Track lights and ACFI

n00bhomeownerOctober 29, 2010

I have track lighting in my kitchen and when i turn it on, it trips the breaker for my computer room upstairs. After the computer room breaker is tripped (and thus no pwr in that room), the track lighting stays on, so i know the track lighting isn't on the same breaker as the computer room. now with the track lights still on and the breaker tripped for the computer room, if i reset/flip the breaker for the computer room back on, the computer room pwr comes back on and the track lighting and the computer room both have power with no problems. now if i flip off the breaker for the track lighting (and all my other kitchen lights) while the track lighting is still on and then flip the breaker back on, the computer room and track lighting once again exist in harmony. wtf is going on? i will love you to death if you can explain to a n00b why these magical things are happening.

originally, i called a tech out because the track light wasn't coming on correctly - it would flicker or not come on - and it would trip the computer room breaker. when the tech came, this is what he wrote on his service invoice "tracklighting loose connection tightened this also fixed breaker being it is an AFCI". All he did was tighten a screw on the track lighting itself (the loose connection) so that the lights now come on properly, and then flip the breaker for the computer room back on. with the power working for both the computer room and the track lighting, he left with us all believing the problem was fixed. the next time i turned the track lighting on, however (and as described above), i found it was still tripping the computer room breaker as before. what could he have been referring to when he said "also fixed breaker being it is an AFCI". does "fixed" breaker just mean he flipped/reset the computer room breaker? b/c that's all he did and only my bedrooms (one of which is the "computer room") have ACFI breakers.

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I know I sound like a nut job- but just try this to see.

UNplug all your computer gear-including any modems/routers/phones/stereos/alarm clocks etc.

If necc. leave a lamp plugged in.

Now try turning on the track light again- did it trip this time?

If it didn't, you may need a new afci or possibly move some(usually cable or DSL modems for some reason) or all of your computer equipment to another circuit that is non AFCI protected(depending on the breaker manufacturer). If it did, you need a better electrician(maybe you need that either way).

I have seen this before. Digital interference causing nuisance trips on AFCIs.

    Bookmark   October 29, 2010 at 9:32PM
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If I'm not mistaken, AFCIs also have a GFP (20+ma, IIRC) function. A remote possibility is that the kitchen light circuit borrows a neutral from the computer room circuit. When you turn on the light, it imbalances the h/n current in the computer room circuit, which would trip the GFP.

This could happen if the two circuits were combined in a junction box and the neutrals were connected together. It could also happen in an older home with some knob and tube wiring.

    Bookmark   October 30, 2010 at 1:10AM
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Ron Natalie

David is right, the AFCI will trip on substantial ground fault (it's actually 30mA as opposed to 4-6 for a GFCI). Booting the neutral or even neutral to ground connections after the device will be more than enough to trip it.

    Bookmark   October 30, 2010 at 10:34AM
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