how to test circuit breaker amps?

Sorry I did not read the question too well did I.

I have my answer. Unless you know what you are doing ttake it to an autoelectrician and ask.

Are you sure its 12V?

Like another poster said use Google with any markings, numbers or info thats on the breaker.

But if it is totally bare toss it out and go and buy the one you want. Beats frying a battery or the wiring.

Phil

Thats why I said to do it ONLY if he knows what he is doing.

And later I said to toss it out and buy a new one.

Phil

Hi Phil
RE:"vk1dx posted:
Thats why I said to do it ONLY if he knows what he is doing"

Even IF he did know what he was doing, how would the time lag factor be taken into account??? using a probe on a heater element???
What watts / voltage heating element?


Sorry but simply not practicable.


Peter

Firstly we are talking about 12V DC.Well being a camping/4WD etc thing that is a reasonable assumption. I did ask but have not had an answer as yet.

I also asked why he would want to. There is obviously more to this question. But I answered it on the assumption that it had to be tested now and that it was 12 volts. If not urgent and at "home", then toss it out and get a new one.

So to answer your question:
Thats how we tested one quite a while ago in the bush. Mind you the fuse that we used in its place was half the current that tripped the breaker. Just in case. I was really talking about bush work. At home. Mits off and get a new one. The same as I tell people when they are at home and obviously are not mechanics and appear to getting in way too far over their head.

As well, I thought it would trigger at a set current. Especially a DC one. The element would be used as a variable resistor. Start at the greatest resistance and slowly work back. Naturally if it got hot then back to square one. Was the time lag to allow for heating? If so then taking it slowly would give a close enough answer to get them going.

Phil

Hi Phil

Ok ,fair enough ,
But If I was in that situation in the bush it would be unlikely that I would have anything like a suitable tappable load.
For a temporary repair I would just use a bit of copper wire for a fuse, wire size required should be easy enough to calculate knowing what load was on the circuit .

ALL thermal circuit brakers have a time lag factor ,its built in by the design, just as wire fuses also have a time lag factor
A typical time lag for a circuit breaker is 2hours @ 25% overload but much depends on the particulat breaker's design.

Peter

I think realistically that I should have asked more questions first! Hey?

Phil

Thanks to both for taking the trouble to reply........I will throw it out................

but the reason for the post was simply because the circuit breaker in question was one I had removed from an old installation on an alarm on the old hilux...........nothing wrong with it but with no markings whatsoever on it...
all I knew was that it was 12V

so in brief nothing wrong with it but I am unable to use it again in any situation without knowing its set point..........if I could test it two things would have resulted..

Most important was that I would have learned something about "how to"

secondly I would have not had to throw out a CB that was still functional..........it was more about the knowledge and less about sounding cheap

Thanks again

Cheers

Hi Bungarra
In that application ,I would expect it would be a low rating.
The smaller the rating the bigger the % error may be .
However IF you do want to play around you would need a few things such as :

A constant voltage source[ battery connected to charger]
As Phil suggested,a tappable load would be excellent.
BUT I cannot t really think of anything, 12v,that you may have suitable.[the old heater or fan resistance speed control is about all I can think of ]

OR a range of loads such as 12v light bulbs up to head lamp size .
An ampmeter up to say 10amps.

You should start with the head lamp & ampmeter connected in series across the battery & leave for several hours or until it trips
If it trips repeat with a slightly smaller wattage load .
If it does not trip repeat with a slightly larger wattage load
You may need to repeat the exercise with various loads until you find a load current that does not just trip after several hrs.
Note: the lamps can be wired in combinations of series or parallel to get various loads

Peter

Thanks again.

understeand the principle of your comments but I will file that away for the future when it becomes necessary to test one one day....or I have absolutely nothing to do to fill in the time..........this one I will bin