Combination AFCI/GFCI Circuit Breakers?

snipped-for-privacy@aol.com wrote:


I dug out some notes and reread a couple sources. The sources are: http://www.cpsc.gov/volstd/afci/AFCIFireTechnology.pdf http://www.iaei.org/subscriber/magazine/03_a/magazine_03_gregmanche.htm
UL did a survey of 1590 residential receptacles. 75A short circuit current was available at the end of 6 foot of #18 cord plugged into all (or almost all) the receptacles. A parallel arc, wire-towire, uses the available fault current but may not peak to quite 75A. AFCIs out there now should detect most parallel arcs in cord sets.
Series arcs should be able to be detected at a 5A arc level. (Sounds like a major challenge.)
Branch/Feeder AFCI Required for bedrooms in the 2002 NEC. Install as a circuit breaker (or at the panel) and detects arcs on branch circuits and feeders. They also detect arcs on cord sets plugged into a receptacle. The arc detection is at the 75A level so it detects parallel arcs. But there is also a test for "carbonized path" series arc on Romex. Since Romex has a ground wire, I believe this is found by the ground fault detection, which IIRC is required to be 50mA but is commonly 30 mA. If the arc was H-N, it would fairly rapidly also become a ground fault. (UL did limited tests of "glowing connection" series arcs on grounding type receptacles, and about half eventually tripped an AFCI from the ground fault current that developed.)
Outlet circuit AFCI Installs as a receptacle and may have wire through (like a GFCI receptacle). Arc detection is at the 5A level, so they will detect series and parallel arcs. Can detect upstream series arcs.
Combination AFCI The 2005 NEC requires all AFCIs installed after 1-1-08 to be Combination type. Installs as a circuit breaker and combines the protection of Branch/Feeder and Outlet Circuit. Will detect series arcs.
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Thank you for the excellent references. (I guess I am going to renew my IAEI membership again.) The IAEI article was excellent. There are a lot of rumours and misinformation about AFCI's and it is going to take some convincing arguments to convince people the 2008 NEC is correct.
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Gerald Newton wrote:

I don't remember if it was obvious, but the IAEI article has 3 parts.
http://www.iaei.org/subscriber/magazine/03_b/magazine_03b_gregmanche.htm Part 2 is on AFCI installation and troubleshooting
http://www.iaei.org/subscriber/magazine/03_d/magazine_03d_gregory.htm Part 3 is less interesting; information includes discussion on AFCIs in the 2005 NEC

There are 3 posters in this thread (including me) that think the 2008 NEC is wrong.
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Charles Perry wrote:

I think they are mostly 30 ma.

Interesting. Why would the AFCI/GFCI was slower. A new topic of investigation for EPRI.
As you probably know, a GFCI includes a function that detects downstream N-G shorts with no load. When an AFCI has a load there will be a voltage drop that can produce the N-G fault current to trip the AFCI.
[Are you suggesting the code should add 'wife malice' protection? An exciting new field.]

IMHO it would have been appropriate for the extension of AFCIs beyond the previous bedrooms to be based on the record of the AFCIs already installed in bedrooms. It wasn't.
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Keep in mind that we tested using a single make/model of each type. We did test multiple units of the same make/model of the combo unit just to make sure we were seeing what we thought we were seeing. We also done some testing of tripping of AFCI breakers due to EMI/EMC problems. Just think, your neighbor installs a new heat pump with an adjustable speed drive and your breakers starts tripping. Could happen. I know they say the filtering is great, etc but we make a living cleaning up after things that don't exactly work as predicted.
Now if I could just get several utilities to fund some AFCI testing work ;-)

Hahaha. I have to be careful what I say right now. I am recovering from ACL reconstruction (replacement actually) surgery that happend one week ago today. I am VERY dependant on my wonderful spouse (she might be reading over my shoulder) during this recovery!

Agreed. It was based on undue influence by those with GREED. IMO of course.
Charles
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