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AFCI trip when computer turns on

19K views 61 replies 12 participants last post by  rolfcm106 
#1 ·
New home that is about 4 years old. Just moved into it. My Mac trips this AFCI breaker when i turn it on. Never happened in the older home. These AFCI are all in the bedrooms. If i plug the computer into the living room, it does not trip the swtich. I even replaced the AFCI and it does the same thing. Can i just replace it without a AFCI? The AFCI has 3 wires where the regular 20 breakers have one line going to it. I understand the white wire doesnt need to be installed..but what about the red and black if I switch it to a regular breaker?
 
#2 ·
It sounds like you have a wiring problem. I would not replace the AFCI with a regular breaker until you investigate the wiring further.

They do make 2 pole AFCIs but they are rare and I doubt your builder used one for a simple bedroom circuit.

Posting pictures might be a good way to go, thanks.
 
#60 ·
I doubt its an afci problem.

Try different loads, like a space heater.

DO NOT replace the afci with a non afci, it violates the electrical code your house was wired under.

Maybe your psu is bad?

Red and black?

Please post pictures.
Most likely not the case, I have this exact same problem in my new apartement. My computer would trip the breaker when I turn it on. Swapped the power supply with a new one, still have the same problem. A quick fix is I bought a Battery Back up Uninteruptable Power Supply to replace the surge protector it was connected to, that was then plugged into the tripping outlet.
Doing exactly this, I plugged it into an outlet that it didnt trip. Plugged the computer into the Battery Back up UPS, let it charge over night. Turned the computer on and unplugged the UPS (beeping from UPS began to signal power has been cut / has gone out) then plugged it into the outlet that the computer was tripping. Turns on just fine now. The reason I did that was I think the particular motherboard I have starts up different or something when it has been unplugged vs when it is off but has been plugged in since it was powered off. i.e., a solid blue LED light will light up on the power LED (with the HDD LED not on or flashing) if you plug it in and have not powered it up. But once you power it on and turn it off. It will have no LED light at all while off. This is a custom built computer, and some premanufactured ones will power on by themselves when you plug them in even if you dont press the power button. I am referring to desktops only by the way. Not sure why this happens but I have come across it with system I have seen in for repair at work.

Hope my temporarely solution helps you out too.
 
#10 · (Edited)
Only if he runs the PC ungrounded, not a good idea because all PC SMPSs I've seen do leak a few ma current to ground.

It would need to be leaking 30ma+ to set off a regular AFCI though... That's dangerous levels.

I just looked and Mac Pros apparently can pull up to 12 amps too. 1000+ watts for a computer, heh. I doubt it's a straight load issue and would suspect ground current still, until proven otherwise.
 
#16 ·
Since the AFCI switch only trips a couple times a week, do you think its the computer power supply on the mac or would it trip all the time if it was that part?

Its a seiemens switch. Can i just change that to a reqular switch?
Do you have push in receptacles? (the wires are pushed into a hole instead of around the screw)

You can't swap the breaker out, it violates code and is a safety hazard.
 
#21 ·
The siemens part has 2 wires and a white wire. They push in. The other non AFCI just have 1 wire. I am bringing the computer in for a brand new power supply (350.00) OUCH. Hope that takes care of it. IF not, if put in a AFGI plug outlet, will that trip before the AFCI trips? I hate to keep running downstairs to flip the AFCI switch.
 
#22 ·
Make them pay for it, if the old one has high ground current it is defective, and a potential safety hazard. If you plug it into a GFCI then it should trip every time.

GFCI is not the same as AFCI. There is no such thing as an AFCI outlet that I'm aware of.
 
#25 ·
GFCI test



I did test it just now on a GFCI. Worked fine. First time i powered it up, the light in the bathroom dimmed. After that i turned it on and off..and it worked fine. BUT, then i brought it back into the bedroom and did it on and off again. It did not trip the AFCI switch. It does it occationally. SO, if it does it occationally is it the computer or is it the switch?
 
#26 ·
I did test it just now on a GFCI. Worked fine. First time i powered it up, the light in the bathroom dimmed. After that i turned it on and off..and it worked fine.
That means I was wrong and it's not excessive ground current. It's probably not an intermittent ground fault in your outlet, or it would happen while the computer was running too, not just when you first turn it on.

It could be the massive inrush when the capacitors first charge. It would have to last for 3 or 4 cycles cycles and pull around 50 amps to trip the AFCI though. Hmm...

I don't think replacing the power supply will help you.

If it were me, I'd put a regular breaker in my panel at this point, or relocate the computer to a different room that doesn't have an AFCI. Replacing the breaker with a standard breaker will violate code so no electrician will touch it. Replacing a breaker means working around electrically energized parts, even if you turn the main breaker off. If you don't feel comfortable doing the job then don't do it. And make sure to complain to Apple and the AFCI manufacturer (using that form that someone posted earlier) so they can sort out what's causing this.

I guess I owe Billy_Bob $5.
 
#27 ·
I guess I owe Billy_Bob $5.
No, I don't gamble and never agreed!

Anyway there are a couple of other things which might be interesting to try if you want.

One theory is that "arcing" of a switch or the sparking of the brushes in a motor (Or whatever) will cause this unwanted tripping of an AFCI.

So it has been suggested that a surge suppressor might keep the AFCI from seeing the arcing or some of this.

Also suggested that an isolation transformer might do the trick ($$).

I have not read if these work or not, so might want to borrow one first and give it a try.

Keep in mind that this may also defeat the intended purpose of the AFCI.
 
#28 ·
Seems like the AFCI is seeing the switching power supply as an arcing fault. I believe that AFCIs are junk and are as useless as tits on a boar. But I don't want to encourage anyone to violate the code in effect in their area, but wink wink nudge nudge... I know what I would do.
 
