Anyone know the background behind Cecil’s comment in the “Straightdope Classics” article “What does a ground fault interrupter do?”
http://www.straightdope.com/classics/a940812b.html
Cecil wrote:
I’m not aware of frequent malfunctioning of GFIs. I’ve seen an occasional false trip, but I’ve never seen or heard of a failure to trip, which is the point of the test. Just wondering if there’s some GFI coverup / conspiracy lingering that I don’t know about…
Well, I have a personal experience with this. One of those CFCI mothers blew up on me a few months ago.
I bought my house in February of 1999 (built in 1973). It is clear that the house has been remodeled over the years, and certainly many of the electrical outlets have been replaced.
Anyway, the circuit blew for no reason again, as it did often. There wasn’t anything plugged into the outlet and nobody was even in the bathroom. I heard a pop, and then went to investigate. I saw a bit of smoke curl from the outlet, and like an idiot went ahead and pushed the RESET button. At that point there was a small explosion inside the box, like a Black Cat firecracker going off. I thought I was toast, but fortunately no physical harm was done.
I ended up replacing the outlet myself (with another GCFI, but you have to cut ALL power to the house… it’s the BIG SWITCH in your breaker box)!!!
I wonder if I can sue somebody over this… $145 Gigabucks is a lot of money! Class action against GE, anyone?
I went to look at the one in my downstairs bathroom after reading the article, and there is a sticker that says “Please test by pressing the yellow button once a month. You should then see the white line on the red button. Push the red button to reset.”
Had you been regularly testing yours once a month? 
Arnold, I think the key in this instance is that he saw smoke from the tripped outlet, and still tried to reset it.
If you see smoke from an electrical circuit, that’s a good sign that something is wrong and needs to be replaced, preferably by a qualified electrician, before you try to reapply the power.
Irishman
Depends on what you mean by key. It’s entirely possible for there to be an electrical short between the two hot wires and not trip the GFI. In fact, this is likely. The real key is that we don’t typically want any new paths to ground. The test button on your GFI outlet creates a short to ground. If the GFI trips then the socket is disabled. The kind of GFI malfunction that Cecil was referring to (the only one relevant to testing the GFI) would be a situation where either you press the test button and the GFI fails to trip or (God forbid) you drop your hair dryer into the bathtub while you’re standing in a foot of water and your GFI failed to trip. I’m sure GFI malfunctions of this nature exist, but I would think they are fairly rare… except that Cecil claimed they were “often”.
I have personally experienced the second case, although at a sufficiently low current level that it might not have triggered. The electric path was from the toaster (a piece of unidentifyable foodstuff had fallen so as to touch both the heating element and the case, and apparently it was badly designed, the element was hot when turned off--that's what polarized plugs are supposed to prevent!) through me and to the sink (the metal frame around it's edge). The contact with the toaster was damp (I was wiping it off), the sink was dry. I could feel the current but it wasn't to the level of hurting or anything. The outlet was GFI, it didn't trip (but would trip if you hit it's test button.)It’s possible to feel a tingle and not be within the GFIs trip current range. Most GFIs trip at around 5mA, but the human body can detect (via tingling) as little as 1mA, under the right conditions. Nevertheless, I’d get that socket checked out, just in case.
And replace the toaster.
Were you installing a GFI outlet or a GFI breaker? If just an outlet, why did you need to turn off all of the power to the house?
When I was learning how to do minor electrical repairs, my brother made me replace switches and outlets with the power on. In his opinion, at some point in your life you’ll turn the wrong breaker off and your test light won’t work (or you’ll be too lazy to use it correctly - who really tests the light, then the circuit, then the light again?) If you get used to working with live power, you learn to do it safely. Once you ingrain the safe habits, you’re much less likely to get blowed up when you’re working on more hazardous wiring jobs. (I think it’s next to impossible to get badly hurt on 110V 15-20A circuits, but on 220V or stuff coming from the meter it’s a different story…)
I’ve been hit with 110V a bunch of times and I’m still walking around… usually it just ‘feels good’. I was hit with 220V once and it knocked me unconscious for about 5 minutes.
Once I was shocked by an arc welder. Supposedly it was about 400V and 300A. It gave me quite a jolt, but didn’t knock me down like the 220V/20A shock did. All of the juice was going through me… I know this because as soon as I felt the shock I stepped off of the metal pipe that I was standing on and onto an insulated pipe. At that instant the circuit was broken and the arc died. I’m not sure why the 220V/20A seemed to cause more damage…