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QO Plug-on Neutral CAFCI/GFCI Circuit Breakers

Merry Christmas
busman

busman

Senior Member
Location
Northern Virginia
Occupation
Master Electrician / Electrical Engineer
busman said:
Unless the arcs that are being artificially generated by this test setup are not representative of real world loose connection arcs, I believe there is some scientific substantiation that AFCI's can operate as designed. With that said, I'm not at all convinced that they are great; they probably miss a large number of arc types and declare things that are not arc to be such.


Mark
Click to expand...
My apologies. I missed that this paper is all DC circuits. I'll keep looking for AC reports.

Mark
 
R

ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
busman said:
there is some scientific substantiation that AFCI's can operate as designed
Click to expand...
Yes as tested to UL 1699/B, but empirically not to UL 489, since test buttons fail in the energized position.

There is no provision in UL 489 to shift liability on consumers who fail to exercise Test buttons once a month, per NEC 110.3(B).

UL 489 devices open automatically once overload and short circuits occur, to protect wires and cables.

There is no exception for xFCI circuit breakers, regardless of working out of the box for a few months.

Unlike xFCI outlet devices, perhaps shielded behind the impedance of branch wire, reset-button electronics installed in fuse boxes historically fail in the field, and any UL 486 certification should be revoked Per OSHA requirements.
 
ActionDave

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
busman said:
Unless the arcs that are being artificially generated by this test setup are not representative of real world loose connection arcs, I believe there is some scientific substantiation that AFCI's can operate as designed. With that said, I'm not at all convinced that they are great; they probably miss a large number of arc types and declare things that are not arc to be such.


Mark
Click to expand...
I spent a whole day troubleshooting a tripping AFCI breaker on a new home. I could run my old beat up skil saw with a commutator and brushes so worn out that it would throw out a blue flame big enough to be seen in full sunlight but would not trip the AFCI, but a brand new Hitachi and Makita chop saw would. Plug any of the three into a GFCI protected circuit and there was no problem. Both of the chop saws had fancy soft starts on them.

Different project, different brand breaker, Bosch router with a soft start would trip AFCI breakers all over the house, non of the other power tools on the job did. Later, after the home owners moved in I had to go back and troubleshoot because the big screen tv would trip the AFCI breaker it was on. That was in the early 00s

Sometimes around 2019 I visit my inlaws and their new refrigerator would trip the dual function GFCI/AFCI randomly. It was on a dedicated circuit so we put in a straight GFCI breaker, hasn't tripped since.

It's not motors that trip AFCIs and it's not arcs, it's electronics, most likely SMPS that do it. The only thing I've not seen them trip on is an actual arc. My evidence is anecdotal but there have been studies showing they don't trip on a glowing connection which is what causes electrical fires and 120V won't sustain an arc the same way 480V does.

AFCIs are a fraud.
 
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