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Jajal
 
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Default 15A Circuit Breaker on a Power Tap

Hi Everyone,

I dont know if my experiment is proper way to test circuit breaker, I
appreciate your suggestions and/or comments.

I have a Relocatable Power Tap that only has power on/off switch with
built-in 125VAC 15Amp circuit breaker. Since the circuit breaker is rated
for 15 amp, I connected two heatgun with total ampere rating of 20 amp and
turned the heat gun on to heat to draw maximum current. The circuit breaker
did not tripped even though the draw current was more than 15 amp. Why?

Then I added a third heat gun rated at 12 amp. Now I have total of 32 amps
of current draw, the circuit breaker finally tripped after few minutes. One
interesting thing I learned was the amount of time circuit breaker triped
vary among different power tap or surge protector. Some has quick respond
and some are little slow to overload current.

Is there a proper way to test circuit breaker?

Please advise.

Thanks,
San


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scada
 
Posts: n/a
Default 15A Circuit Breaker on a Power Tap


"Jajal" wrote in message
. ..
Hi Everyone,

I dont know if my experiment is proper way to test circuit breaker, I
appreciate your suggestions and/or comments.

I have a Relocatable Power Tap that only has power on/off switch with
built-in 125VAC 15Amp circuit breaker. Since the circuit breaker is rated
for 15 amp, I connected two heatgun with total ampere rating of 20 amp and
turned the heat gun on to heat to draw maximum current. The circuit

breaker
did not tripped even though the draw current was more than 15 amp. Why?

Then I added a third heat gun rated at 12 amp. Now I have total of 32 amps
of current draw, the circuit breaker finally tripped after few minutes.

One
interesting thing I learned was the amount of time circuit breaker triped
vary among different power tap or surge protector. Some has quick respond
and some are little slow to overload current.

Is there a proper way to test circuit breaker?

Please advise.

Thanks,
San



The circuit breaker is designed to trip under a fault condition at 15Amps.
That type of trip is an instantaneous rise in current. An overload (such as
you created) will maintain that current for a pre determined time, depending
upon the design of the breaker may be minutes! The fact that the breaker did
trip shows that it is working. You are doing a dangerous experiment here!
You put a 32 amp load into the strip, but what was the house breaker rated
at? You are overloading your house wiring, possibly causing problems to it!
Not to mention the current stress put on the power strips wiring! That
current is dissipated in the form of heat, putting undue strain on the
wiring, receptacles, breaker, etc... Generally speaking, if the breaker
holds in the closed position, it will most likely trip when needed. You
don't have the equipment to test it as it should be tested.


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Jajal
 
Posts: n/a
Default 15A Circuit Breaker on a Power Tap

Thanks, What test equipment do you recommend for testing circuit breaker? -
San


"scada" wrote in message
et...

"Jajal" wrote in message
. ..
Hi Everyone,

I dont know if my experiment is proper way to test circuit breaker, I
appreciate your suggestions and/or comments.

I have a Relocatable Power Tap that only has power on/off switch with
built-in 125VAC 15Amp circuit breaker. Since the circuit breaker is

rated
for 15 amp, I connected two heatgun with total ampere rating of 20 amp

and
turned the heat gun on to heat to draw maximum current. The circuit

breaker
did not tripped even though the draw current was more than 15 amp. Why?

Then I added a third heat gun rated at 12 amp. Now I have total of 32

amps
of current draw, the circuit breaker finally tripped after few minutes.

One
interesting thing I learned was the amount of time circuit breaker

triped
vary among different power tap or surge protector. Some has quick

respond
and some are little slow to overload current.

Is there a proper way to test circuit breaker?

Please advise.

Thanks,
San



The circuit breaker is designed to trip under a fault condition at 15Amps.
That type of trip is an instantaneous rise in current. An overload (such

as
you created) will maintain that current for a pre determined time,

depending
upon the design of the breaker may be minutes! The fact that the breaker

did
trip shows that it is working. You are doing a dangerous experiment here!
You put a 32 amp load into the strip, but what was the house breaker rated
at? You are overloading your house wiring, possibly causing problems to

it!
Not to mention the current stress put on the power strips wiring! That
current is dissipated in the form of heat, putting undue strain on the
wiring, receptacles, breaker, etc... Generally speaking, if the breaker
holds in the closed position, it will most likely trip when needed. You
don't have the equipment to test it as it should be tested.




