AFCI and GFCI


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Old 09-14-12, 06:10 PM
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AFCI and GFCI

I understand the technical difference between the two (well "understand" might be a little strong...)

But here is my question. Are ALL breakers in new construction now required to be AFCI? Or are kitchen, bath, laundry rooms, etc still supposed to be GFCI breakers?

Because it seems to me the safest thing for, say, a kitchen would be GFCI receptacles (to protect the kid who drops the panini press in a sink full of water) on AFCI breakers for arc fire prevention. Does this make sense?

I would like to start replacing my breakers as I can afford to and want to make sure I make the correct/smart investment.
 
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Old 09-14-12, 06:25 PM
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Kitchens and bath do need protection as do garages and laundries but they do not necessarily have to be on GFCI breakers. Depending on your panel it may be cheaper to make the first receptacle on the circuit GFCI.
 
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Old 09-14-12, 06:29 PM
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Depending on your panel it may be cheaper to make the first receptacle on the circuit GFCI.
That is typically what I do for GFCI protection....my question is should I then install AFCI breakers for those GFCI-protected circuits? Is that sensible/possible?
 
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Old 09-14-12, 07:30 PM
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my question is should I then install AFCI breakers for those GFCI-protected circuits? Is that sensible/possible?
Basically, no. The trick is remembering which loads in which spaces reqiire which protection. If any.

For example, a refrigerator doesn't need either. Some of us hit that first thing out of the panel on the way to the countertop. Same for the 120V controls on a gas cookstove.

The two 20A small-appliance circuits for the countertop receptacles in the kitchen need GFCI protection. The two 20A small-appliance circuits in the dining room do not - but they do need AFCI protection.

This is the best guide I have found to this: Mike Holt’s Illustrated Guide to Understanding the NEC Requirements for GFCI and AFCI Protection. It's based on the 2008 NEC, when the big changes happened. The 2011 cycle made some minor changes, but you should be safe following this.
 
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Old 09-15-12, 07:41 AM
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How they work:

GFCI measures the imbalance between the two wires of the circuit. If it is greater then 4-6 mA, it will trip. Imbalance indicates voltage is leaking to ground.

AFCI "watches" the sine wave of electricity. If it "sees" an arc pattern it will trip.

As you can see they do very different things.

Nash pretty much covered the other stuff.
 
 

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