I have a wall outlet controlled by a switch on the wall. Today I noticed that when the switch is on, the outlet reads 122VAC. When the switch is off, it reads 40-42VAC. Um…keeping in mind I’m going to call an electrician about it, is there a common problem that would cause about 1/3 voltage to appear at a wall outlet?
As a follow-up question - I’ve just got the 2008 NEC book, all 1400 pages of it. I can’t find in there where it says that new wall outlets must be installed ground conductor-side up, even though I’ve had not one but two actual electricians gruffly tell me that “the electrical code requires it”. Can anyone point me to the chapter and verse?
I actualy had this one - it was a case of the switch installed on the neutral, and the fixture (exterior light) had shorted to ground - the hot line was connected reqardless or switch position, but when it was “on”, the return had a nice, spiffy route, when “off”, it had to rough it over the ground. Is there a ground either in the switch box, or is the outlet grounding in some creative manner?
Hm…as far as I can tell, there is no ground at either the switch or the outlet (it’s an old house, the circuits aren’t grounded except for a couple which have long, circuitous lines running to the plumbing). I’ll see if I can take a look when I get back home.
Is it by chance an illuminated switch or socket and somehow you are reading the voltage drop across the little tiny neon bulb?
Other than that the only two things I can think of are a defective breaker, or (and this one is a doozy) you have:
[li]You have a shared neutral[/li][li]another consumer upstream from the socket turned on (electrically further away from the panel)[/li][li]High resistance in the neutral leg between your socket and the electrical panel[/li][li]You were measuring between the neutral and ground[/li][/ul]
Then I could understand 42V on the neutral leg.
Other than that, I got nothin. We need Danceswithcats he is our resident electrician IIRC
I’d like to see that, too. (You are referring to the ground conductor pin on a 3-prong socket, aren’t you?) I always thought the 3rd pin should be DOWN, as that’s the way I see it most of the time. Is the new style UP, and if so, why?
From what I can tell, the “it’s in the code” I was told was really the electrician saying “I just want to do it this way”, thinking Ms. Dumb Homeowner wouldn’t know nothin’ about no code. I also called my city and county and discovered there was nothing in the building codes either.
The number of times I’ve had someone say “it’s in the code” and it be wrong is astonishing.
Hmm…just noticed, we can’t edit our posts…anyhow, the ground-pin-up I’ve heard called the “Catholic safe” configuration. Because the urban legend goes that Catholics, leaning over to plug/unplug a socket, would somehow, against all logic, frequently get their rosary tangled up in it and electrocuted. And yet, I’ve had “master electricians” tell me this swearing they’ve “heard it happen so many times”. :rolleyes:
What sort of meter are you using? A DVM will have a high enough internal resistance to read a voltage due to inductance. An old analog voltmeter will not.
Regarding having the ground up vs. ground down, a lot of commercial electricians like to put the ground on top. If the ground is down and the plug works partly out of a socket, then a conductor that falls on the prongs could cause a direct short. On the other hand, a lot of customers are used to seeing a “face” on the plug and think that the other way is upside down.
I’m pretty sure there was a thread about this sometime back. I think the best logical explanation for this was: say you have metal covers, and a plug loosely plugged in, and the cover comes loose and falls onto the prongs of the plug. It would be better to rest against the ground prong instead of the other 2. I don’t recall if anyone was able to cite the code. (Now I’m thinking that someone said it was in some juristiction’s code book, but the book wasn’t online.)
I just had my 2008 NEC continuing education class, and the trainer specifically said that’s not a code requirement. However, most of the class (all three of us) seemed more knowledgeable than he was …
A requirement like that is more likely to be in the UL listing, or in the UL standard for the device. In that case, the applicable UL standard is UL 498, Attachment Plugs and Receptacles. I’ve not read that one, but if someone’s interested, I can check.
I would put my money on this. Your meter doesn’t have enough impedance to drop all the voltage across it because the open circuit is also high impedance (the voltage divider rule causes the largest voltage drop to be across the largest resistance which is usually the meter). Strange looking voltage readings like that almost always wind up being traced back to a loose wire somewhere. Finding that wire might be tricky. Start with the switch and the receptacle and work your way out from there.