  #4   Report Post  
scada
 
Posts: n/a
Default 15A Circuit Breaker on a Power Tap


"Jajal" wrote in message
et...
Thanks, What test equipment do you recommend for testing circuit

breaker? -
San


"scada" wrote in message
et...

"Jajal" wrote in message
. ..
Hi Everyone,

I dont know if my experiment is proper way to test circuit breaker, I
appreciate your suggestions and/or comments.

I have a Relocatable Power Tap that only has power on/off switch with
built-in 125VAC 15Amp circuit breaker. Since the circuit breaker is

rated
for 15 amp, I connected two heatgun with total ampere rating of 20 amp

and
turned the heat gun on to heat to draw maximum current. The circuit

breaker
did not tripped even though the draw current was more than 15 amp.

Why?

Then I added a third heat gun rated at 12 amp. Now I have total of 32

amps
of current draw, the circuit breaker finally tripped after few

minutes.
One
interesting thing I learned was the amount of time circuit breaker

triped
vary among different power tap or surge protector. Some has quick

respond
and some are little slow to overload current.

Is there a proper way to test circuit breaker?

Please advise.

Thanks,
San



The circuit breaker is designed to trip under a fault condition at

15Amps.
That type of trip is an instantaneous rise in current. An overload (such

as
you created) will maintain that current for a pre determined time,

depending
upon the design of the breaker may be minutes! The fact that the breaker

did
trip shows that it is working. You are doing a dangerous experiment

here!
You put a 32 amp load into the strip, but what was the house breaker

rated
at? You are overloading your house wiring, possibly causing problems to

it!
Not to mention the current stress put on the power strips wiring! That
current is dissipated in the form of heat, putting undue strain on the
wiring, receptacles, breaker, etc... Generally speaking, if the breaker
holds in the closed position, it will most likely trip when needed. You
don't have the equipment to test it as it should be tested.




Looking back on my original email, I realize I should of detailed my
explanation better. Let me begin by clarifying that the higher the magnitude
of the fault current (above the rated trip value) the faster the breaker
will trip! The actual overload trip current should be the trip rating plus
any tolerance. With that said, I will continue to say....

Although your calculations added to be a total of 32 Amps, in reality it
would be a lower current. A heat gun is a resistive load, the nameplate
rating of say 12 A would be at initial turn on when the element is cold. As
the element heats up, the resistance increases therefore lowering the
current. The only accurate way to measure the load current would be to use a
current meter. The current meter is put ***IN SERIES with the load being
measured. An easier and safer way would be to use a "Clamp on" ammeter. This
meter actually clamps around ONE of the two load conductors, that way the
circuit does not need to be disconnected. The type of breaker you are trying
to measure is a "Thermal type". It has two bi-metallic metals inside which
heat up (proportional to the current) and at some point it will expand
enough to open the electrical contact. These work fine, although don't
expect good accuracy. Because they are mass produced and cheap, the
acceptable tolerances are typically wide. A typical breaker may be rated for
say 20% giving an upper tolerance of 24A for a 20 A breaker. You would have
to contact the manufacture for the actual tolerance. Because the heat is
somewhat a function of current and time, under an actual fault the breaker
may take seconds to open, depending upon the magnitude of the overload. I
suppose if you were really determined to find the trip current, you could
devise a suitable load while monitoring the load current with one of the two
meters I mentioned. I would assume the breaker should trip within 20% of its
rating, within a reasonable time. Keep in mind that the breaker is largely a
mechanical device, and extensive testing may cause it to fail when you
really need it! Such tests are usually done on a like unit that will be
sacrificed.

***A current meter is always put in series with the circuit NEVER in
parallel, such as with a voltmeter! This can be dangerous if not done
correctly as the meter could explode!


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