#31 ·
Can i put a GFCI plug in the bedroom? I have my computer plugged into the bathroom via an extention cord and it has not tripped at all. Will this solve the problem, or will this still trip the AFCI?
Well this confirms there's no significant ground fault current, and it really is an arc-fault false alarm from the heavy load when the caps charge.

A GFCI outlet in your bedroom would not satisfy the AFCI code requirements for your bedroom outlets. You are free to install a GFCI in your bedroom, but it does not provide the same type of protection an AFCI provides, and it will not stop the AFCI from tripping.

You could replace the AFCI with a regular breaker and violate the code. Just keep the AFCI and reinstall it if you ever go to sell the house. If your house burns down it's not my fault. All I can say is that millions of houses out there do just fine without AFCI breakers.
 
#32 ·
Do you have an APC (UPS) Unit? You know, one of them new-fangled boxes that keeps your computer going when the power fails? :huh:

I'd try using one of those, which could effectively limit the inrush current upon startup, as well as clean up surges/sags/spikes in your power supply.

This may solve your intermittent nuisance tripping problems as well ... :whistling2:
 
#34 ·
Most likely not. Modern home UPS systems pass through utility power mostly untouched* unless the voltage goes above or below the thresholds. As I doubt your inrush is dropping the voltage enough to trigger the UPS, it probably wouldn't help.


*Except for a low-pass filter for noise

That said, a UPS isn't a bad investment. Just make sure to get one that's at least 2000 volt-amps for a system as big as yours.
 
#39 ·
You can buy UPS systems that don't pass through current. They actually re-generate 60HZ sine wave. These are very, very expensive. For a system that requires 2,000KVA, you might pay upwards of $1,000US!
In any case, even a standard type UPS will protect very well against surges and noise, so it would perform at least as well as the surge protector in possibly eliminating stray noise that may be causing your problem.
 
#36 ·
No one really told me if i can put a GFCI plug in the bedroom.
You can.

Is it easy to put this in (2 wires like a regular outlet).
It's not much more difficult than a regular outlet. You need to decide if you want to protect downstream outlets or not.

Would this trip before the AFCI would trip.
No, because your problem isn't ground fault currents.
 
#40 ·
There is one way, but a very expensive and not very practical one which you could use to save yourself the time of going downstairs to reset the breaker, while probably still meeting code.

Run a 40A or 50A feeder up from a regular breaker in your main panel to the second floor (or wherever your computer is located), and re-wire your bedroom circuit to that new panel. Install the AFCI breakers in the sub-panel.
Now, you really need to have a licensed electrician to do this kind of work, and at least it must be inspected before use.

You're grinning painfully, and maybe laughing. This wasn't intended as a real solution, just something that would physically and electrically work.

The real solution is not to change anything in the wiring of your home. It is to change the problem in the computer.
Apple should be forced to come up with a fix, considering that many users are having this problem.
Have you tried contacting Apple?
 
#43 ·
Anyone have an update?

Okay, so I have moved in to a new house and tried to setup my PC in my den. The outlets are connected to an AFCI breaker on the main circuit board in the basement. The breaker is 15A - everytime I turn on my computer it trips the AFCI breaker, even if I plug only the computer in with nothing else and no accessories. I normally have the computer plugged in to a surge bar.

I tried plugging the computer in to another outlet (i.e. the bathroom GFCI) and it boots up fine. I have other devices, such as the modem, phone, router, monitors, etc. plugged in to a power bar connected to the den outlet. None of these devices are tripping the AFCI.

After searching on Google as to what the cause it, it seems like AFCI breakers don't get along with computers much. This is also how I found this forum. ;)

But so far, nothing helped.

I might be able to try changing the AFCI to a regular breaker, but I believe the bedroom outlets are connected to the two AFCI breakers too. But -changing to regular breakers would violate the building code. I currently have a Siemens AFCI with a blue test button.

I have a Enermax Liberty 500W power supply in my PC, it has Active PFC, but it still trips the breaker. I might try getting a new power supply for my PC, but not sure if it'll solve the problem.

Needless to say, this is annoying. :furious: Anyone have suggestions, especially those that are electricians? Maybe trying a different brand or newer AFCI breakers? Maybe try a 20A breaker? House is built 2004-2005, so it probably has one of the earlier versions of these AFCI breakers.

Thanks.
 
#46 ·
Like I said, I know what I would do...

But your best bet is to call the local inspector and explain the situation to him and see if he would be OK with you replacing the AFCI with a standard breaker. This would be the only code compliant way around the problem without buying expensive equipment. Ask for a variance. A Siemens breaker costs treefidy.
 
#47 ·
I started this posting and no real answer. I have it plugged into the bathroom GFCI. If the bedroom is a office can you really break the code since its not a bedroom by changing the breaker? Then put the breaker back in once it is a bedroom.

Can someone help me walk through the steps of changeing the Siemens 2 wire breaker to a 1 wire breaker? It has to be easy. I already took the breaker out and put it back in.
 
#53 ·
OK. This is better, thanks. Yes you don't need to touch any wires other than the one going into the breaker you are changing. You would turn the big breaker at the top off. Make sure you have a battery powered light to work by.

Then you would turn off the AFCI breaker you are replacing. Then disconnect the curly pigtail from the neutral bar... watch out if the wires are doubled-up... you don't want to leave any loose wires there. Disconnect the white and black from the AFCI breaker. Put the white wire where the pigtail was and tighten it down. Pull the old breaker out and save it for when you sell the house. :whistling2: Put the black wire into the new breaker, tighten the screw. Snap the new breaker into place. Turn on the new breaker and then the big main breaker.
 
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