amps exceding the rating

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i was adding a motion detector to a garage 20i crk its also attached to the ref and kitchen lights,and garagedoor.with draws 6 i..so i turned all the lights on and pluged any appliances that would be on that circuit and went into the panel to check out how many amps its drawing when i had my friend turn on the garagedoor ompener it was drawing 10 amps..then he pluged in a heater that was in the breeze way once he did that the circuit was drwing 22 amps and the breacker never triped its a square d ..is this common ..so ill add the censors but i told him he should have the heater pluged in as least as possible
 

WorkSafe

Senior Member
Location
Moore, OK
How much time did you give the breaker to trip? There are trip curves for breakers that will determine approx. how long until a breaker trips and at what levels.
 
How much time did you give the breaker to trip? There are trip curves for breakers that will determine approx. how long until a breaker trips and at what levels.
about a few min it read 21amps for a min and never triped ...oh ya i have another ? when im adding the censor lights if i want 2 censor lights to go on at the same time i just make a whip for them just like any other light rite.
 

zog

Senior Member
Location
Charlotte, NC
about a few min it read 21amps for a min and never triped ...oh ya i have another ? when im adding the censor lights if i want 2 censor lights to go on at the same time i just make a whip for them just like any other light rite.

Typical trip time for a small MCCB at 110% of rating is 3,000-10,000 seconds.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
It would take awhile to trip as Zog pointed out but the install is already illegal and you are adding to it. :confused: Do it correctly.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
Myth buster #??
In reality, breakers do not operate instantly until many magnitudes (i.e. >500%) of current are flowing.

I would not be surprised that a 20A breaker carrying 22A might never trip.
Breakers are calibrated based on a 40?C (104?F) ambient, cooler temperatures mean longer tripping times.
 

zog

Senior Member
Location
Charlotte, NC
Myth buster #??
In reality, breakers do not operate instantly until many magnitudes (i.e. >500%) of current are flowing.

I would not be surprised that a 20A breaker carrying 22A might never trip.
Breakers are calibrated based on a 40?C (104?F) ambient, cooler temperatures mean longer tripping times.

In a garage, in the summer, 104F is very reasonable. I think my garage was that warm yesterday (86 degrees outside)
 

G._S._Ohm

Senior Member
Location
DC area
Typical trip time for a small MCCB at 110% of rating is 3,000-10,000 seconds.
Is there some elapsed time where a breaker hasn't tripped on a mild overload and you know it's not going to? My new high limit is now 2.8 hours and it can't be much longer than this.
 

zog

Senior Member
Location
Charlotte, NC
Is there some elapsed time where a breaker hasn't tripped on a mild overload and you know it's not going to? My new high limit is now 2.8 hours and it can't be much longer than this.

Assuming you mean MCCB's, you need to reder to the TCC for the acceptable bands, in absence of the TCC's ANSI/NETA MTS and NEMA AB 4 have tables for this, it depends on the breaker voltage and frame size. The maximum allowable trip times are only published for a 300% overload. So when testing the thermal or LT function, which is required to be done at 3xAF, when you reach that time you stop the test and fail the breaker.
 
It would take awhile to trip as Zog pointed out but the install is already illegal and you are adding to it. :confused: Do it correctly.
what was illegal about the the arreginal instal that they have the rif on the same crk as the garage?...the crk is only drawing 9 amps on its own..when the garge door is on
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
what was illegal about the the arreginal instal that they have the rif on the same crk as the garage?...the crk is only drawing 9 amps on its own..when the garge door is on
Az jumner sez; c p ostnmber ate, t hat's wair u wheel fined anser. ;)

Sorry, couldn't help myself. ;)

Roger
 
Az jumner sez; c p ostnmber ate, t hat's wair u wheel fined anser. ;)

Sorry, couldn't help myself. ;)

Roger
roger everyone off my post you always have a wiseazz answer for please do me a favor and dont reply 2 my post you deff think your someone your not....and p.s loose the mustach ...wild earb..heee haaaaa..sorry couldnt help myself..but its true u look silly
 
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S'mise

Senior Member
Location
Michigan
Ok kids, play nice. Got to admit it was a bit funny....and confusing. I was thinking you had a motion detector on the fridge.;)

Aside from circuit arrangement, take a look at the instructions of the frig and the GD opener, they might each need an individual and/or 20a ckt.
 
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