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Fixing overly-sensitive AFCI circuit breaker? (not GFCI!)

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  • Sep 1st, 2008 9:47 am
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Fixing overly-sensitive AFCI circuit breaker? (not GFCI!)

Every since I moved into my condo 4 years ago, I have had a circuit with a GFCI breaker that seems overly sensitive.

Because of the commendable wiring job by Torbel's contractors, the plugs in both my bathrooms as well as along the outside walls of both bedroom are all on a common circuit, protected by a GFCI breaker. because of this, all my computer and AV equipment is plugged into this circuit.

The problem I'm having is that almost randomly, the breaker trips, cutting power to the circuit. For about a year it had stopped (only happened every 2-3 months) but now it's back to 4-5 times a week. Very often it happens 6-8am, so I'm thinking it could be related to voltage fluctuations from the grid.

Is this normal behaviour? Is it possible the GFCI breaker is defective or too sensitive? Any suggestions on what I can do to troubleshoot this? Aside from that all the equipment on the circuit is operating normally. It's getting annoying to come back home from work and find all my equipment off and UPSes drained..
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Deal Addict
Jan 11, 2007
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I would spend $15 on a new GFI and if the same thing happens then you explore what is making it trip.
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Mar 21, 2006
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The bedroom outlets should be on Arc fault breakers at the panel. The bathrooms should be on a GFCI outlet common to all the bathrooms, or a GFCI breaker at the panel.

Arc fault breakers are sensitive to high power equipment starting up quickly.

Perhaps there is something else that comes on and causes a fast inrush and trips it.
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BuildingHomes wrote:
Aug 30th, 2008 7:38 pm
The bedroom outlets should be on Arc fault breakers at the panel. The bathrooms should be on a GFCI outlet common to all the bathrooms, or a GFCI breaker at the panel.

Arc fault breakers are sensitive to high power equipment starting up quickly.

Perhaps there is something else that comes on and causes a fast inrush and
trips it.
You are correct... I just double-checked the breaker and it's an AFCI breaker, not GFCI.

The situation is that the bathroom fans, lights, and plugs, as well as 6 plugs within the bedrooms, are all on a single circuit protected by an AFCI breaker at the panel. There are no GFCI outlets anywhere in the circuit, just the breaker.

There is no sudden-surge equipment on the circuit at all, when it trips in the morning or anytime. I'm wondering of the UPSes (I have two of them plugged in) somehow send some sort of weird phase back down the circuit or something.
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Aug 2, 2008
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hoob wrote:
Aug 30th, 2008 7:56 pm
You are correct... I just double-checked the breaker and it's an AFCI breaker, not GFCI.

The situation is that the bathroom fans, lights, and plugs, as well as 6 plugs within the bedrooms, are all on a single circuit protected by an AFCI breaker at the panel. There are no GFCI outlets anywhere in the circuit, just the breaker.

There is no sudden-surge equipment on the circuit at all, when it trips in the morning or anytime. I'm wondering of the UPSes (I have two of them plugged in) somehow send some sort of weird phase back down the circuit or something.
I wonder if you can do :
Main Panel with AFCI -> Sub-panel with only 1 GFI -> Circuit
Then you'd have Arc fault and ground fault protection on the same circuit... but would it be allowed as per code?
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hoob wrote:
Aug 30th, 2008 7:56 pm
.... I'm wondering of the UPSes (I have two of them plugged in) somehow send some sort of weird phase back down the circuit or something...
+1, some models of UPS (like APC) do a periodic self test to check the battery. What might be happening is when the self test runs, everything connected to the UPS goes off AC load and onto the battery. When the test ends a few seconds later, everything goes off battery load and back onto main AC.

This is equivalent to turning everything connected to the UPS "off" and then back "on" at the same time.
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Kitchener
I just replaced an AFCI for someone because everytime he turned on his computer it would trip. His panel has some of the older ACFI's that were too sensitive. The ACFI are about $80 at Home Depot, works great now
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Drthorne wrote:
Aug 31st, 2008 9:57 am
I just replaced an AFCI for someone because everytime he turned on his computer it would trip. His panel has some of the older ACFI's that were too sensitive. The ACFI are about $80 at Home Depot, works great now
I actually had a PC once (a friend's that I was repairing) that, by itself, when turned on would trip my AFCI breaker. So that's promising symptom of the cause.

How hard is it to replace them? Can they be replaced "hot" (I'm not sure if my panel has whole-unit breaker in it, not sure I want to get a building electrician to shut down the unit centrally or something, $$$.)

This unit is 2004, not very old, but... *shrug*..
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hoob wrote:
Aug 31st, 2008 5:02 pm
How hard is it to replace them? Can they be replaced "hot" (I'm not sure if my panel has whole-unit breaker in it, not sure I want to get a building electrician to shut down the unit centrally or something, $$$.)
Eh? There should be a main breaker for your panel, right on your panel. Turn it off. Make the adjustment. Check your wiring. Turn it back on.
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BuildingHomes wrote:
Aug 31st, 2008 5:11 pm
Eh? There should be a main breaker for your panel, right on your panel. Turn it off. Make the adjustment. Check your wiring. Turn it back on.
Nope, there's some main apartment breaker somewhere in the building, but not inside my unit. I will have to ask the property manager...

Image
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hoob wrote:
Aug 31st, 2008 5:27 pm
Nope, there's some main apartment breaker somewhere in the building, but not inside my unit. I will have to ask the property manager..
That botheres me.

Every appartment I have ever had has had one.
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hoob wrote:
Aug 31st, 2008 5:27 pm
Nope, there's some main apartment breaker somewhere in the building, but not inside my unit. I will have to ask the property manager...
looks illegal to me, I'm pretty sure code requires a main disconnect 9 metres from any subpanel and within sight while standing at the panel
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