Range Hood / Outlet Question

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  #1  
Old 04-01-06, 11:10 PM
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Range Hood / Outlet Question

First off, this site is an amazing resource. I'm a somewhat new first time homeowner, and encountering my first electrical issue.

Here's what happened:

My wife was cooking, with range hood fan running. I was in another room. Range hood fan shuts off abruptly. Switch is still in the "on" position. I go to the circuit breaker box to flip the circuit that the hood is on (it was still in the "on" position). The switch has a red indicator on it (all other switches show no color in the "window").

I flip it to off, and then back on. I hear a pop. The electrical outlet immediately to the right of the range hood shows a little smoke, and then blackens around the edges. I assume the range hood is connected to this outlet. There was a toaster plugged into this outlet, but was not in use.

Immediately after this, a bit of grease or black liquid drops through the screen from the range hood, and onto the stove top. I take out the screen - it dripped off one of the screws holding the fan/motor on the range hood.

So far, I've checked the range hood to find a fuse, but didn't see one. Wiring comes directly from the wall, and straight to the switches, and then to the fan and light.

The outlet that blackened looks shot so I'll have to probably replace.

How should go about testing the range hood motor or whatnot to make sure this doesn't happen again? Is it shorted out from possibly some grease or liquid collecting on the motor? Any help is much appreciated, thanks!
 
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  #2  
Old 04-02-06, 12:50 AM
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> I was in another room.

Okay, you have an alibi.

> I go to the circuit breaker box to flip the circuit that the
> hood is on

Kudos to you for knowing which one.


> (it was still in the "on" position).

This is completely normal.


> The switch has a red indicator on it
> (all other switches show no color in the "window").

Very good.


> I flip it to off, and then back on. I hear a pop.

The breaker tripped again or the pop was elsewhere?


> The electrical outlet immediately to the right of the
> range hood shows a little smoke, and then blackens
> around the edges. I assume the range hood is
> connected to this outlet.

Okay.

> There was a toaster plugged into this outlet, but was not in use.

Okay.


> Immediately after this, a bit of grease or black liquid drops
> through the screen from the range hood, and onto the stove
> top. I take out the screen - it dripped off one of the screws
> holding the fan/motor on the range hood.

Okay.


> So far, I've checked the range hood to find a fuse, but didn't
> see one.

There is none.


> Wiring comes directly from the wall, and straight to the
> switches, and then to the fan and light.

Correct.


> The outlet that blackened looks shot so I'll have to probably
> replace.

Correct.


> How should go about testing the range hood motor or
> whatnot to make sure this doesn't happen again?

It will.

> Is it shorted out from possibly some grease or liquid
> collecting on the motor?

Not likely. Is it pretty old?


You have two problems.

1. The fan motor locked up and melted something (or melted something and locked up).
Did you try to touch it? Did you receive a second degree burn?


2. The connection from the receptacle to the fan is loose, quite possibly backstabbed.

When you reset the breaker, it overheated and either the breaker popped again or the connection burnt clear.


If this diagnosis is correct, you need a new motor (or range hood) and a new receptacle.
 
  #3  
Old 04-02-06, 07:54 AM
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I agree, you probably have to replace the range hood, You definitely have to replace the receptacle that is also damaged.
 
  #4  
Old 04-02-06, 09:31 AM
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Originally Posted by bolide
>
Not likely. Is it pretty old?


You have two problems.

1. The fan motor locked up and melted something (or melted something and locked up).
Did you try to touch it? Did you receive a second degree burn?


2. The connection from the receptacle to the fan is loose, quite possibly backstabbed.

When you reset the breaker, it overheated and either the breaker popped again or the connection burnt clear.


If this diagnosis is correct, you need a new motor (or range hood) and a new receptacle.
I checked the connection to the receptable - it wasn't backstabbed, it goes directly to screw terminals.

We the hood is about 10 years old - low end so I'm guessing it probably isn't worth it to just get a new motor, might as well get a whole new one.

I'll get a new receptacle and hood and give it a shot. Thanks so much for the help!
 
