# Replacing old hood with over-the-range microwave



## Nathan0115 (May 7, 2010)

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?


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## dSilanskas (Mar 23, 2008)

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


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## Just Bill (Dec 21, 2008)

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??


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## Nathan0115 (May 7, 2010)

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?


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## Ohno59 (May 4, 2011)

*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.


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## md2lgyk (Jan 6, 2009)

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.


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## gregzoll (Dec 25, 2006)

md2lgyk said:


> 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.


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## electures (Dec 22, 2009)

seansy59 said:


> *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.
> ...


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


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## electures (Dec 22, 2009)

md2lgyk said:


> 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.


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## HouseHelper (Mar 20, 2007)

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))


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## Dwillems (Jul 14, 2011)

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


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## gregzoll (Dec 25, 2006)

Dwillems said:


> 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.


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## electures (Dec 22, 2009)

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


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## Missouri Bound (Apr 9, 2011)

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?


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## jbfan (Jul 1, 2004)

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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## PureCountry (Jul 27, 2012)

I'm installing a over range microwave and have no idea how to do the hardwire .. Help!


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## Jim Port (Sep 21, 2007)

You will install an outlet in the cabinet above the microhood on a dedicated breaker. You will run a 15 or 20 amp cable from the location to the panel and install a new single pole breaker.


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## stickboy1375 (Apr 28, 2012)

gregzoll said:


> Also sharing with the washer is not code compliant.


Why not? We only need to supply a 'Laundry Circuit' no where is it stated that it is for the washing machine.... with that said, if the loads met the circuit criteria I don't see any violation.


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## stickboy1375 (Apr 28, 2012)

HouseHelper said:


> 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))


I disagree, a microwave range hood is not what 422.16 (4) is referring to, nor was intended to.


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## Jim Port (Sep 21, 2007)

Stickboy,

The laundry circuit is restricted to the laundry area only.

(2) Laundry Branch Circuits. In addition to the number
of branch circuits required by other parts of this section, at
least one additional 20-ampere branch circuit shall be provided
to supply the laundry receptacle outlet(s) required by
210.52(F). This circuit shall have no other outlets.

How would you get around the 422.16(4) requirement? The instructions for the MWH would also call for a dedicated circuit.


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## electures (Dec 22, 2009)

Why not add it to the D/W and disposal circuit?


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## stickboy1375 (Apr 28, 2012)

Jim Port said:


> Stickboy,
> 
> The laundry circuit is restricted to the laundry area only.
> 
> ...


Jim, you cannot assume the washer is utilizing the required laundry branch circuit. This was my point to begin with when someone said is was a code violation to have anything else on the washing machine circuit. 



Jim Port said:


> How would you get around the 422.16(4) requirement? The instructions for the MWH would also call for a dedicated circuit.


422.16(4) does not include microwave hoods, only range hoods, there is a difference, and this is why 422.16(4) exists to begin with, also, you cannot assume a microwave hood will call for a dedicated circuit.


With that said, im all for a dedicated circuit, but it seems sheepish for the nec to require such nonsense, since I can buy a standard microwave and place it on my counter and plug it in to any small appliance circuit shared with other appliances...


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