AFCI Question

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aarsam

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Any help would be greatly appreciated.

I have an 15 amp AFCI circuit I'm having problems with.
-Breaker Cutler Hammer BR Combination AFCI
-6 Outlets 2 Lights (Same switch)

xxxxxx |-----Light
xxxxxx |
Panel----Switch---Light
xxxxxx |
xxxxxx |-----Outlet----Outlet
xxxxxxxxxxxx |
xxxxxxxxxxxx |----Outlet----Outlet---Outlet----Outlet

Situation
-My PC is plugged into an outlet for about 2 hours and the Breaker trips.
-I flip the breaker and try to restart the PC and it immediately trips.
-After an hour or 2 passes, I replug in the PC and it works again for about 2 hours then trips the breaker.
-tried a different breaker
-non motor loads are just fine
-vacuum trips the breaker immediately
-the pc trips the same style breaker on a different circuit immediately.
 
You may have a few issues here, first is you may have an overloaded circuit and it may not be the AFCI.
Second is you may have a nicked wire that does have an arc fault on it.
Third and most likely is the computer is acting like a capacitor and the AFCI sees it as a fault, and the same with the vacuum, is this computer by any chance a "Mac" tower ?
 
Aarsam, welcome to the forum. I see that you are an engineer but not directly tied to the electrical trades so I must ask we keep this to a discussion of why / what may be causing the problem, not how to change wiring, devices, breakers, etc...

Thanks

Roger
 
Do all the lights etc work fine without the computer or vacuum? Vacuum's used to wreak havoc on arc faults but I thought those issues were resolved. Perhaps not with the combo units.

I would leave a clock and lights on for a few hours - no pc and no motors and see what happens. It appears the pc and vacuum are causing the problem. Call Cutler Hammer. Also try the older arc faults- none combo unit and see what happens.
 
acrwc10
The only devices drawing current from the circuit is a PC and light fixture.
Nicked wire would make sense but would like to investigate that last as that will be the hardest to troubleshoot.
The PC is a Dell Studio Hybrid.
Roger
Thank you for the add.
We'll be sure to keep this discussion about troubleshooting and not a how to manual.
Dennis
The lights work fine without the PC or vacuum.
I have left the lights and a radio on for a few days and have had no issues.
I do have an older Arc Fault breaker (Non Combination) in my panel on a different circuit I'll switch the breakers and see if the issue is tied to the breaker. (Nice suggestion!)

Side notes
I plugged and vacuum into a GFCI protected outlet on a different circuit and no issues were found.
I plugged the vacuum into an older Non Combination Arc Fault breaker and no issues were found.

Next steps
switch older non-combination arc fault breaker to circuit in question to determine if the problem is indeed the breaker. I'll post back the solution. Thanks for your help!
 
Wasn't expecting this.....

I switched the Old non-combination arc fault and place it on the circuit in question and put the combination breaker in the place where the old non-combination breaker was.

Results..
Vacuum worked on both circuits.

So I guess the question is what is the difference between a non-combination and combination arc fault breaker and how does this impact my circuit?
 
aarsam said:
Wasn't expecting this.....

I switched the Old non-combination arc fault and place it on the circuit in question and put the combination breaker in the place where the old non-combination breaker was.

Results..
Vacuum worked on both circuits.

So I guess the question is what is the difference between a non-combination and combination arc fault breaker and how does this impact my circuit?
Click to expand...

A non combo unit only dealt with parallel arc faults while the new combo units deal with both series and parallel faults.

Here is an article that explains some of this
 
My guess is there is something in your circuit that isn't quite right. I would be curious if you switch it back to the original configuration if the problem comes back.
 
Switched the breakers back to their original configuration and the problem went away.

not sure why this is other then the obvious connection to the breaker was probably not solid enough.

I appreciate everyones ideas and all of your help!
 
Are you sure you kept the various branch circuit grounded conductors with their respective ungrounded conductors on the breakers?