  #5  
Old 04-02-06, 09:54 AM
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Receptacles that are wired with the screws don't often burn up unless the screws are loose and/or the wiring is aluminum. It is entirely possible the receptacle is the problem and that the hood is involved only because it is on the same circuit. I think I'd give replacing the receptacle a try first.
 
  #6  
Old 04-02-06, 10:12 AM
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I agree with Bill. I see no 100% certain evidence that the hood is defective.

I'd take this opportunity to install GFCI receptacles on my countertop as well, if I were you.

I'd also update the panel schedule to indicate what breakers control what loads. It seems pretty apparent that your panel is mislabeled.
 
  #7  
Old 04-02-06, 11:46 AM
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Originally Posted by jumpmonger23
I checked the connection to the receptable - it wasn't backstabbed, it goes directly to screw terminals.
You need to determine the source of the smoke.
Was there absolutely nothing blackened in the box at all?
Can you post a photo of the blacked receptacle?
I don't understand which edges were blackened.
Is there any pitting on the screws, wires, or metal parts to indicate arcing?

If not from a connection or accidental contact, then you might have a short in the box connector.


Often when you get an overload such as a locked fan rotor, it blows the weakest link upstream.

There shouldn't be anything dripping from the fan, so that's a bad sign.
 
  #8  
Old 04-02-06, 11:48 AM
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Originally Posted by Rocky Mountain
It seems pretty apparent that your panel is mislabeled.
Why do you say this?
 
  #9  
Old 04-02-06, 11:50 AM
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Thanks for the advice guys. The outlet that burned up was GFCI. Would that indicate anything different?

Now, I was thinking more down the road - if the hood turns out to be the problem, most likely we'll want to move to a micro-hood since the rest of the kitchen could use the extra space.

It's my understanding that most microhoods require grounded plugs. I don't have any outlets in the cabinet above the hood, and the hood is connected directly via 2 wires. How difficult is it to install a properly grounded outlet in a cabinet above the hood? I don't have any problems taking off cabinets, cutting drywall, etc - just the electrical wiring I'd have to find a good resource for. Or is this something that requires a licensed electrican?
 
  #10  
Old 04-02-06, 12:21 PM
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Here are some pics of the burned up outlet.

here and here
 
  #11  
Old 04-02-06, 01:25 PM
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Originally Posted by jumpmonger23
The outlet that burned up was GFCI. Would that indicate anything different?
Maybe.

The GFCI didn't trip.
The points to either an overload downstream, a load to neutral fault, a fault upstream of the GFCI, a miswired GFCI, or a failed GFCI.

The location of the smoke is not consistent with a failed GFCI.

Where does the red wire go (hood or panel)?

A short in the receptacle box is unlikely. But you need to look carefully.



> It's my understanding that most microhoods require grounded plugs.

I should hope so.


> I don't have any outlets in the cabinet above the hood, and the hood is connected directly via 2 wires.

Interesting. Bad. But interesting.


> How difficult is it to install a properly grounded outlet in a cabinet above the hood?

Pull a new circuit from the panel.
 
  #12  
Old 04-02-06, 01:42 PM
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It appears that the arcing occurred on the load side neutral.

This indicates an loose connection with arcing initiatiated by an overload on the load side.

Looking closely, the wire does not appear to be correctly under the screw.

A close-up photo would be nice if you could.

It is possible that it has welded to the screw and feels solid.
It doesn't look like it necessarily always was.

So if the red wire goes to the hood only, then the most probable diagnosis remains an overload in the hood with collateral damage from arcing at an upstream loose neutral connection.

If the breaker is not AFCI, then it would not have tripped unless there was an overload.
 
  #13  
Old 04-02-06, 02:04 PM
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Originally Posted by bolide
So if the red wire goes to the hood only, then the most probable diagnosis remains an overload in the hood with collateral damage from arcing at an upstream loose neutral connection.

I've already removed the receptacle since I went to go get a replacement one.

The wires that power the hood are white, and black.

