Garage door shock

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Old 07-15-16, 10:19 PM
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Garage door shock

Friend's home. Touched garage door track (while barefoot) and received a small shock.

Garage door opener is plug-in (as opposed to hardwired). Unplug opener and shock goes away. Plug back in and shock comes back.


Does this mean opener has short/problem, or might there be an issue on the branch circuit itself? If the latter, how would you go about finding source of the problem?
 
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Old 07-15-16, 10:29 PM
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Does the door opener have a three prong plug on it ?
If yes... is the three pronged plug plugged into a three prong receptacle ?

If yes again.... the ground would appear to be missing from the receptacle.
Also... the unit appears to have a slight voltage leak which could signify a problem.
 
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Old 07-16-16, 07:16 AM
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It might also happen if the receptacle has a bootleg ground. You could try running a long 3 wire extension cord to a GFCI outlet and see what happens.
 
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Old 07-16-16, 07:41 AM
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3-prong plug in 3-prong outlet

Is the problem likely:
Missing ground? If so, how to check if there is ground wire in the box? (Haven't checked yet. Will not be able to get there until Monday) edit to clarify: I know how to check if a ground wire exists. I a, asking how do I check if the ground connection is missing if a ground wire is present.

Problem in door opener?

Problem elsewhere in line?



How do I determine actual source of voltage leak? I have a multimeter.just not sure where to place the leads to troubleshoot this issue?
 

Last edited by jrm21; 07-16-16 at 08:57 AM.
  #5  
Old 07-16-16, 11:20 AM
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I'm willing to bet it's the opener that's bleeding current to ground. A good check is to do as suggested and power the opener with an extension cord from a GFCI outlet. If there is any power bleed to ground the GFCI will trip.
 
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Old 07-16-16, 12:06 PM
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Yes... the opener is leaking power to ground but if the ground was correct there would be nothing felt.

You'd need a three wire extension cord. Plug it into a known working three wire receptacle with ground. The third wire..... round pin.... would be your known ground reference.

Using your meter on the AC scale..... check from the round/ground hole to the plugged in door opener. What do you measure ?

Now check from the round/ground hole to the plate screw of the garage door opener receptacle.
What do you measure ?
 
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Old 07-16-16, 06:11 PM
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Is the problem likely: Missing ground?
A missing ground is a problem, but a missing ground will not cause a voltage leak nor will adding a ground fix a voltage leak. If you determine the voltage is leaking inside the opener, the best fix is to replace the opener.
 
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Old 07-18-16, 06:59 AM
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the best fix is to replace the opener.
It is likely a fault in the opener. Just to add, current code calls for the opener to be on a GFCI protected circuit. In this case it should trip and you wouldn't get shocked.
 
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Old 07-18-16, 11:13 AM
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First off... Apologies for the brain freeze. I realize a missing ground would not cause the problem. Somehow I misinterpreted an answer and inferred that's what someone wrote.

I followed the suggestions here and am not sure what is going on.

One thing I don't pla to try is touching the door while barefoot.

1. Plug door opener into working gfci receptacle via extension cord. Gfi does not trip. Garage door works as normal.


2. Test original receptacle with nothing plugged in:
A. Hot to neutral. 118.5v
B. Hot to ground. 118.5v
C. Neutral to ground. 0v

3. Test with door opener plugged into gfi via extension cord and nothing plugged into original outlet:

A. Receptacle neutral to garage door metal: 117v
B. Receptacle ground to garage door metal: 117v
C. Receptacle hot to garage door metal: 0v

4. Test with door opener unplugged and nothing plugged into original outlet:

A. Receptacle neutral to garage door metal: 17v
B. Receptacle ground to garage door metal: 17v
C. Receptacle hot to garage door metal: 1.5v

Just for kicks, I tried one more scenario...

5. Test with door opener plugged into a different non-gfi circuit via extension cord and nothing plugged into original outlet. Original out has breaker turned off for this test:

A. Receptacle neutral to garage door metal: 10v
B. Receptacle ground to garage door metal: 10v
C. Receptacle hot to garage door metal: 10v


All testing done with a southwire digital multimeter set to ac voltage. Using junction box screw yielded same results as using found hole in receptacle.

Any ideas are much appreciated. I am thinking this is a dangerous situation.
 

Last edited by jrm21; 07-18-16 at 11:37 AM.
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Old 07-18-16, 11:35 AM
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Back with one more comment...

I have been trying to isolate things by turning off different circuits in the house. What I have found is:

When door opener is plugged into a circuit that is turned OFF I get a reading of 118v between door opener metal part and door opener receptacle junction box (metal).

When door opener is plugged into its normal receptacle, I get a reading of 0v
between door opener metal part and door opener receptacle junction box (metal).

When door opener is plugged into different receptacle on same beach circuit as original, I get a reading of 17v
between door opener metal part and door opener receptacle junction box (metal).
 
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Old 07-18-16, 12:29 PM
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One more thing....

Just pulled the receptacle. Testing the garage door line with just bare wires connecting to the test leads.

