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Circuit Breakers

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Rick

Jan 1, 1970
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I'm building a new house and I've being told by the local electrical
inspector that I need to have an Arc Fault Circuit Breaker for any circuits
in bedrooms. I was wondering what does this type of breaker do I would
think that it's something like the Ground Fault outlets that you see in
Bathrooms or outside
Rick
 
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Louis Bybee

Jan 1, 1970
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It is a specialized breaker that will trip on an overcurrent event, or the
"signature" of an arc fault irrespective of the current level. Such an arc
fault might be a damaged lamp cord, loose connection, defective appliance
that is producing a heat generating arc with current flow that is less than
required to trip the breaker in an overcurrent mode. The idea is to trip the
breaker before the arc can start a fire.

Google "arc fault breaker" for a ton of information on the subject.

Louis--
*********************************************
Remove the two fish in address to respond
 
J

Jamie

Jan 1, 1970
0
hmm, arc fault breaker?
thats a new one on me.
maybe he is talking about a GFI ?
the last GFI i saw has the option to
clamp and open the breaker at the outlet
in the event of lightling hits etc and gounding
problems or miss wired devices.
 
R

Rick

Jan 1, 1970
0
Ok if this type of breaker trips on a short (damaged lamp cord) then what's
the difference between a high resistance short (lamp cord) and say turning
on a light to an ohm meter there both a short of some degree
 
J

Jamie

Jan 1, 1970
0
i just looked and it seems to be a very expensive elaborate breaker.
paying $80.00 on the average for a Square D Home line is not my way
of thinking per breaker.
i just wonder how many fault trips it causes depending on the equipment
connected to it.
i suppose if the electronics is designed to force a trip from a
transient pulse that normally wouldn't trip a thermal breaker would
make some sense.
 
L

Louis Bybee

Jan 1, 1970
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An Arc Fault Breaker will trip on an overcurrent greater than it's rating.
The time to trip is an inverse time curve. The greater the overcurrent the
quicker the trip.

An Arc Fault Breaker also will trip when it detects a "signature" of an arc.
This arc could be line to neutral or ground, with enough resistance limiting
the current below the overcurrent trip rating of the breaker. While the
current seen by the breaker might be below the overcurrent trip rating of
the breaker, thus no trip, it could be significant enough to generate
substantial heat, and a subsequent fire. The arc might also be a series arc
such as a damaged conductor in a cord where the conductor is broken, but not
separated enough to prevent arcing, or other defect (loose connections) in
the current path producing the same type of heat producing arc. An arc
welder is a perfect example of the heat potential that can be developed
without exceeding the breaker trip rating. While the arc welder is a
legitimate use of current, using one on a circuit with arc fault protection
would result in the breaker tripping even though the circuit current rating
wasn't exceeded.

Early implementations of Arc Fault Breakers were plagued by false tripping
from universal motor equipped devices, and other legitimate electrical
consuming devices. Today's Arc Fault Breakers are much improved, but some
normal use electrical devices still give them fits.

They aren't cheap, but in most cases will protect against arc induced fires.

Louis--
*********************************************
Remove the two fish in address to respond
 
R

Rick

Jan 1, 1970
0
Thanks for the explanation, I guess the cost is irrelevant as I will not
pass the final electrical inspection if I don't have one.
Thanks again
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