Quick Electrial Question

[Nova]

Due to the inductance of the windings of larger motors there is a slight delay in the current flow between the hot and neutral leads. This delay can cause a false trip of a GFCI.

[Swingman]

No differences: "Ground Fault Interrupter" vs "Ground Fault Circuit Interrupter".

Otherwise know as an RCD "Residual Current Device", I believe other countries may have other names for them.

Recently there is another device that is now required by code in bedrooms in the many US locales, the AFCI "Arc Fault Circuit Interrupter" ... in the form of an AFCI c'bkr in the service panel. One of the big reasons for this requirement is the recent proliferations of ceiling fans placed in bedroom on lighting circuits, not all properly installed as a retrofit.

[-MIKE-]

Great. Completely out of context, but I agree.

[tiredofspam]

[Swingman]

In the early days of GFCI, even nearby electrical storms were responsible for nuisance GFCI trips.

The advent of "hospital grade" GFCI devices advanced the quality of the devices to where that is no longer the problem it once was, although it still happens and is always something to consider.

[-MIKE-]

I don't know where this is going, but I'm assuming GFCI outlets are rated for different current loads and applications, just like standard outlets.

[tiredofspam]

[Swingman]

Some solutions are considered "perfect enough" ... an oxymoron if ever there was. :)

[tiredofspam]

Around my parts, grounds must be crimped together to join.

[Dave]

Ok, one more question. What if it's just a two pronged plug (no ground plug) as is the case with that fan in the bathroom that I mentioned? Could a two pronged plug produce false GFI trips?

[Stuart]

It's faulty.

We moved into our present house in 1975 and a couple of years later decided to have an electric shower fitted over the bath. The idea filled me with a certain "unease" so we had what, in the UK, was then referred to as an "Earth leakage circuit breaker" (ELCB) fitted by the supply authority. (It sits on the house incomer between their fuse and the consumer unit (Fuse box)). Back then these were very uncommon in fixed domestic installations, though available, but are now mandatory on new installations as they were then on "Mobile homes".

A while later we started getting occasional unexplained trips but as they became more frequent we realised they were being caused by our electric kettle. Clearly the internal insulation was beginning to fail or the seals were failing allowing water to find its way into the wrong place somehow. Once replaced the trips stopped.

I have a 2kW circular saw in the garage, it never causes any problem.

[Dave]

Apologies, should have thought about it a little more before asking. Most device plugs, if not all in bathroom are two pronged and they are what a bathroom GFI would protect against in the case of a water born circuit.

[Dave]

Guess it might be. The fan has been in the bathroom for several years so condensation could well have damaged the fan. I'll toss it just to be safe. Thanks

[Doug Miller]

That doesn't mean you should do them -- or advise others to.

[Doug Miller]

GFCIs are tripped by a current imbalance: if the currrent on the hot and the neutral differ by more than 20mA, it trips.

Inductive loads such as those presented by electric motors put the return current slightly out of phase with the supply current. If the amplitude of the phase difference exceeds 20mA, the GFCI trips.

[Doug Miller]

Same thing exactly: Ground Fault [Circuit] Interrupter.

[Doug Miller]

Absolutely. A GFCI does not need a ground conductor at all in order to trip. They work by sensing *only* an imbalance in the supply and return currents (in the black and white wires, respectively). *Anything* that causes those currents to differ by more than 20mA will trip a GFCI, regardless of the presence or absence of an equipment grounding conductor either in the appliance cord or the premises wiring.

[tiredofspam]

No, the neutral is still the ground.

BTW if you attach a meter to the hot and neutral you'll get voltage. Attach the hot and ground and you'll get voltage.

My house was wired so that neutral and ground are one and the same... My second box was not allowed by code to do that. It had to have neutral and ground seperated... No idea why, but that's code.

[Hoosierpopi]

there were no "romex connectors" going into the junction box, coming out the junction box, or going into the garbage disposal unit. =A0*Scotch tape* was used to cover the sharp edges on the knock-outs on the junction box.... =A0

Redo the electrical and install an outlet for the disposal. Assume the previous "electrician" wired it to a wall switch above the sink - if not, you should do so.

You can, of course, "hard-wire" the disposal to the junction box, but installing a GFCI duplex outlet (or a standard outlet) would be much better from a re-sale perspective. Anything a Home Inspector can readily see should LOOK "right." Anything that doesn't gets flagged and, then, you have to call a licensed electrician to "fix it" prior to closing - no fun and expensive!

[Doug Miller]

Nonsense. Neutral and ground are two different things. A circuit using only two wires has *no* ground.

No, it was not. It was wired without a ground.

For safety.