Is it safe to disconnect the hood for now, rewire a new receptacle and see if it works correctly with power?
 
  #14  
Old 04-02-06, 02:51 PM
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Originally Posted by bolide
Why do you say this?
In the original post he said "it" was still on. I thought "it" was the circuit breaker. On fourth read, I see that "it" was the hood. My mistake.
 
  #15  
Old 04-02-06, 02:57 PM
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> I've already removed the receptacle since I went to go get
> a replacement one.

Could you post a close-up of the inside of the box in the wall showing where the wires go?


Allow me to explain.

On a GFCI the two set of terminal (LINE and LOAD) have distinct functions.

You must wire them correctly.

If they were wrong before, you'll find out.


> The wires that power the hood are white, and black.

So where does the red wire go?
Is it pigtailed to the adjacent switch and to the hood?


> Is it safe to disconnect the hood for now, rewire a new
> receptacle and see if it works correctly with power?

Probably.
A burnt neutral on the LOAD side contraindicates a ground fault.

But why risk a new GFCI at all?

Just use two wire nuts.


When you do go to wire the GFCI, I suggest that you snip the burnt conductor loop, strip the insulation according to the guide, and backwire into the new GFCI.

The only reason not to do this is if the box is too shallow (less than 1.8").
 
  #16  
Old 04-02-06, 03:24 PM
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Ok, I'm obviously not an expert, this is what I can tell.

On the burnt receptacle:

Left top wire (white, burnt) heads left out of the box
Left bottom wire (white) heads out center back of box (there is a light switch directly on the other side of the wall)

Right top wire (red / purple) heads left out of the box
Right bottom wire (black) is pigtailed onto 2 wires, one of which heads left out of the box, and the other one heads down out of the box.

the adjacent switch isn't connected to any of the receptacle wires, nor was it used to control the hood.

I talked to another homeowner in the subdivision who's been around since they built the houses and he mentioned some quirky things with the electrical, so I might have to call someone in this case.
 
  #17  
Old 04-02-06, 03:36 PM
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Based on your pictures, I'd say that the poor termination of the wires on the GFCI receptacle was generating heat when the hood was on. Over time, the heat damaged the GFCI to the point where the circuitry inside the GFCI shorted, and kicked the circuit breaker.

I'd replace the GFCI, and put an ampclamp on the load side wiring, and determine if your hood is drawing more amps than it's nameplate rating.

Your hood is likely using the sheathing of the metallic cable as an Equipment Grounding Conductor. If the hood is drawing the normal amount of current, and this is an existing installation, it's likely fine the way it is. Test for continuity between the hood's metal frame and neutral to see if it's bonded.

It wouldn't hurt to have an electrician check this out.

FWIW, a readily available branch/feeder AFCI would not have tripped any sooner with this problem. It is only designed to detect parallel arcing faults over 75 amps, not series faults from a bad connection.
 
  #18  
Old 04-02-06, 08:47 PM
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So at this point, I decided to disconnect the hood, capping off the two wires that originally went to the hood.

I installed a new GFCI, and flipped the breaker. It seems all is OK at this point. Outlets work fine. Other than making sure the screw terminals are absolutely secure over the wire loops, what else should I check for in terms of terminating the wires correctly?


Originally Posted by Rocky Mountain
Your hood is likely using the sheathing of the metallic cable as an Equipment Grounding Conductor. If the hood is drawing the normal amount of current, and this is an existing installation, it's likely fine the way it is.
That's exactly what it is. Now if we go the microhood route, I'm guessing that metallic cable isn't good enough to provide power to a new outlet that needs to be installed? Like bolide said, I'll probably have to get somebody to pull a new circuit.
 
  #19  
Old 04-02-06, 09:56 PM
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Lucky me, I figured out what a "microhood" was before I exposed my ignorance on it. ("Why would a miniature hood cause a...? Why would someone want a tiny...? " )

Microwave/Hood combo? Yeah, that should be on it's own, I'd agree, get a new circuit for that.
 
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