GFCI Installation Location

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Old 06-03-20, 04:30 AM
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Cool GFCI Installation Location

I have read the GFCIs must be installed as the first breaker in a circuit in order to protect the entire circuit. Since alternating current by definition alternates, why would it not be effective as the last element in the circuit?
 
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06-03-20, 08:40 AM
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Since alternating current by definition alternates, why would it not be effective as the last element in the circuit?
Think of the GFCI as a switch. If you put it at the end of the circuit How would it be able to turn off the beginning of the circuit.
 
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Old 06-03-20, 07:37 AM
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Hi, the placement of the GFCI device has nothing to do with the alternating of the current,
check this link out it will explain better than I can.
https://science.howstuffworks.com/electricity8.htm
Geo
 
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Old 06-03-20, 08:40 AM
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Since alternating current by definition alternates, why would it not be effective as the last element in the circuit?
Think of the GFCI as a switch. If you put it at the end of the circuit How would it be able to turn off the beginning of the circuit.
 
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Old 06-03-20, 10:11 AM
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When you're doing wiring, knowing that it's AC doesn't really matter. Just consider it similar to DC (+/-), with AC you have hot/neutral. The hot always gets switched (like + gets switched in DC).
Obviously when you get into the theory about how certain things work, there's a lot of difference... but with residential wiring, you don't need to know or care much about those details.

But for a GFI in particular, it's comparing the current in the hot wire to the current in the neutral wire. In normal cases, it should be the same (electricity going 'out' is the same as coming 'back'). If there's a fault to ground, some of that current isn't coming back on the neutral wire (it's going somewhere else to ground). The GFI senses that and trips very quickly.

If the GFI is further down the circuit, it senses current going out and in for its own receptacle, and anything connected to the load terminals. But it's can't 'see' what's happening upstream of it.
 
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