# dentist office ??'s



## donselec (May 7, 2011)

i got a call to check a few outlets that were tripping the gfi breaker.
get there and its a 4"sq dbl duplex on floor under a cover that runs the chair,
water pick,drill and light. took apart couldn't find anything but kept tripping.
swapped gfi breaker and still tripped.replaced with regular breaker and it holds.
does this even require gfi protection??

2nd problem

they retiled wall in sterilization area and pulled gfi's out and sparks flew so they 
replaced it and it didnt work. i pull it out and its mis wired. these were hospital grade gfi's one circuit with 4 of them. they replaced with just a regular one.
does that room require hospital grade outlets ?? 

thanks


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## erics37 (May 7, 2009)

I'm not sure on the answers to your questions but if something is tripping the GFCI breaker consistently, replacing it with a regular breaker is NOT the solution. Especially when it supplies stuff that goes in people's mouths. You need to unplug/disconnect equipment one at a time to determine which one is making the breaker trip.


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## donselec (May 7, 2011)

it ran for a week or two with no issues and would randomly trip i figured 
it just didn't work with gfi for some reason but i couldn't find anything and they haven't had any problem since. i was worried about it and took meter readings 
from everywhere and had no voltage issues....gonna get a new gfi breaker and try it again...im at a loss on this....maybe internal chair wire ??


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## walkerj (May 13, 2007)

Megger


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## erics37 (May 7, 2009)

Yeah unplug everything and megger the circuit.


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## walkerj (May 13, 2007)

If I was at the dentist and got lit up in my mouth and they said 'oh well our electrician just fixed the wiring'
I would say 'awesome! Who was it?'
If they told me it was you, I would hunt you down and beat you half to death with the radio shack meter you carry in your 92 hatchback. 

This was not directed to the OP, just the situation.


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## RePhase277 (Feb 5, 2008)

Ground fault tripping means something is leaking to ground. Megger it.

Hospital grade receptacles are only required in areas where patient beds are located. So, unless the chair has unconscious people in it, you don't need hospital grade.


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## vizzolts (Sep 10, 2009)

If it were me I'd probably open up a receptacle for testing and place a good high impedence multimeter in series in the equipment ground path. Then test each load being plugged into the tripping GFCI and measure milliamps and millivolts with it turned on. The load that is tripping the GFCI will likely show some current leakage/voltage potential to ground. If you can't find anything via this method then megger the circuit like the others said I suppose, I've personally never solved the problem of a tripping GFCI by finding compromised insulation in the branch circuit that feeds it but I suppose with some inductive leakage that could cause the problem.


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## vizzolts (Sep 10, 2009)

Another thing that you could do first is throw a good meter from the hot/neut pins on the appliance plugs to ground. Anything lower than high K or MEG Ohms could possibly identify the problem.


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## manchestersparky (Mar 25, 2007)

InPhase277 said:


> Ground fault tripping means something is leaking to ground. Megger it.
> 
> Hospital grade receptacles are only required in areas where patient beds are located. So, unless the chair has unconscious people in it, you don't need hospital grade.


Not so fast.........

There is a good bit of dental equipment that has tags on the cords that state they must be plugged into hospital grade receptacles. Most of the dental chairs I inspect have those tags..
If it has the tag then a hospital grade receptacle is required

The good old listing and labeling thing


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