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Old 03-21-2007, 10:02 PM   #1
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wiring a microwave


4 years ago, I put a microwave in place of my hood fan light above my stove. I did not have a dedicated line, but there are not many other used outlets on the same wire run. I have tripped the circuit breaker 8 or 9 times in the 4 years.

Is this illeagel?
What problems could happen?
How many amps does a 100 watt microwave use?

What I am wondering is my countertop microwave was 900 watts and did not have a dedicated line, why would an over the range microwave need one?

My microwave died and I am replacing it.


Last edited by Jack Hass; 03-22-2007 at 08:01 AM.
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Old 03-22-2007, 04:51 PM   #2
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wiring a microwave


Hey there

Quite simply I=P/E therefore I=100/120 = .83 of an A

Now i figured that out there is no way your microwave is only a 100W. It would take forever to cook your food, Maybe 1000W so that would be 8.3A.

The ones I have seen are usually higher. I would deftinely put that on its own circuit, especially if it is causeing your breaker to trip 2 times a year.

Not sure of code rule for your situation but i know our canadian code says that if a cabinet is made for the microwave that it needs it own circuit.

Hope this helps

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Old 03-22-2007, 05:39 PM   #3
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wiring a microwave


I believe another code is you cannot have a receptacle in a cabinet with doors?
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Old 03-22-2007, 07:23 PM   #4
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wiring a microwave


Quote:
Originally Posted by ron schenker View Post
I believe another code is you cannot have a receptacle in a cabinet with doors?
Where'd you find that one???

Where do you put your receptacles for OTR (over the range) microwaves?
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Old 03-22-2007, 07:42 PM   #5
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wiring a microwave


Your microwave must be at least 1000 watts. It should have a dedicated circuit.

You can illegally direct wire the microwave to the same box/source as the hood was wired to. It is done commonly, unfortunately because of the difficulty in fishing in a new circuit.

The fuse blowing probaby did not have a effect on the short life of the zapper.
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Old 03-22-2007, 08:15 PM   #6
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wiring a microwave


Quote:
Originally Posted by Speedy Petey View Post
Where'd you find that one???

Where do you put your receptacles for OTR (over the range) microwaves?
Must be a canadian thing. I'll look it up and get back to you, Petey
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Old 03-22-2007, 08:45 PM   #7
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wiring a microwave


Quote:
Originally Posted by darren View Post

Now i figured that out there is no way your microwave is only a 100W. It would take forever to cook your food, Maybe 1000W so that would be 8.3A.



Yes a thousand watts.

8.3 amps. So even if it is on a 15 amp breaker I have 5.7 amps or about 600 or so watts of other stuff left.

I seems odd to me that code would let me put a 1000 watt microwave on the counter on a shared line, but if it is mounted under a cabinet it needs a dedicated line.

Thanks for the info so far

Last edited by Jack Hass; 03-22-2007 at 08:52 PM.
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Old 03-22-2007, 08:55 PM   #8
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wiring a microwave


Quote:
Originally Posted by ron schenker View Post
I believe another code is you cannot have a receptacle in a cabinet with doors?
Never heard that before. Every over the range micro has a receptacle in the cabinet.

The microwave circuit is required by code to be a dedicated circuit, but in older existing houses, many counter top units are run on an existing circuit, and work ok as long as it is not used at the same time as other countertop appliances like toasters or ovens that will overload the circuit.

The old exhaust vent power is also frequently used, although not technically legal either, and also works until other appliances overload the circuit, which is almost never dedicated, especially in older houses. This was less of a problem when typical microwaves were 600 to 750 watts, but most modern units are 1000 watts or more.

Last edited by troubleseeker; 03-22-2007 at 09:03 PM.
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Old 03-23-2007, 05:18 AM   #9
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wiring a microwave


A microwave, by definition, most certainly does not require a dedicated circuit. This is until it becomes "fastened in place". Then it almost always does.

Actually, a 1000w micro wave does not technically require a dedicated circuit, but since it is in a kitchen there is usually no other option.
Good workmanship also tells us there is no other option.

See NEC 210.23(A)(2) & 210.52(B)(2)


Also, I cannot remember a time when it was legal to put a hood on the small appliance circuits.
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Old 03-23-2007, 05:26 PM   #10
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wiring a microwave


Here's what's in my little electrical book. Maybe I interpreted it wrong
Attached Thumbnails
wiring a microwave-microwave.jpg  

Last edited by ron schenker; 03-23-2007 at 06:14 PM.
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Old 03-23-2007, 06:14 PM   #11
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wiring a microwave


That is obviously not a real code book, but you may very well be correct....just not in the US.
There is no other safe way to plug in an OTR micro than to have the receptacle right in the cabinet above the micro.

Receptacles for micros in dedicated spaces are considered similar. They are not counted as counter space receptacles.
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Old 03-24-2007, 09:52 AM   #12
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wiring a microwave


I dug out my electrical code book .
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Old 03-24-2007, 06:45 PM   #13
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wiring a microwave


Like I said in my last post:
Quote:
....just not in the US.
We have no such blanket rule.

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