AFI Tripping with Computer


Old 03-14-11, 06:08 AM
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AFI Tripping with Computer


We are in the process of moving our home office into a bedroom and upon doing it we discovered that the computers are all tripping the AFI. The tripping is inconsistent but seems to be pretty frequent. I would say 2 out of 10 times the AFI is not tripped. I have tested it with two computers and both computers caused the same problem so I think I can safely rule out the problem being with the computers. Should I replace the AFI breaker or is there something else I should be doing? I am wondering if the power supply fans are perhaps causing an arc? I am not all that familiar with AFI's or how they work. I've read up on them a little bit but up until yesterday I had no idea such a thing was even common in homes. Anyway hopefully someone can shed some light. So far I've had very little luck finding information online.

Oh also, I used an amp meter on the line and can confirm that the problem was not overloading. On one of the times I was able to get both computers on without tripping it, and the fan running along with the two monitors and printers it was only drawing 4.8 amps.

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Old 03-14-11, 10:01 AM
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remove any surge protection and see if the problem persists.

I wouldnt replace the breaker. Sounds like its doing its job
Old 03-14-11, 10:30 AM
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Hi Danny,

We have already tried the surge protectors. Removing them did decrease the consistency a small amount but they are still consistently tripping the breaker 8-9 times out of 10 when turning on any of the computers. If it was just one computer I would probably think it was a faulty PSU but with 3 computers all having the same effect I find that hard to believe. I've been reading online that computers are some what prone to tripping the AFCI's but apparently the newer generation AFCI's are supposed to be a little less problematic. I am guessing these are an older design as the house was built in 2004.
Old 03-14-11, 01:07 PM
Join Date: Feb 2011
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The fans in computers are brushless 12 volt DC fans so I doubt they are causing the problem. Try running the computers on a different AFI circuit if you have one and see what happens. If they run fine on another AFI then replace the problematic AFI breaker.
Old 03-14-11, 01:15 PM
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I agree that based on the age of the AFCI breakers they may be a first-generation design. Several manufacturers had recalls and redesigns at that time, so replacement of the troublesome AFCI breakers with new ones would be my first guess. Many of the mfrs have an AFCI feedback line you could let them know about the incompatibility. Perhaps your old breakers may be replaced under a recall or warranty.
Old 03-14-11, 06:10 PM
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With the 2008 NEC there are more and more AFCI breakers being used in new homes. I fear we'll be seeing more of these problems as new housing continues to pick up.
Old 03-14-11, 06:38 PM
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Haven't installed a lot of these but the only problem I had it detected a poor connection at the breaker. A UL rep says they were designed to look at the arc signatures of common appliances and ignore them as a properly functioning device.
Old 03-14-11, 08:33 PM
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Computer power supplies are loaded with mov's.
Old 03-15-11, 09:39 AM
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Just to let everyone know and in case someone runs into the same problem and is having issues replacing the AFCI breaker fixed the problem. I was hesitant to replace it without knowing for sure because the best price I could find was 49.99 and I hate to spend $50 on something without knowing it would fix it but I bit the bullet and picked one up and the problem has gone away.
Old 03-15-11, 09:45 AM
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Excellent. Thanks for letting us know.

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