Pro-melt furnace tripping GFI plug

[D.Mack]

Yes grounging problems can be fun. Last year my neighbor had a cable install update. AS we watched the installer explained he had to ground to the metal valve on the cold water pipe, he insisted it was necessary, and required by code. The only problem was the metal fixture, was attached to pvc pipe where it went into the ground. We waited till he left then ran 5 feet of wire to the houses grounding rod. DM

[D.Mack]

HPDRIFTER, or CRAZY MARK, (or any one else who knows more about electricity than me). What would be the results in this case if the polarity of the wires were crossed on the GFI? I know this would be a potentialy hazardous situation, but may not be apparent at first. DM

[crazy mark]

The GFIC shouldn't work. In other words you couldn't hit the reset button and get it to stay on. I recently had that problem on an older house. the hot and neutral had been reversed in the outlet in the front room that fed the GFIC outlet on the front porch. Once I straightened that out all was fine. All outlets are color coded. Brass color terminal is the hot or ungrounded wire, silver is the white or grounded wire and green is the grounding wire. Back at your panel box the white and ground wires are actually connected by being bonded to the electrical box. They do serve different purposes however. The neutral carries the unbalanced load and the ground provides a path for a short to ground so you don't get shocked when you touch something metal that has a "hot" case. Mark Oregon licensed LME and LEA electrician.

[versifier]

Yes grounging problems can be fun. Last year my neighbor had a cable install update. AS we watched the installer explained he had to ground to the metal valve on the cold water pipe, he insisted it was necessary, and required by code. The only problem was the metal fixture, was attached to pvc pipe where it went into the ground. We waited till he left then ran 5 feet of wire to the houses grounding rod. DM

Depending on the pH of the water and what happens to be dissolved in it, grounding to the water line can cause the electrolytic deposit of minerals on the inside of the copper pipe, sometines very quickly. I have seen similar grounding efforts by the telephone company clog up a 1/2" pipe in a month's time. The ground is required by code, not the hooking up of the ground wire to the water pipe - that's just laziness in my opinion. Btw, just the water in the line was enough to properly ground a low voltage setup like the cable line even if it ran in pvc for a stretch (most older municipal lines are cast iron), but that doesn't mean it wasn't a smart idea to hook it up to a real ground instead, it was.

[Dale53]

Versifier,
You are certainly correct on the telephone line ground connected to a water pipe causing electrolysis on copper pipe. I had pipe start to leak. When I took the bad section out, I examined it closely and could readily see the electrolysis damage. I called the pnone company, they tried to give me a "ration of s**t". I calmly explained the problem in terms they could understand. They installed a proper ground rod that day!! That has been nearly twenty years ago and I have had NO problems since.

Dissimilar metals will cause the same problem (galvanized tees with copper pipe, for example).

Dale53

[mazo kid]

A couple of years ago, I purchased a used ProMelt pot off ebay. I didn't use it for a few weeks, but when I plugged it in and warmed it up, it tripped the GFCI. Moved it to another circuit and same thing. Long story short, when it returned from RCBS rebuild, it was still doing the same thing. Moved it to a regular outlet and it works fine; put my meter on the metal housing and ground and no leakage there.I am a retired electrician and I agree with someone earlier that said tools and GFCIs sometimes don't get along, depending on type of tool. We used to have a lot of "nuisance tripping" when GFCIs were used in garages with electric openers. Emery

[454PB]

While I was still working, we had to test all our power tools and extension cords yearly. The tester was basically a very sensitive GFCI. We had probably 200 items to test each round, and there was always several that failed the test. If it was an extension cord or drop light, it was more cost effective to replace it, but the more costly tools sometimes took many hours to track down the trouble and repair it. Sometimes it was a simple as using compressed air to blow carbon dust out of the armature. We had a very old but well made and expensive to replace bench grinder that took me several days to fix. Bull headed I guess, but I finally got it to pass by insulating every single bolt hole where the grinder was secured to the stand. This repair was really a bandaid, but hey, it passed the test!

I'm convinced that other than a faulty GFCI (which is fairly common), given enough time and effort, hot to ground leakage can be found and remedied.

[grumpy one]

I'm convinced that other than a faulty GFCI (which is fairly common), given enough time and effort, hot to ground leakage can be found and remedied.

It may not be worth doing though. I had a three-phase motor get immersed in water a year or so back, and it developed earth leakage through the windings after drying out. Maybe if I'd flushed it with clean water enough times it might have cleared up, but it was an old open-frame motor that wasn't exactly state of the art, and I'd never have trusted it again. I tossed the motor, and went to quite a bit of trouble to fit a modern one to the big pedestal grinder it was driving. (It happened that the cheapest nice aluminium-cased sealed motor I found was for an odd speed, so there was pulley work involved as well as motor mounting.) Now that it's done, I'm happy with my choice.