GFCI question

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MDaug

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Bellevue, WA, USA
Is the lighting circuit in the garage required to be GFCI protected? Residential, new construction.
Dual Function GFCI / AFCI Ground Fault & Combination Arc Fault Circuit Breaker protection was seen in the electrical panel.
The garage lighting is on a AFCI circuit breaker.
Thanks
 
MDaug said:
Is the lighting circuit in the garage required to be GFCI protected? Residential, new construction.
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The branch circuit, itself, is not required to have GFCI protection. Any garage receptacle outlets placed for cord and plug connected luminaires, however, will require GFCI. Hardwired luminaires do not need GFCI.
 
brantmacga said:
furthermore, fluorescent strips can trip a GFCI........ most of the time.
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FIFY - I have seen some on GFCI that never give any troubles, not sure if it is the light, the GFCI, or other circuit conditions that contribute when there is trouble in this area.
 
My entire garage is on GFCI. That's fluorescent, CFL and LED lights included along with a merc vapor outside light. The LED bulbs are in a motion detector. No problems. I also run grinders and drills with no issues.

In the house, my washer, dryer and an air compressor are on GFCI's with no problems.
 
In my experience, it's more of a rarity that a fluorescent ballast won't trip a gfi, being they use the EGC to start the lamps.

We just did a couple of houses (for the first time in years) where no one noticed that every 20/1 breaker sold in the panel was DF afi/gfi. Not a single fluorescent fixture didn't trip the gfi.


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brantmacga said:
In my experience, it's more of a rarity that a fluorescent ballast won't trip a gfi, being they use the EGC to start the lamps.

We just did a couple of houses (for the first time in years) where no one noticed that every 20/1 breaker sold in the panel was DF afi/gfi. Not a single fluorescent fixture didn't trip the gfi.


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The EGC does assist starting lamps, but it is not a case of supply current to the ballast being routed through the EGC in any way, which is what would be needed to throw current balance enough to trip in the CT coil of the GFCI. In the case of magnetic ballasts the lamps may even be on a separately derived source as in total electrical isolation between primary ballast winding and secondary lamp winding(s).
 
GFCI question

kwired said:
The EGC does assist starting lamps, but it is not a case of supply current to the ballast being routed through the EGC in any way, which is what would be needed to throw current balance enough to trip in the CT coil of the GFCI. In the case of magnetic ballasts the lamps may even be on a separately derived source as in total electrical isolation between primary ballast winding and secondary lamp winding(s).
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I wonder why we had so many issues with it then?


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Edit to add..... In the course of troubleshooting, we lifted the grounds off the fixture and the breaker held, so my assumption was the EGC being used to start the lamp.


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brantmacga said:
Edit to add..... In the course of troubleshooting, we lifted the grounds off the fixture and the breaker held, so my assumption was the EGC being used to start the lamp.


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Maybe you had some inductive kickback, or other activity on the line side of the ballast, if it is secondary current of a true isolation transformer it shouldn't matter to the GFCI.
 
kwired said:
Maybe you had some inductive kickback, or other activity on the line side of the ballast, if it is secondary current of a true isolation transformer it shouldn't matter to the GFCI.
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But AFAIK most ballasts are not wound for isolation.
During starting, before the arc has ignited the full length of the tube, some current will flow via a shortened arc path from one electrode to the walls of the tube via capacitive coupling between the interior of the glass and the nearby grounded metal reflector.
This current is small, but very helpful in starting the arc in the first few cycles after power is applied.
I think it is needed only for rapid start and other modes which do not provide a high voltage inductive kick to ignite the full length arc.
 
GoldDigger said:
But AFAIK most ballasts are not wound for isolation.
During starting, before the arc has ignited the full length of the tube, some current will flow via a shortened arc path from one electrode to the walls of the tube via capacitive coupling between the interior of the glass and the nearby grounded metal reflector.
This current is small, but very helpful in starting the arc in the first few cycles after power is applied.
I think it is needed only for rapid start and other modes which do not provide a high voltage inductive kick to ignite the full length arc.
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At what current level is this leakage? Maybe it does reach high enough level for GFCI trip if there are several lamps starting at same time, single or double lamp luminaire probably isn't likely to leak that much current.
 
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