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I found a couple of related questions about one GFCI for several outlets

But I am not finding anything about how many outlets I can have on the load side of the GFCI.

What is the max number of outlets on a GFCI circuit?

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There are no limits on the number of receptacles per 15A or 20A circuit in general, though there may be in some jurisdictions. See, for example Is there an average number of outlets that are wired off of one circuit breaker?

A GFCI, whether as part of a breaker or combined with a pair of receptacles, is only monitoring for a difference between hot & neutral - i.e., watching for some current to go missing. As long as the total is less than the capacity of the GFCI device, which itself should be matched to the capacity of the overcurrent protective device (fuse or circuit breaker), it really doesn't matter how many receptacles or devices are connected.

There is a theoretical issue as follows:

A typical GFCI trips in the range of 4-6ma. You could have a bunch of devices that each leak 1-2 ma, which is generally safe. The cumulative effect of these devices on one circuit (which could easily be with as few as 4 receptacles, so you don't need "lots of receptacles" for this to happen, but the more you have, the more likely it will happen) would be enough to trip the GFCI. Yet when you go back to the "unplug everything and plug in one at a time to see where the problem is", the problem device might never be identified - and yet the tripping would continue.

However, I suspect that only a very small percentage of devices would ever have this low level of current leakage without gradually progressing enough to be a problem. Plus this could happen even with just a few receptacles.

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    Actually, your last paragraph isn't quite right -- Y capacitor leakage (which is generally rather constant, as it's basically a factory-designed-in leakage current source!) on non-hand-held Class I (earthed metal chassis) devices can be fairly high, up to 3.5mA as per IEC/UL 60950-1 and related standards; this means that a mere two devices can trip a UL 943 Class A GFCI under worst-case conditions. – ThreePhaseEel Jul 27 at 4:52
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There's no limit. A standard GFCI will protect up to 20 amps, drawn from any combination of receptacles, either the built-in one or any number of additional ones connected to its load terminals. If you're trying to add GFCI protection to an existing circuit, you needn't worry about how many outlets are downstream on the 'load' side, assuming things are correctly wired presently.

Now, if you're installing new circuits, from a practical standpoint, you might want to keep the number of outlets per circuit reasonably low, and instead run separate circuits (with their own GFCIs) for additional outlets, not because the GFCI couldn't handle more, but because you might want to use more than 15-20A at a time in a given location.

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