This is for an aquarium in a house built in the 1950s with hot and neutral, no ground. I can’t get to the wall box, there is a 100 gallon aquarium in the way.
It is fed by an extension cord and mounted in a box attached to the aquarium stand.
I can’t get it to reset. There is 120v at the hot and neutral screws.
What am I doing wrong?
If you can’t get it to reset, then the most likely explanation is that whatever caused it to trip in the first place is still there. Find that, and fix it.
It is brand new out of the box.
Then what I said is doubly true. I would expect a brand-new GFCI to be working properly, and what I described is the GFCI working properly.
Sounds Like you did the wiring?
There are extension cords with GFCI’s built in.
There is no demand for a ground connection.
The GFCI will trip from an imbalance between the primary and the neutral and if there is an imbalance it will assume that is caused by current going to ground and the chance of that path including you or a loved one is the reason behind the GFCI.
Get the corded GFCI
or here,
Thanks, Gbro.
I don’t see what could trip it. There are no circuits on the load side, and I tested it with a lamp plugged in.
OK, fact established and suggestion made and seconded.
Thank you Gbro for the ‘how’ of the GFI/GFCI’.
Now my Q/observation:
Are there a significant number of residences (SFD or Multi) in the US with real grounds - as in 30’ copper rod driven into real soil, not sand, (or other, equivalent, technologies)?
Every house I’ve seen uses ‘ground-to-neutral’ and I have yet to see a service box with a factory-installed ground buss.
I bought a copy of the little red Residential Building Code book when I started moving walls and adding bathrooms (yes, the tub IS over a load-bearing wall, thank you) and saw no requirement for an electrical ground.
So the GFCI is simply looking for a neutral shorting to a water pipe or something? I assume it would also trip if hot shorted to neutral, but wouldn’t any CB do that?
I did find a light (knob and tube) circuit with the switch on the neutral, It was an exterior light and would always glow a little, even when off. I finally traced it to a short in the fixture, and worked backwards to find the misplaced switch. Would a GFCI have tripped if connected to the wiring in the fixture? I wanted to test it, but forgot.
The grounding system for your house is bonded to the neutral wire from the power company at exactly one place - inside the main panel. So there is no need for a separate grounding bus inside the main panel, but any subpanels must have isolated neutral and grounding busses (with the grounding buss bonded to the metal panel.) With the exception of the main panel, every single location in your house must keep ground and neutral separated. The reason is because they are for separate purposes; the neutral is for return current, the ground is a safety feature. Once you get outside your house, there is no separate grounding conductor, the neutral is grounded at the transformer, and your main panel should also have (at the least) a connection to a copper water pipe or (preferably) a connection to a real grounding rod driven into the soil, or both.
The GFCI is looking for any difference in the amount of current drawn from the hot wire and returned via the neutral wire. If there is a difference, the GFCI assumes that some of that current must be being diverted elsewhere (possibly via a human) and shuts off. A dead short will trip a traditional CB, but it’s possible to have a ground fault (e.g. electrocuting yourself in the tub) without tripping the CB because your body has quite a lot of resistance, and thus it won’t necessarily overload the circuit. That’s why GFCIs are required in wet places.
Probably not, because there would not be a ground fault normally. But switched neutrals are unsafe for other reasons, mainly because the light box can be hot even though the switch is turned off.
Thanks!
The 1984 cook top came with the green wire bonded to neutral, but did note that it Might not be allowed by local code.
[QUOTE=usedtobe]
The 1984 cook top came with the green wire bonded to neutral, but did note that it Might not be allowed by local code.
[/QUOTE]
That used to be standard practice, but now, in new construction, ranges and clothes dryers need to have 4-prong plugs with separate neutral and ground.
There are more old homes with three-prong plugs than new homes with 4-prong plugs, so the appliance makers ship ranges and dryers with the connection bonded. Not to mention, that if they shipped unbonded, and the installer (usually a homeowner, rather than an electrician) isn’t paying attention, the frame/case could be left ungrounded and potentially deadly.
Forgot to mention for the OP, it’s not impossible that the new GFCI is defective. Something to try first is to wire it to the extension cord but not screwed to or even touching the box or aquarium frame, in case there’s some weird sneak path or leakage going on.
In Olden Tymes, this was a common practice, because with a 240v circuit, the neutral wire carries almost no current (the two hot phases cancel each other out.) Thus, it was deemed acceptable to use the neutral as a ground. This is no longer allowed for new construction - 240v appliances must have four-prong plugs with a separate neutral and ground. But many come with a way to configure it for a three-prong plug if it is being installed in an older house.
I tried that already. I meant to bring it to work and test it, but it’s Monday. 
I bought a different brand, and it works.
Now I have to find a homeless person and pay him $20 to pour a bucket of salt water over one of the power strips.
