How often should residential breakers be exercised?

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guyaneesebrotha

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My second floor bathroom fan caught on fire recently.As the fan spun it shot flame on the attic insulation and wood.
These materials smoldered and burned.Eventually the fire burned thru the sprinkler pipe etc!!When the electrical fire met
with water that should have made the breaker trip(it did not).My question is how often should breakers be exercised so
that they disconnect properly?
 

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guyaneesebrotha said:
My second floor bathroom fan caught on fire recently.As the fan spun it shot flame on the attic insulation and wood.
These materials smoldered and burned.Eventually the fire burned thru the sprinkler pipe etc!!When the electrical fire met
with water that should have made the breaker trip(it did not).My question is how often should breakers be exercised so
that they disconnect properly?
Click to expand...

According to the instructions for AFCI & GFCI Breakers monthly.

I don't know about regular breakers though.
 
Mechanically operating the breaker may or may not help it trip under fault conditions. You would have to test the breaker electrically to know if it will trip as specified. I had one old, 40+ years, GE breaker that tripped, but the paddle stayed in the on position.

Either that breaker is defective or, the fault did not cause enough current flow to get the breaker into the trip region.

Since this was in a bathroom can I assume it was a GFI ?
 
Noting that with the amount of dust build up on the motor, it looks like the motor had stopped turning, very common problem with these bath fans, this can cause the windings in them to over heat, but what I find is a problem is there is a thermo-fuse built into windings of every one of those types of motors to prevent just this type of thing from happening.

While I agree that there can be many reasons to why the branch circuit breaker didn't trip, I find more of a problem as to why the thermo-fuse didn't open? looks like a very common Broan/Newtone bath fan I believe a 688?
 
Rick Christopherson said:
Contrary to common misconception, water is not a good conductor of electricity. Contact with water, even when it does lead to ground, does not automatically equate to a tripped breaker.
Click to expand...

True, while enough current may flow to kill a person-40mA?-breakrs will often not trip.

I have seen surge bars, receptacles and light fixtures flooded with the breaker not tripped.
 
guyaneesebrotha said:
My second floor bathroom fan caught on fire recently.As the fan spun it shot flame on the attic insulation and wood. These materials smoldered and burned. Eventually the fire burned thru the sprinkler pipe etc!! When the electrical fire met with water that should have made the breaker trip (it did not). My question is how often should breakers be exercised so that they disconnect properly?
Click to expand...

I pretend to be an electrical engineer, not electrician, and disagree with several "facts" you were given.

I seriously doubt that "it shot flame"; that suggests someone watched it do so; why did they not turn it off.

I do agree that there was smoldering and burning, most likely because the fan was not kept clean and lubricated, stalled, and overheated. How often should the fan be inspected and cleaned? I believe that modern fans have an over-temperature sensor as in hairdryers that interrupted current; if so, why did it not do its job? How often was it inspected? Or is this so old that those switches were not present? Or is it not even equipped with one? If not, why? Was someone too economical to select a unit so equipped?

The electricity meeting water would almost 100% NOT draw enough current to trip even a GFCI ... soapy water in a tub, yes, but clear water from a pipe ... nah. And periodically exercising a GFCI breaker or outlet doesn't help it do its job, just confirms that it is working. I'd go so far as to doubt a line-to-line short occurred, rather that the dirty clogged dry bearing fan overheated. Only the temperature switch had any opportunity, IN MY OPINION, to prevent or minimize damage.

This is just my opinion ...
 
The duty of the breaker is to protect the branch circuit conductors from overheating because of overload or short circuits.

When the fan malfunctioned there was never enough current flowing to endanger the branch circuit conductors.

Supplementary protection of the fan could have prevented this - and is often built into the fan.
 
Rick Christopherson said:
Contrary to common misconception, water is not a good conductor of electricity. Contact with water, even when it does lead to ground, does not automatically equate to a tripped breaker.
Click to expand...

OK..that works for me. I have a brother in law whose basement flooded twice. The panel was completely submerged both times.......lights stayed on sump-pumps kept pumping............


I figured there may have been enough resistance between the busbars and everything through the water as not to blow up????


Would anyone know why this panel could be submerged like that?


Sorry about the fan and fire guyaneesebrotha.
 
don_resqcapt19 said:
Because as Rick said in his post, "Contrary to common misconception, water is not a good conductor of electricity.".
Click to expand...

But it is usually good enough conductor to allow for shock hazards when you combine electricity with water.


Pure water does not conduct very well, dissolved minerals and other impurities increase its conductivity, but it is still not at low resistance like metals.
 
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