When replacing an existing outlet with a GFCI the rules are no ground then no ground downstream. when there is a full size ground then connect all grounds. What is the accepted practice when a reduced size 16ga bare ground is connected. Do you open the ground connection, continue the ground downstream; or connect the reduced ground on all devices

I treat it like a full size ground, and attach to all devices.

not sure of the question ? do you mean a/c (bx) cable , what type of boxes ? GEO

LK,

Do you mean the smaller size ground wire that was in the older NM cables?

LK:
In my opinion, a reduced size (wire guage) ground conductor is better than "no ground". The older NM cable had 16 gauge ground, and most of that cable was/is #14, for the hot and neutral conductors, and should be on a 15 amp OCP.

As an AHJ ion NJ, I would accept the undersized ground. For any arguments, I would fall back to "good old common sense", but as there is no NEC article for that, I would use the NJ "Rehab" Code out of the UCC (5:23 et al)

John

I find reduced grounds under cable clamps, twisted under sheet metal screws and pushed through holes in the box. None of these connections are good grounding practices.
When installing a GFCI I find it best to check all down stream ground connections.
It looks like everyone agrees reduced ground better then none at all.
LK

Then of course a reduced ground will show a ground with your average tester, but may increase the resistance enough in the event of a fault to not trip the OCPD. In which case it would be better to mark the GFCI as "no equipment ground" so no one is deceived about the actual grounding ability of the circuit.

Steve:
Good point this is why some type of marking should note the missing link. I have a problem finding a label NO EQUIPMENT GROUND the GFCI Mfg. should put them in the box. They have about 4 info sheets in there now.

LK

LK,

Most GFCI manufacturers now include both labels in the box. (GFCI protected outlet, No equipment ground).

In this situation, why is the existing (reduced) equipment grounding conductor better than none? The whole circuit is protected by a GFCI, which will trip faster than the breaker will, in the event of a ground fault. That is it's function. IMOI, I would think the reduced egc is equal to no egc. Don't use it.

If you are talking about a non-gfci protected circuit, then, yes the reduced egc is preferred to none.
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Rick Miell

In the U.K. our equivalent of NM cable still has the ground wire one size smaller than the other conductors in all but the smallest size.

With no GFI protection, it would be down to whether the loop impedance including the resistance of the reduced ground is low enough to operate the OCPD in a short enough period of time. (That's the criterion used in Britain.)

I don't see a problem with connecting the reduced ground downstream of a GFI on the circuit. The resistance of the EGC is still going to be plenty low enough to trip the GFI on a ground fault.