Maybe they got mixed up to begin with, and in the process of changing them they ended up getting wired correctly.
 
aarsam said:
Switched the breakers back to their original configuration and the problem went away.

not sure why this is other then the obvious connection to the breaker was probably not solid enough.

I appreciate everyones ideas and all of your help!
Click to expand...

Don't be so sure the problem is gone until it is gone for a while.
If it is a nick in the wire it is common for a nick in a wire to be right at the panel box or outlet box, this happens when the wire is stripped, by moving it around you may have cleared the nick from touching anything.
 
acrwc10

You're right it's not fixed! Everything including the vacuum worked just fine last night. I got up this morning and my vacuum tripped the circuit again!

I called Cutler Hammer and they said they're is a known issue in my geographic location (Fargo, ND). After hearing the solution I can't imagine how much this issue has cost our local electrical contractors.

According to the engineer I spoke with on the phone there is a local radio station near my house that transmits a 1 MHz signal that causes problems with the Combination breakers. He said the Romex in the walls acts like an antenna properly tuned to the MHz frequency and that is the frequency the Combination breakers receives to determine a trip. When the signal amplitude (load + Radio station) was high enough it would confuse my breakers and trip them. They're sending me out a filter to correct the problem. It will be interesting if it works.

He also said the circuitry is different in the older non-combo arc fault breakers then the newer combination breakers, so only the new style is affected which would explain why I haven't had problems with the other non-combination style.

More importantly, he told me they have identified 3 areas in the country where this has been reported and the breaker is being re-engineered to avoid future problems like this. I would never have came up with this and am glad I called.
 
aarsam said:
acrwc10

You're right it's not fixed! Everything including the vacuum worked just fine last night. I got up this morning and my vacuum tripped the circuit again!

I called Cutler Hammer and they said they're is a known issue in my geographic location (Fargo, ND). After hearing the solution I can't imagine how much this issue has cost our local electrical contractors.

According to the engineer I spoke with on the phone there is a local radio station near my house that transmits a 1 MHz signal that causes problems with the Combination breakers. He said the Romex in the walls acts like an antenna properly tuned to the MHz frequency and that is the frequency the Combination breakers receives to determine a trip. When the signal amplitude (load + Radio station) was high enough it would confuse my breakers and trip them. They're sending me out a filter to correct the problem. It will be interesting if it works.

He also said the circuitry is different in the older non-combo arc fault breakers then the newer combination breakers, so only the new style is affected which would explain why I haven't had problems with the other non-combination style.

More importantly, he told me they have identified 3 areas in the country where this has been reported and the breaker is being re-engineered to avoid future problems like this. I would never have came up with this and am glad I called.
Click to expand...


Anyone want to write up a proposal for the next Code cycle to eliminate radio stations? :grin:
 
aarsam said:
acrwc10

You're right it's not fixed! Everything including the vacuum worked just fine last night. I got up this morning and my vacuum tripped the circuit again!

I called Cutler Hammer and they said they're is a known issue in my geographic location (Fargo, ND). After hearing the solution I can't imagine how much this issue has cost our local electrical contractors.

According to the engineer I spoke with on the phone there is a local radio station near my house that transmits a 1 MHz signal that causes problems with the Combination breakers. He said the Romex in the walls acts like an antenna properly tuned to the MHz frequency and that is the frequency the Combination breakers receives to determine a trip. When the signal amplitude (load + Radio station) was high enough it would confuse my breakers and trip them. They're sending me out a filter to correct the problem. It will be interesting if it works.

He also said the circuitry is different in the older non-combo arc fault breakers then the newer combination breakers, so only the new style is affected which would explain why I haven't had problems with the other non-combination style.

More importantly, he told me they have identified 3 areas in the country where this has been reported and the breaker is being re-engineered to avoid future problems like this. I would never have came up with this and am glad I called.
Click to expand...

That is very interesting aarsam,
Too bad you cannot easily substitute a Siemens or Square D combo breaker in its place. I have been testing a Square D combo breaker and I do not believe that it would trip under such circumstances.
Sounds like Cutler Hammer did not do their homework.
 
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