"Nate Nagel" wrote in message
...
Hi all

am looking for a hopefully easy to obtain, not too expensive method of
demonstrating that a receptacle is GFCI protected... long story short. Am
selling house, got offer. Home inspector came through and wrote up two
receptacles as being "ungrounded" despite them actually having the blue
stickers on them that said "GFCI Protected - No Equipment Ground" (duh)
before you ask, it would be fairly difficult to pull grounds to these
boxes, otherwise I'd not be fighting. Also there are a approximately 5 or
6 other receps throughout the house that I haven't grounded yet that are
in a similar situation, and I don't want to open that can of worms whereby
accepting that the lack of a ground at these receps is a fault that needs
to be corrected leads to the request to ground *everything.* (house was
built in 1948, before you ask. I did update a good bit of the wiring
already, just not all of it. Everything is to the best of my knowledge
code compliant at this time, and in fact I got a permit for the rewiring I
did on the 2nd floor a while back.)

SO.

I scanned the page of the NEC (2008 edition, which is what my AHJ is using
these days) addressing the replacement of ungrounded receptacles; called
the head inspector to confirm that there were no local addendums to the
code (he said no) and so I have a case, right? I just need to demonstrate
that the receps are in fact downstream of a GFCI.

Here's where I had a moment of dumbass. I figured I would just stop by
the Local Hardware Sellin' Emporium and get one of those plug in cube
testers - kind of like the one I already have but this time the fancy one
with the little button on the top to test a GFCI. That should do it,
right? Well I get it home (not the house for sale, my current temporary
residence) and plug it in to a kitchen recep, push the button, GFCI pops.
Then I read the instructions - says it may not work on ungrounded receps.
Of course it wouldn't - it probably just has a resistor that the button
inserts between hot and ground so that it allows a current slightly higher
than 5 mA @ 120V. duh!

So the question is - is there a tester available that I could use to
demonstrate the principle to someone who's not really clueful about such
things that the GFCI really works? I could use a test lead to connect the
ground pin to a faucet or something, but I have a feeling that that
wouldn't really help the case that I know what I'm talking about and did a
proper job in front of people who aren't really clueful about electricity
and have never heard of the NEC...

any ideas?


The GFCI works by compairing the current on the hot wire to the neutral
wire. If they are not ballanced, it assumes that current is going to ground
somewhere and opens the circuit.

The only way to test it is to create an unbalanced condition. Many testers
put a resistor from the hot wire to ground. To test the ones without a
ground such as you have, you will need to run a wire from the ground pin of
the socket or tester to a grounded item. Such as to a grounded receptical
or other grounded device.

To demonstrate the recepticals are protected, put a lamp in them and go to
the testor and plug it into the GFCI that protects them. When you trip that
socket, it should cut off the current to the other ones if the GFCI socket
is grounded.