Electric Range & Microwave Wiring


Old 09-06-08, 08:19 PM
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Electric Range & Microwave Wiring

I'm in a 20 yr old home w/ a combined range/microwave unit which we will be replacing with a separate range & microhood.

It sounds like it'd be best to run a dedicated 20A 120V circuit to the microwave. Agree?

The existing appliance is wired directly. Seems like good sense to install an outlet, but which type? Is there a 10-40R? (read on)

The existing wiring is 6 AWG w/ only 3 conductors (red (stripe), black & bare aluminum). The complete marking is:
The circuit is on 40A breaker (pair) -- seems like code is (has been) 50A?
The other thing that bothers me is the only label I can find on the existing range says 13.8 KW for 120/240!?! Wouldn't that be >57A?!? We've never tripped the 40A breaker in 15 years.
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Old 09-06-08, 09:51 PM
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The #6 is fine for 50A but you should protect it with a breaker of the size specified in the range manual. It may be that they say 40A. The wattage you refer to is an absolute total and under normal conditions you would never achieve that. Protect it with what the manual specifies and you will be fine.

BUT !!! By code you cannot use that 3 wire connection anymore. In the past they used the neutral as a ground (3 wire) but you now need to run 4 wire cable or 3 wire with ground back to the main panel. The connection to the stove and plug needs to be 4 conductor also. They sell 4 prong stove hook up plugs at Home Depot or Lowes. They also carry outlets

The microwave should be on it's own 12/2 20A circuit with a standard 120v outlet.
Old 09-07-08, 01:18 AM
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There is no 40A receptacle. 40 and 50A stoves use the same style plug. Which unfortunately must be 4-wire, all new appliances are that way. Run 6ga 3wire+ground, put in a 50A receptacle, and install whatever size breaker your new stove asks for.
BTW, if you have gas in your house at all, put a second outlet behind the stove on that new 120V circuit yer going to run for the microwave. If anyone ever puts in a gas stove, they'll need that outlet to power the controls. I forgot that once. :|

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