Arc-Fault / Plug in transformers

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DUCKMAN

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I am told that in the 2008 NEC, Arc fault breakers will be required in all residential circuits. Some jursidictions have already made this a requirement. My question is, are there any problems with using a plug in transformer on an arc fault protected outlet? They cannot be used on a GFCI protected outlet, but I have never needed to plug into an arc fault circuit.
 
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DUCKMAN said:
They cannot be used on a GFCI protected outlet, but I have never needed to plug into a arc fault circuit.
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Why not? My electric razor has a transformer and it works just fine on a GFI.
 
They cannot be used on a GFCI protected outlet,
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Where are you getting this information?

I don't see that there will be a problem with installing a transformer on an AFCI protected circuit. JMHO.

Chris
 
arc fault

arc fault

mikeames said:
Why not? My electric razor has a transformer and it works just fine on a GFI.
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The GFI will trip at irregular intervals if a low volt transformer (such as for an alarm panel) is used. The GFCI is fooled into thinking there is a ground fault by the transformer. The NEC allows an exception for non-GFCI outlets in a residential basement if the outlet is dedicated to an alarm system.
 
Duckman,
The GFI will trip at irregular intervals if a low volt transformer (such as for an alarm panel) is used. The GFCI is fooled into thinking there is a ground fault by the transformer.
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Can you cite a technical source for your statement? The GFCI only sees the primary winding of the transformer and that will not cause a trip.
Don
 
DUCKMAN said:
I am told that in the 2008 NEC, Arc fault breakers will be required in all residential circuits. Some jursidictions have already made this a requirement. My question is, are there any problems with using a plug in transformer on an arc fault protected outlet? They cannot be used on a GFCI protected outlet, but I have never needed to plug into an arc fault circuit.
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They work just fine on AF circuits. The only plug in transformers that will sometimes trip a GFCI are the AC to DC type plugins. My guess is it has something to do with the rectifier causing an imbalance. JMO.
 
Yeah, that's a new one on me.

Now I'll have to go home and plug all sorts of wierd stuff into the bathroom outlet just to see. Do I need the water running for this test? :)



"I knew I was an unwanted baby when I saw that my bath toys were a toaster and a radio."

Joan Rivers
 
No technical back-up, just experience. After 15 years of installing alarms, we have learned. They do not always trip, but in some cases they will trip at pretty regular intervals. This is the primary reason for the exception for alarm outlets in residential basements
 
My sprinkler system transformer is plugged into a GFCI protected circuit and has never tripped in 10 years of service. (And yes, I do test it on occasion).:roll: Add to that the cordless phone transformers in my garage and workshop. Same scenario, 5 years never tripped.
 
iwire said:
Chris where is the other current path that would be necessary for an imbalance to happen?
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You got me? All I know is it's been a problem on several occasions that plugging in a cordless phone charger has tripped a GFCI but then won't trip one in another area. At first I thought it was a bad t-former but plugging it into another GFCI it never tripped. and the GFCI that tripped never tripped with anything else plugged into it. I can still plug the t-former into it and it will trip today, I just did it a few minutes ago. So Why?
 
Chris6245 said:
You got me? All I know is it's been a problem on several occasions that plugging in a cordless phone charger has tripped a GFCI but then won't trip one in another area. At first I thought it was a bad t-former but plugging it into another GFCI it never tripped. and the GFCI that tripped never tripped with anything else plugged into it. I can still plug the t-former into it and it will trip today, I just did it a few minutes ago. So Why?
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Either the plug is a 3-wire and there is an internal leak, or there is a primary-to-secondary leak and line current is entering the phone line.
 
DUCKMAN said:
My question is, are there any problems with using a plug in transformer on an arc fault protected outlet? They cannot be used on a GFCI protected outlet, but I have never needed to plug into an arc fault circuit.
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The reason they cannot be supplied by a GFCI protected receptacle is because 760.21 & 760.41 prohibit it. Exception 3 to 210.8(A)(5) was added to allow FA panels to be installed in unfinished basements and still meet the requirements of Article 760. I think NFPA 72 has a similar requirement.

For now, I don't think there's anything that prohibits a FA system to be supplied by an AFCI protected circuit.
 
Both 760.21 & 760.41 include the sentence:
These circuits shall not be supplied through ground-fault circuit interrupters or arc-fault circuit interrupters.
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LarryFine said:
Either the plug is a 3-wire and there is an internal leak, or there is a primary-to-secondary leak and line current is entering the phone line.
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I agree. :)

Assuming a properly functioning GFCI it can not trip unless the current finds another path.
 
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