AFCI troubleshooting (really weird!!!)

[DustyGmt]

Hello all, new poster, new to the trade so please forgive me if I'm not giving complete and adequately precise information but my boss and I encountered a pretty strange situation today and I will outline the information below to the best of my ability and see if you guys have any idea as to what could cause this.

Went to a house, lady has a 120/208 panel. She had a 15a AFCI breaker on one phase and a regular single pole breaker for a washing machine on the other phase.

The 15A AFCI breaker protected the living room outlets and the regular single pole breaker protects the washing machine. Separate circuits, separate phases, one having nothing to do with the other and yet when the washing machine would finish filling and as soon as the motor kicked on this would cause the 15A AFCI protecting the living room circuit to trip. Here is the other weird thing, the circuit would only trip if the TV was on. The AFCI would not trip if the TV was on but an arc would still register on the diagnostic meter.

We put an AFCI diagnostic device on the AFCI breaker and it ruled out a ground fault, it only told us that it was indeed an arc fault but the fact that these circuits were totally separated and on different phases has me really confused. Our meter readings seem normal also.

Any thoughts?

 

[mopowr steve]

I’ve posted here before that I had a plasma screen tv show up as an arc fault with my diagnostic tester that affected arc fault breakers not of that circuit or phase.

Make sure your using the latest revision of breaker. Manufacturers have diagrams on how to read serial numbers to determine manufacture dates.

You may want to have the neutral checked though to make sure it’s not compromised somewhere.

 

[al hildenbrand]

Welcome to the Forum ! !

Good description. May I ask for some more detail?

You say the service is 120 / 208. . . so the service is two 120 Volt phase legs of a four wire 208 Y / 120 Volt three phase supply from the Power Company?

It sounds like you have a Siemens Intelli-Arc Fault Diagnostic Tool to work with, am I right?

Is the AFCI breaker a Branch-Feeder or a Combination Type, and who manufactures it? (Eaton, SqD, GE, Siemens)

And, the neutral for each of these circuits is a separate conductor (not a shared "multiwire" neutral)?

 

[DustyGmt]

I’ve posted here before that I had a plasma screen tv show up as an arc fault with my diagnostic tester that affected arc fault breakers not of that circuit or phase.

Make sure your using the latest revision of breaker. Manufacturers have diagrams on how to read serial numbers to determine manufacture dates.

You may want to have the neutral checked though to make sure it’s not compromised somewhere.

Thanks for the info. We were considering a problem with the neutral somewhere. Is it possible for an arc fault to detect a problem ahead of the panel? Just wondering

 

[DustyGmt]

Welcome to the Forum ! !

Good description. May I ask for some more detail?

You say the service is 120 / 208. . . so the service is two 120 Volt phase legs of a four wire 208 Y / 120 Volt three phase supply from the Power Company?

It sounds like you have a Siemens Intelli-Arc Fault Diagnostic Tool to work with, am I right?

Is the AFCI breaker a Branch-Feeder or a Combination Type, and who manufactures it? (Eaton, SqD, GE, Siemens)

And, the neutral for each of these circuits is a separate conductor (not a shared "multiwire" neutral)?

Yes I am pretty sure you are correct, N for each circuit is separate conductor and not shared. Also I am pretty sure your are right on the power supply configuration and brand/model of the AFCI breaker I'm going to consult my boss in the morning to make sure i got all this info correct and he may be able to add to the equation with info I cannot. I appreciate the help thus far tho....

 

[mopowr steve]

Thanks for the info. We were considering a problem with the neutral somewhere. Is it possible for an arc fault to detect a problem ahead of the panel? Just wondering

where transients occur from within the premis or from outside it’s influences on arc fault breakers are a crap shoot to figure out.

 

[al hildenbrand]

. . . and brand/model of the AFCI breaker I'm going to consult my boss . . .

Thanks. I'll be interested to know.

Each of the AFCI manufacturers have highly secret and proprietary solutions to the "Grand Concept" of "AFCI". As a result, they have some differences that are unique. Perhaps the most strikingly different AFCI is the current Combination-Type models made by GE.

 

[hbiss]

where transients occur from within the premis or from outside it’s influences on arc fault breakers are a crap shoot to figure out.

Right. What the OP thinks is a weird problem really isn't. Since he is an apprentice, I don't expect he has all the facts about AFCIs or a lot of experience with them, just what he may have read or been taught. There are only three things an AFCI will do: operate as a normal OCPD, nuisance trip and make money for the manufacturers.

-Hal

 

[romex jockey]

Just a thought passed along here....DustyGmt........a possible diagnostic that may/may not reveal the culprit.

De energize the panel in question

Isolate every nuetral from the MBJ

Ring them all out individually to ground

~RJ~

 

[growler]

I’ve posted here before that I had a plasma screen tv show up as an arc fault with my diagnostic tester that affected arc fault breakers not of that circuit or phase.

Make sure your using the latest revision of breaker. Manufacturers have diagrams on how to read serial numbers to determine manufacture dates.

You may want to have the neutral checked though to make sure it’s not compromised somewhere.

Yes, I have had better luck just changing out the breakers for newer versions than anything else. The only way you will ever know if you have a bad AFCI is to swap it out for a later version.

 

[growler]

There are only three things an AFCI will do: operate as a normal OCPD, nuisance trip and make money for the manufacturers.

-Hal

You could be right. I have not been finding real problems with the wiring the way I thought I would. When GFCIs were introduced I would find real problems with the building wiring that would not show up with regular breakers.

Not long ago I had an AFCI that would trip intermittently and I did find what I thought were real wiring problems and I repaired them but the breaker kept tripping so I changed the breaker for a new one and everything works as normal.

 

[romex jockey]

Just a thought passed along here....DustyGmt........a possible diagnostic that may/may not reveal the culprit.

De energize the panel in question

Isolate every nuetral from the MBJ

Ring them all out individually to ground

~RJ~

forgot to add, ring them all out individually to each other as well

~RJ~

 

[steve66]

There are only three things an AFCI will do: operate as a normal OCPD, nuisance trip and make money for the manufacturers.

-Hal

Really? Your going to blame the AFCI and the manufacturer's that pushed these?

As if people should just take it for granted that they can do their laundry and watch TV at the same time!!