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Old 05-16-2010, 12:11 PM   #46
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Testing a breaker


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Originally Posted by Andy-n-ATL View Post
Perhaps it will help if doubters realized that an AFCI breaker is actually two breakers in one. There is a GFCI component, which trips at 30mA (as opposed to 4-6mA Of a regular GFCI) which protects against arcing faults to ground. But what if there is no equipment grounding conductor available? Take a walk around your house and examine all the cords you have plugged in. Virtually all are of the 2-wire variety, which is where the arc fault portion of an AFCI steps in and protects.
With all due respect I will contest you on that. (Statement.) Because the principle of operation of a GFCI (receptacle, breaker or combination breaker.) is that it measures the current flow across 2 wires. Hot and Neutral (Current going in to the appliance and amount of current leaving it.) And if there is a condition of leakage current (meaning part of the return takes a different path.) the device senses it and trips the circuit. To be manually reset after the hazardous condition is corrected. Specifically. There are two coils on both the hot & neutral. When everything is equal they cancel each other out. When there's an imbalance, the circuit trips. !
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Old 05-16-2010, 02:54 PM   #47
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Testing a breaker


Take an exception to what? I am perfectly aware how a GFCI operates. The GFCI portion of an AFCI breaker protects against series arc faults. The AFCI portion of an AFCI breaker protects against parallel arc faults.
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Old 05-16-2010, 02:54 PM   #48
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Testing a breaker


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Specifically. There are two coils on both the hot & neutral. When everything is equal they cancel each other out. When there's an imbalance, the circuit trips. !
See figure 2 in
http://www.national.com/ds/LM/LM1851.pdf
Also note that the GFCI "doesn't know about ground."
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Old 05-16-2010, 02:59 PM   #49
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Testing a breaker


I understand that a GFCI doesnt require a ground...however we are talking about situations here. If a nail is driven btwn the grounded conductor and the equipment grounding conductor and there is a load, then a AFCI breaker, using its crafty GFCI skills will cause the current to be interupted before a fire. A standard OCD will not trip.
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Old 05-16-2010, 06:00 PM   #50
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Testing a breaker


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Originally Posted by Andy-n-ATL View Post
Take an exception to what? I am perfectly aware how a GFCI operates. The GFCI portion of an AFCI breaker protects against series arc faults. The AFCI portion of an AFCI breaker protects against parallel arc faults.
I apologize. But my explanation of the priniciple of operation is no contradiction to your statement in post #45. Where, in the last line you mention that the GFCI part of the (Comb.) AFCI is sensing the difference in current flow bet. Hot & Neutral. no need for!
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Old 05-16-2010, 07:59 PM   #51
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Testing a breaker


As I understand it combo AFCI's are now required
They usually provide GFP

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AFCI breakers do not supply GFCI protection and cannot be used to comply with the necessary GFCI protection requirements of the NEC.
GFCI - Class 'A' trips generally at 5 miliamps
GFP - Class 'B' trips generally at 20-40 miliamps
Cutler hammer does make a GFCI/AFCI combo, possibly other Mfgs do:
Quote:
Cutler Hammer. The 20 amp afci/gfci for a CH panel is CH120AFGF
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Old 05-16-2010, 08:03 PM   #52
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Testing a breaker


10 mA is painful and 18 mA is the let-go threshold. I'm not sure what these class Bs are protecting against.
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Old 05-17-2010, 01:01 AM   #53
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Testing a breaker


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10 mA is painful and 18 mA is the let-go threshold. I'm not sure what these class Bs are protecting against.
The class B RCD { GFCI } will be calberated at 30Ma and they are strictally for equiment protection only but they are avaibale in electrical supply but expect pretty pricey item due not super common item.

The Class A RCD {GFCI } is set for 4-6 Ma depending on manufacter setting.

that part I mention that is used in North Americia side however France we have RCD the normal setting is 30 Ma but we have couple other setting the main breaker RCD will have 100Ma but we do have pool RCD that is much tighter it is at 10Ma.

Merci,Marc
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Old 05-17-2010, 04:33 AM   #54
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Testing a breaker


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10 mA is painful and 18 mA is the let-go threshold. I'm not sure what these class Bs are protecting against.
They are protecting against fire.
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