Black to white shows 117.5v
Black to ground shows 1.5v
White to ground shows .8v

This is different than the original measurement from the outlet. It is the second to last outlet in the line... Only a light was wired after that. Since the receptacle has been removed, other outlets in the same branch circuit show similar voltage readings.
 
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Old 07-18-16, 12:57 PM
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When door opener is plugged into a circuit that is turned OFF I get a reading of 118v between door opener metal part and door opener receptacle junction box (metal).
The door itself may be getting energized. Could any nearby wiring have been penetrated by nail or other hardware? What kind of siding is on the garage?
 
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Old 07-18-16, 02:13 PM
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The door itself may be getting energized. Could any nearby wiring have been penetrated by nail or other hardware? What kind of siding is on the garage?
Vinyl siding on the outside of the home. Garage is on a slab - nothing underneath. Every part of the garage door and opener is connected to solid wood. I had a similar thought and looked at every point of contact. I don't see how there could be an accidental connection to another wire.


When I disconnected the receptacle, I noticed that the hot/neutral connection was reversed. I fixed that when putting it back together. I also suspect that the ground wire was making contact with the neutral wire in the junction box (which originally gave me a voltage reading).

Anyway.... there is currently no shock from the garage door. I went to far as to go barefoot and test (even wet my hands and feet).


I suspect there is a problem with the ground wire somewhere. All the outlets I can find on that branch circuit have 3 wires properly connected. However, none show full voltage between hot and ground (only hot and neutral). Either there is a disconnect in a light fixture on that circuit, or the ground wire doesn't run all the way back to the panel. It is a house originally built with a 2-wire system. This section of the home has all new 3-wire romex, but I suppose it is possible someone wired it as an extension to a 2-wire circuit and the ground wire doesn't run all the way home.

Is this a logical conclusion? I'm basically ready to call in an electrician unless there are some other simple things I can try to track down the issue.
 

Last edited by jrm21; 07-18-16 at 02:55 PM.
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Old 07-19-16, 07:51 PM
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Question, is the carrier and disconnect arm pieces metal or plastic? The newer ones I think are all plastic and will isolate the motor from the actual door. Older ones are metal and will of course connect them. Might add a piece to the puzzle.


Also note that the 10v and 17v readings that you're getting might need to be taken with a grain of salt. Digital voltmeters commonly read what's called phantom voltage, which may not actually be there.
 
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Old 07-19-16, 11:20 PM
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Not sure exactly what the carrier or disconnect arm are. Everything outside the opener housing is metal. The entire disconnect assembly is metal, except for the string and handle.

Phantom voltage... I figured that was a possibility. Just wanted to include all readings to be complete.

I have a feeling the problem was due to a few problems in the receptacle box which have been corrected.

Some work was done in the home recently. Either the previous homeowner extended this line off an ungrounded circuit or the ground connection was broken during the recent work (they installed some new light fixtures). We are going to have the contractor come back with his electrician to resolve the missing ground issue. In addition, we plan to replace the garage door outlet with a gfci receptacle.
 
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Old 07-20-16, 11:04 AM
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we plan to replace the garage door outlet with a gfci receptacle.
On the garage ceiling? That would be another code violation.
 
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Old 07-20-16, 11:26 AM
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Actually, it is on the wall.

Are you stating that a ceiling receptacle is against code, or just a GFI receptacle? I'm guessing the latter as that would require a ladder to reset the outlet.

The outlet in question is not at floor level, but reachable without a ladder. Is there a specific height I need to be aware of? If so, it would make more sense for me to put the GFI outlet further "downstream" at typical level.
 
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Old 07-20-16, 01:36 PM
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I'm guessing the latter as that would require a ladder to reset the outlet.
Yes, that is correct. You can run it from the load side of another GFCI receptacle or deadface GFCI or a GFCI breaker.
 
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Old 07-21-16, 03:30 PM
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we plan to replace the garage door outlet with a gfci receptacle.

On the garage ceiling? That would be another code violation.

Actually, it is on the wall.
And the opener's cord is long enough to reach the wall outlet without an extension cord? Remember, extension cords are only for temporary use.
 
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Old 07-21-16, 03:59 PM
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And the opener's cord is long enough to reach the wall outlet without an extension cord? Remember, extension cords are only for temporary use.
No extension cord. I figured that was a given. Opener cord supported along wood beam and connected directly to outlet. Pretty easy for me to reach without a ladder, but probably not so for a short person. That's why I asked about height requirements for GFI outlets. Accessibility can be a relative term if not defined.
 
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Old 07-21-16, 04:06 PM
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Accessibility can be a relative term if not defined.
IIRC NEC says 6'7" (~ 2 meters).
 
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Old 07-21-16, 04:27 PM
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Thanks, Ray. It probably misses that by a little bit, so I will go with the previous suggestion of installing the GFI outlet further upstream.
 
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Old 07-21-16, 04:29 PM
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No extension cord. I figured that was a given. Opener cord supported along wood beam and connected directly to outlet.
That sounds like you are good. I don't think I've seen an opener cord longer than about 5 feet, but there easily could be longer ones out there. I've also seen many extension cords used that had been in place for 20 or more years.
 
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