brycenesbitt
Senior Member
- Location
- United States
There's a lot of bad press on AFCI on this forum, I though I'd share a semi-success story:
In a 1930's construction home a double-pole AFCI was added the legacy multiwire shared neutral Knob & Tube circuit. The AFCI trips immediately, and the sparky replaces it with a regular breaker. But on second look two things are found:
1) Plumbers added a circuit, and managed to wire nut in both sides of an unused 24 volt doorbell wire. This 24 volt wire then sat in the basement just waiting to spark.
2) One K&T neutral is interconnected to a modern breaker neutral. And of course it's all done wrong. The bad wiring then goes and actually sparks.
Thus the AFCI lead to the discovery of two sparking wire segments. Sort of.
Once the faults are cleared the original AFCI was reinstalled, and worked fine with no callback.
----
Without disagreeing with much of the bad AFCI sentiment, I can see the merit of AFCI for knob & tube, given the way wires enter metal junction boxes. Some vendors seem to agree "Eaton recommends the use AFCI in older homes with knob and tube wiring systems. Contact Eaton's Residential Application Team for assistance".
Those complaining of AFCI false trips perhaps could submit reports to: http://afcisafety.org/report.html
In a 1930's construction home a double-pole AFCI was added the legacy multiwire shared neutral Knob & Tube circuit. The AFCI trips immediately, and the sparky replaces it with a regular breaker. But on second look two things are found:
1) Plumbers added a circuit, and managed to wire nut in both sides of an unused 24 volt doorbell wire. This 24 volt wire then sat in the basement just waiting to spark.
2) One K&T neutral is interconnected to a modern breaker neutral. And of course it's all done wrong. The bad wiring then goes and actually sparks.
Thus the AFCI lead to the discovery of two sparking wire segments. Sort of.
Once the faults are cleared the original AFCI was reinstalled, and worked fine with no callback.
----
Without disagreeing with much of the bad AFCI sentiment, I can see the merit of AFCI for knob & tube, given the way wires enter metal junction boxes. Some vendors seem to agree "Eaton recommends the use AFCI in older homes with knob and tube wiring systems. Contact Eaton's Residential Application Team for assistance".
Those complaining of AFCI false trips perhaps could submit reports to: http://afcisafety.org/report.html