combo with a separate thermal oven and a microwave. The oven will take 220 V, the Microwave is a plug-in (built-in) above the oven and requires 110V.

Can I extract 110 V for the MW from the 220 V junction box (line to 220V thermal oven )? The 220 V line has a 40 Amp Circuit- breaker.

This house is 25 years old. I cannot tell if 3 or 4 wires go from the main panel to the junction box.

[RBM]

No, you'll need to run a dedicated circuit for the microwave

[Toller]

25 years old is probably 3 wire. That makes the idea impossible, even if you were willing to put in a load center.

It would be a bad idea in any event.

[Doug Miller]

Possibly...

.. but you need to find that out first. With 3 wires, it's impossible to do it safely and legally (you need, but don't have, a neutral). With 4 wires, it's merely impractical.

Here's the problem you run into with four wires: the microwave almost certainly is intended to plug into a 15A (or maybe 20A) 120V circuit, but your existing wiring is likely 8-gauge. 120V receptacles aren't rated for wires that large, and cannot grip them securely, so you'll have to have 12- or

14-gauge wires going to the receptacle for the microwave -- but it's a Code violation to put anything smaller than 8-ga on the 40A circuit that you now have.

[Walter R.]

OK. Thanks. Back to the drawing board.

[Thomas Avery]

Your question indicates your lack of electrical knowledge. In lieu of a fire or possible fatal shock, CALL A LICENSED ELECTRICIAN!