AFCI BREAKER PROBLEM - NEED CONFIRMATION.

[ramsy]

This is a troubleshooting method, only; not an AHJ approval method.

Now I see, control power comes from equipment bus thru breaker to neutral or pigtail. No Hot (Load) wire needed.

 

[LarryFine]

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Note the round yellow sticker. The OP confirmed this fed from a 208Y/120v service.

 

[mopowr steve]

So does Sq D offer a 2pole AFCI or GFCI that will operate on a 120/208 Y system?

 

[al hildenbrand]

So does Sq D offer a 2pole AFCI or GFCI that will operate on a 120/208 Y system?

Your question got me curious. Click here for the Schneider Electric Catalog section. Go to page 1-12. All they show, in the two pole AFCI is limited by footnote 16. 120/240 single phase only. No 208Y/120 allowed.

So, no.

 

[ritelec]

Note the round yellow sticker. The OP confirmed this fed from a 208Y/120v service.

What if you remove the yellow sticker?

 

[LarryFine]

What if you remove the yellow sticker?

The magic smoke comes out.

 

[ramsy]

Your question got me curious. Click here for the Schneider Electric Catalog section. Go to page 1-12. All they show, in the two pole AFCI is limited by footnote 16. 120/240 single phase only. No 208Y/120 allowed.

Unbelievable - SQ-D is incompatible with MWBC's in all 208Y/120 residential sectors.

Page 12, footnote 16 for QO. Page 22, footnote 5 for HOM.

 

[mopowr steve]

Interesting!
how are people handling this when an apartment complex service is fed by a 3phase 208/120 Y system but then individual units are fed only diversified single phase 120/208?

 

[retirede]

Interesting!
how are people handling this when an apartment complex service is fed by a 3phase 208/120 Y system but then individual units are fed only diversified single phase 120/208?

GE equipment?

 

[Cybatrex]

So does Sq D offer a 2pole AFCI or GFCI that will operate on a 120/208 Y system?

They do not. I spent much time on the phone.


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[augie47]

What if you remove the yellow sticker?

The magic smoke comes out.

 

[Sierrasparky]

Id see if the panel can is the same dimensions of the Sq d, remove all the sqD and replace with GE guts and cover.

Or cut in some afci dead front receptacles fed with one on the approved methods.

 

[al hildenbrand]

Interesting!
how are people handling this when an apartment complex service is fed by a 3phase 208/120 Y system but then individual units are fed only diversified single phase 120/208?

There is one way to handle these existing multiwire branch circuits (short of refeeding them as a pair of two-wire branch circuits). Add a GE suppanel and handle tie a pair of single pole CAFCIs. You see, GE is the only CAFCI that does not require the LOAD neutral to be connected to the load terminal of the breaker. The GE CAFCI is purely arc fault sensing without any ground fault sensing component.

The problem, in a single phase panel, like that shown in the OP, is that the neutral current is not the arithmetic sum of the difference between L1 and L2 (the two hot phase leg currents.) Rather the neutral current is the result of the vector sum of two currents at 120 degrees of each other.

All AFCIs, except those made by GE, have a ground fault sensing component. So, Square D, Siemens, and Eaton AFCIs will all trip because the ground fault sensing component in them will be triggered.

So, handle-tied single-pole GE CAFCI breakers will work with an existing MWBC. The alternative is to refeed the MWBC with two two-wire branch circuits thus removing the shared neutral.

 

[wwhitney]

The problem, in a single phase panel, like that shown in the OP, is that the neutral current is not the arithmetic sum of the difference between L1 and L2 (the two hot phase leg currents.) Rather the neutral current is the result of the vector sum of two currents at 120 degrees of each other.

All AFCIs, except those made by GE, have a ground fault sensing component. So, Square D, Siemens, and Eaton AFCIs will all trip because the ground fault sensing component in them will be triggered.

I'm having a little trouble with this explanation. Won't the GF component of the AFCI simply pass all three conductors (L1, L2, and N) through a toroid to detect any instantaneous current imbalances? That will be the equivalent of doing the vector sum you describe.

I would think the limitation arises from the AFCI side of things (which is a black box), rather than from the GFCI side of things. Won't a standard 2 pole GFCI breaker work properly on a 120/208 3-wire circuit?

Cheers, Wayne

 

[al hildenbrand]

I'm having a little trouble with this explanation. Won't the GF component of the AFCI simply pass all three conductors (L1, L2, and N) through a toroid to detect any instantaneous current imbalances? That will be the equivalent of doing the vector sum you describe.

Thank you Wayne, you are correct. My explanation about the ground fault sensing component in the AFCI being to blame is wrong.

I would think the limitation arises from the AFCI side of things (which is a black box), rather than from the GFCI side of things.

I agree that the "black box" is where the incompatibility has to be coming from.

Won't a standard 2 pole GFCI breaker work properly on a 120/208 3-wire circuit?

Yes.

 

[kwired]

Interesting!
how are people handling this when an apartment complex service is fed by a 3phase 208/120 Y system but then individual units are fed only diversified single phase 120/208?

by not using MWBC's for any circuits requiring AFCI protection. Singe pole AFCI's will still work on these systems.

 

[brantmacga]

by not using MWBC's for any circuits requiring AFCI protection. Singe pole AFCI's will still work on these systems.

That. And i can’t remember the last time I worked on or bid an apartment complex that was 208Y/120. It’s not a popular setup in the south.


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[chris1971]

Florida now uses 2014 NEC which introduced a series of pain in the but situations with AFCI Breakers. Good luck when trying to find a 2 PULL CAFCI breaker.

Q: 2 - 20A 2P CAFCI breakers I installed are both not tripping with the test button when pressed. It seems odd that both of them are doing it. When the test button doesn’t work but the breaker trips during an ARC the breaker is defective, correct? If you have any suggestions that I can learn from, I’m all ears.

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2 pole AFCI circuit breakers are available for most if not all current electrical panels. You probably defective two pole breakers. What brand are you using?

 

[Sierrasparky]

2 pole AFCI circuit breakers are available for most if not all current electrical panels. You probably defective two pole breakers. What brand are you using?

No defective components here, SQD wont work on a multiwire circuit fed by a 3phase wye system.

See the sticker on the breaker NO 208!

 

[kwired]

That. And i can’t remember the last time I worked on or bid an apartment complex that was 208Y/120. It’s not a popular setup in the south.


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Get big enough complex and it kind of becomes necessary.

2 pole AFCI circuit breakers are available for most if not all current electrical panels. You probably defective two pole breakers. What brand are you using?

You copied the pictures and still can't tell which brand they are??