Max distance from GFCI load side receptacle

No limit in a residential setting.

What is the recommended max distance?

Using a single GFCI receptacle and connecting to it 4 regular receptacles downstream where the last one will be about 100' away, seems too good to be true. I thought the greater the distance from the GFCI receptacle, the longer the shock will be before GFCI cuts the current.

I have seen numbers from 250 to 1000 feet. There is no hard limit. 100 feet is not a problem.

AidaCarrell said:

What is the recommended max distance?

Using a single GFCI receptacle and connecting to it 4 regular receptacles downstream where the last one will be about 100' away, seems too good to be true. I thought the greater the distance from the GFCI receptacle, the longer the shock will be before GFCI cuts the current.

Click to expand...

Electricity in wires travels at (almost) the speed of light (i.e. 300,000 km/s)

Hence, the time "delay" over 100 Feet (30 m) would be 0.1 micro-seconds.

The response time of these domestic devices is likely to be 30 milli-seconds, or greater.

For comparison, one half-cycle at 60 Hz is 8.33 milli-seconds (8333 micro-seconds) so it takes 4.17 milli-seconds (4170 micro-seconds) to reach peak voltage.

So, even with a GFCI it is likely that it may take two full cycles before the circuit is actually "interrupted" and, hence, the "extra" 0.1 micro-second is insignificant.

If you are really worried about it, put a gfci at every location.
That way, if you trip one for whatever reason, you don't have to make a 200' round trip!

jbfan said:

If you are really worried about it, put a gfci at every location.
That way, if you trip one for whatever reason, you don't have to make a 200' round trip!

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If YOU trip one you really should worry more about that than a 200 feet round trip.

Personally, I use a GFCI receptacle on every outdoor receptacle. When you discover the trip, you know where the problem is. With a daisy chain, your problem can be at any of the 5 locations.

It can also save you a rushed trip to the store to buy that GFCI. In the daisy chain they are all dead until the GFCI is replaced, or the problem is fixed, With the individual GFCIs, you have 4 others to choose from. One of them is probably close enough that it can most likely be reached with an extension cord.

You can usually complete whatever it was you were doing and then repair the problem another day.

I do not know if there is a NEMA Standard or recommendation for maximum length


But there is a maximum distance but it is going to vary depending on the leakage current of the insulation for the conductors you are using, the moisture they are exposed to, the conditions inside the boxes, the equipment you are using ( the leakage current of the conductors combined with the leakage current of the equipment you are using) and of course the distance from the GFCI breaker or receptacle.

And of course over time the insulation will deteriorate adding to the leakage current.

The last I knew, square d clearly stated that the circuit length on their QO gfi breakers is limited to 250 ft. I would be hesitant to use any GFCI device for protection beyond that length without getting a statement from the mfg that theirs is good to xxx ft.

I am not sure whether the length limit has to do with the protection or trying to reduce/eliminate false trips.