Do you test your breakers?

[MillWeld]

Not about tractors but definitely about safety unless your tractor is in a barn where you have the problem I had.

I had a roof vent fan quit operating. I removed it, found a nearly frozen bearing AND a short between ground and hot - just a few ohms. Why didn't the 15 amp breaker trip, I asked? To test it I plugged in heaters into a receptacle on the same circuit as the fan and measured the amps as I added more. I got to 23 amps without the breaker tripping and decided I had better stop! It is a Square D space saver tamdem breaker. Who checks their breakers to see if thay are in specs?

 

[Treemonkey1000]

Good point. Was that a 23 amp surge or constant running? They will handle a higher surge for a short time. Is that breaker out where there is a lot of moisture possibly causing corrosion on the trip mechanism? Good thing you caught it before the wiring melted or fan caught fire. Maybe go through and cycle the rest of the breakers several times to loosen them up. Other than the hassle of what's connected to them.

 

[jagyzf]

Depends on how long you had the 23 amp load and the type of breaker. Some breakers trip due to an instant huge load, or a small overload over time, others trip as soon as you go over the 15 amps.

Not to say it can't happen, but I have never seen a breaker fail and able to pass power. They have always failed not being able to pass power.

 

[Qapla]

Since breakers trip from heat, it could be that you did not give the breaker long enough to properly heat up and trip.

When there is a "dead short" a breaker will usually trip fast since it heats up rather quickly. When you just have a power overload by "over-amping" the load without a short, the breaker heats up much slower.

When you were doing your test did you just add the amps that the heaters are supposed to use or did you actually measure the amps with a meter? How long did you let them run with the 23 amp load?

If you think you have a real problems/concerns about slow tripping breaker, perhaps you should try GFCI breakers and see if they trip at the speed you are looking for.

 

[JB4310]

Yeah I think it didn't have enough time to trip with the heater load anyway.

As a contractor I sometimes trip customers breakers, but they never trip right away either, it's always after running the power tools for awhile.

Actually doesn't happen as much as you would think, so there has to be a delay, not just sensing amp draw. otherwise we'd be tripping alot more.

JB

 

[Bird]

I was wondering about the "roof vent fan". I don't know how many people still use powered roof vents. When I bought a new house in 1977, I talked to a fire department captain Dallas about roof vents and he said he had no proof, but that they suspected a lot of first started in attics as a result of those roof vent fans shorting and the homeowner would never notice the fan wasn't working. So I had wind turbines installed instead.

But to answer the question, nope, I never "test" my breakers. I have on rare occasions overloaded something and caused a breaker to kick off. The only breakers that have ever kicked off in this house are the GFI breakers in the garage.

 

[slowzuki]

Breakers are like time delay fuses, slow blow. You'll see many motor starting requirements list breakers or time delay fuses as a requirement to prevent nuisance trips.

 

[MillWeld]

I actually measured the amps with a clamp-around meter. The first heater brought the amps near to 15 so I added a 2nd one which brought it to 23. The total time at 23 was probably less than a minute - didn't really time it. I didn't know the trip mechanisn was heat related; I expected a near immediate trip. I didn't want to wait and wait for 23 amps to trip it so I removed the heaters. Maybe it was premature but I replaced the breaker today.

The fan IS actually on a GFI circuit and that is what alerted me to the problem in the first place; it shut down several receptacles and overhead lights. Finally traced it to the bad fan which had TWO problems - bearing and short. I'm glad it is on a GFI given Bird's warning.

Actually, in retrospect, we have had intermittant problems with that circuit which would, apparantly at random (we thought), trip the breaker. I suppose a winding was degrading and occasionally contact the frame causing a ground fault and finally got bad enough to be permanent. I'm looking for a replacement motor.
Bob

 

[MoKelly]

It is a good idea but I have zero knowledge or ability to test a breaker. I would have to have an electrician perform the work. Would it be worth the cost? Perhaps have it done when the electrician is over doing some other work?

MoKelly

 

[JRobyn]

Square D markets at least two different classes of breaker - one of which is "QO" or Quick Open. I assume that the QO breakers are faster-acting than their others. They publish time/current trip profiles for all of them somewhere deep in the recesses of their website. I have seen them, but I don't recall what the "delay" looks like. I would hope that the maximum amount of time that the breaker would remain un-tripped once it reaches the rated load is within a few seconds!

- Jay