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-   -   Replacing old hood with over-the-range microwave (http://www.diychatroom.com/f18/replacing-old-hood-over-range-microwave-112905/)

Nathan0115 08-04-2011 01:47 AM

Replacing old hood with over-the-range microwave
 
So I just bought a nice new over the range microwave and installed it myself with some help.

Everything went relatively smoothly except for when I wired the outlet.

The old hood was hardwired so when I took it down I shut off the breaker, drilled a hole in the cabinet above, and ran the wires up. I figured when I was done installing the microwave, I'd simply mount a box inside the cabinet and hook the wires up to an outlet so that I could plug in the new microwave.

I did all this, plugged the microwave in and went downstairs to turn on the breaker. My wife said that when I flipped it back on, a shower of sparks came from the outlet and the microwave did not turn on. If I run an extension cord to power the microwave elsewhere it works fine. Based on what shut off when I turned off the breaker, this ciruit is shared with one outlet in the kitchen plus (off all things) the washing machine in the basement. Neither of these things was being used at the time, nor did the breaker re-trip. Just sparks and no power.

I'm at a loss. What did I do wrong?

dSilanskas 08-04-2011 05:44 AM

Take the outlet box apart that you made up. Make sure you don't have the hot touching the sides of the metal box.

Just Bill 08-04-2011 07:28 AM

What he said. I suspect hot was touching the box, neutral, or ground and made sparks. It should be obvious when you open the box. Did it trip the breaker??

Nathan0115 08-04-2011 09:37 AM

Well that's the weird part. It did not trip the breaker.

What's more, I only get the spark shower if something is plugged into the outlet I rigged when I turn the power on.

If there was a short circuit in the box, I would be seeing the big pop regardless of what's plugged in there, yes?

seansy59 08-04-2011 10:01 AM

Keep the breaker off for now.
I am Not an electrician

When you have sparks like that, it's not very likely that something is overloaded. That means theres a dead short in contact with metal/ground. When something is overloaded, your breaker will trip which is overcurrent.

First, I take it that your gang box is metal?
Check that there is NO bare wiring or screws touching the box. Bare wire to green screw (Ground), black to brass screw (Hot), white to silver screw(neutral)

- If that still causes a problem, then your outlet may be faulty. Try a new outlet?

- Maybe there is a knick in the wires touching something, that may have
happened when you moved the wire/fan.

md2lgyk 08-04-2011 11:44 AM

If I were you, I'd run a separate circuit for the microwave. The way the circuit you tied into is shared, I guarantee the breaker will trip if you try to nuke something while the washer is running.

gregzoll 08-04-2011 12:14 PM

Quote:

Originally Posted by md2lgyk (Post 700171)
If I were you, I'd run a separate circuit for the microwave. The way the circuit you tied into is shared, I guarantee the breaker will trip if you try to nuke something while the washer is running.

Also sharing with the washer is not code compliant.

electures 08-04-2011 12:27 PM

Quote:

Originally Posted by seansy59 (Post 700127)
Keep the breaker off for now.
I am Not an electrician

When you have sparks like that, it's not very likely that something is overloaded. That means theres a dead short in contact with metal/ground. When something is overloaded, your breaker will trip which is overcurrent.

First, I take it that your gang box is metal?
Check that there is NO bare wiring or screws touching the box. Bare wire to green screw (Ground), black to brass screw (Hot), white to silver screw(neutral)

- If that still causes a problem, then your outlet may be faulty. Try a new outlet?

- Maybe there is a knick in the wires touching something, that may have happened when you moved the wire/fan.


WHen you take the box apart look for any indication of the short such as blackened areas around the connector or terminals.

electures 08-04-2011 12:29 PM

Quote:

Originally Posted by md2lgyk (Post 700171)
If I were you, I'd run a separate circuit for the microwave. The way the circuit you tied into is shared, I guarantee the breaker will trip if you try to nuke something while the washer is running.

Check the manufactures installation instructions and see if they require or recommend a seperate circuit. Now may be the time to install one.

HouseHelper 08-04-2011 02:53 PM

Since an over the range microwave is also a hood, and it is cord and plug connected, then the circuit supplying it should be an individual i.e., dedicated, branch circuit. (see 422.16(4))

Dwillems 08-04-2011 06:32 PM

Sounds like it may be wired wrong if it only happens with something plugged in. I'm no electrician so I look it up every time. The hot and neutral go on opposite sides of the outlet on a specific side. And the ground has it's own separate green colored screw

gregzoll 08-04-2011 06:41 PM

Quote:

Originally Posted by Dwillems (Post 700429)
Sounds like it may be wired wrong if it only happens with something plugged in. I'm no electrician so I look it up every time. The hot and neutral go on opposite sides of the outlet on a specific side. And the ground has it's own separate green colored screw

Yes, it is Black to Brass, White to Silver.

electures 08-04-2011 07:35 PM

Try plugging something else in. Maybe there is a short in the appliance.

Missouri Bound 08-04-2011 11:46 PM

The appliance is (at least it was) fine. You have a hot wire touching to ground. Could be another wire, could be the box. Inspect the box for any blackened areas. Did you use stranded wire, by chance?

jbfan 08-05-2011 07:21 AM

Where did the power come from?
If it sparks only when something is plugged in, you could have pulled from a switch leg!


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