# Low voltage lights tripping CAFI



## JBrzoz00 (Nov 17, 2013)

Has anyone had issues with a low voltage transformer (in my case a magnetic one) intermittently tripping a CAFI breaker? Seems to only trip if lights have been off for a while and then get turned on.


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## joebanana (Dec 21, 2010)

Why do you have a lighting xfmr. on a CAFI ?(AFCI?)


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## 480sparky (Sep 20, 2007)

Never heard of 12v landscape lighting transformers that plug into a receptacle?

CAFI=Combination Arc Fault Interrupter.

The inrush current may be tripping the GFCI portion that's built in to many AFCIs.


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## JBrzoz00 (Nov 17, 2013)

I mean CAFI as in the kind that detect series and parallel faults not the afci/gfci combos. Only does this on 2 circuits, I have other circuits with the same transformers and the same CAFI breakers, they don't trip intermittently.


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## macmikeman (Jan 23, 2007)

What brand arc fault breakers , what brand transformers, for starters.


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## Service Call (Jul 9, 2011)

480sparky said:


> Never heard of 12v landscape lighting transformers that plug into a receptacle?
> 
> CAFI=Combination Arc Fault Interrupter.
> 
> The inrush current may be tripping the GFCI portion that's built in to many AFCIs.




They're readily available and in abundance.


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## 480sparky (Sep 20, 2007)

Service Call said:


> They're readily available and in abundance.



What is? Landscape lights? Receptacles? Combination AFCI breakers? 12v transformers?


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## Service Call (Jul 9, 2011)

12v landscape transformers that plug in.


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## 480sparky (Sep 20, 2007)

Service Call said:


> 12v landscape transformers that plug in.


And the relevance of that is...........? :blink:


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## Service Call (Jul 9, 2011)

480sparky said:


> Never heard of 12v landscape lighting transformers that plug into a receptacle?QUOTE]
> 
> 
> Just responding to your question.


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## daks (Jan 16, 2013)

Swap the CAFI breakers around see if the problem follows the breaker.


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## JBrzoz00 (Nov 17, 2013)

Swapped breakers and the problem does not change. I have it nailed down to the transformers. Breakers are square d qo style.


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## Majewski (Jan 8, 2016)

Does any load trip afcis or just this/these transformers?


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## Service Call (Jul 9, 2011)

One other thing, these transformers are meant for outdoor applications. Why is there an AFCI involved?


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## lighterup (Jun 14, 2013)

Service Call said:


> One other thing, these transformers are meant for outdoor applications. Why is there an AFCI involved?


I wondered the same thing , then thought maybe installer pulled 
120v power from an indoor source , probably sharing the same 
external wall.
I would not do it this way but just guessing.
If I were the installer , I would put landscape transformer lighting
on its own 20 amp gfci protected circuit (or WP gfci).

Having said all of this , I am not even sure original post is talking
about outdoor landscape low voltage lighting. The lighting was not
specified , just the transformer. To my knowledge those are rated
for outdoor use only.


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## JBrzoz00 (Nov 17, 2013)

It's just these transformers, one is for some post lights on the front steps on the foyer entry circuit. 

One is on the 2nd floor living room circuit for the 2nd floor deck post lights on the living room circuit.

I have a 3rd that is for some post lights on a 3rd floor deck, this one has never tripped the afci.

Transformers are rated for indoor/outdoor. The 120 plug in is only 2 wire, no ground.


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## MikeFL (Apr 16, 2016)

Try contacting the xfrmr manufacturer and see what they say.


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