tropical36 wrote:
DrewE wrote:
A couple years ago I disconnected and removed a couple of old electric heaters from the basement of my house as they were no longer useful (I had no need of heating the basement) and looked to me to be of questionable condition. The circuit, until I shut it off to remove them, had been live with no apparent troubles for many years.
Upon dismantling one, I discovered that an internal wire had broken and shorted against the metal case of the heater, burning a hole in the back of the case and scorching the cinder block behind it a little. It apparently never drew sufficient current to trip the 20A breaker. (This was a 240V circuit, but that doesn't really enter into things at all; the potential between either leg and ground is 120V.) Needless to say, I was very, very glad it was mounted on the block wall and not in a wooden framed partition, where it could very easily have started a house fire.
A GFCI would have tripped in this situation. I assume an AFCI also would have tripped, at least if they do indeed work as advertised. Neither were required in this particular application when the house was built, and indeed I suspect that's still the case for a hardwired heating circuit.
As stated and in this particular instance if would have tripped anyway, if it had 3 conductor wire and if portable, a 3 prong plug, which would have included a wire from the case itself. I mean there is a reason why every circuit in a residential home isn't required to have GFI protection. Now I have seen a large CAT dealer's shop that had nothing but GFI protected outlets throughout the place and with also being the only source of portable power available, but then that's a commercial work area.
Also makes it kind of tough for plugging in a coach that won't accept being GFI fed.
If a coach trips GFCI breakers when plugged in, there's usually some fault that's causing that. It is possible for normal acceptable leakage from various devices and their line filters etc. to leak enough to trip a GFCI, but usually that's not the case. Tracking down faults, particularly neutral-ground faults, can be pretty tricky at times.
With my heater, the heater was properly and solidly grounded. Since it was hardwired it didn't have a three prong plug, of course. The short to the case simply had a high enough impedance (probably due to the paint on the case, some surface rust, and the wire brushing it rather than being firmly connected) that it never consumed sufficient current to trip the breaker.
