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glinka 07-22-2011 10:40 PM

Still power
I have a flourescent light plugged into an outlet, outlet controled by a switch. When I turn the switch off the light goes off, but you can see it glow slightly on the ends. I have a cheap tester that lights to show if there is power and it lights when put in the outlet and switch is off. What to do?

gatorfan 07-23-2011 08:32 AM

Two guesses:
  1. Hot and neutral are reversed in the outlet. Easiest way to test is with something like this. Or test with your light tester vs. ground.
  2. You're switching neutral instead of hot at the switch. If it was done right the neutrals would be reidentified like this. You could also test at the outlet to see if hots always stay hot vs ground despite the switch position.

kok328 07-23-2011 08:59 AM

On & Off is being looked at from a relative point of view. In other words, down is off and up is on. Has the switch been installed up-side-down ?

JoeD 07-26-2011 07:13 AM

Is the switch lighted? Lighted switches pass a small current to light the switch.

gatorfan 07-26-2011 07:32 AM

Guys, reread his/her question. It's not that the light is completely on when the OP thinks it should be off, nor is it that the switch is lit. The OP says the fluorescent bulb is "half lit" with just the ends lighting up when the switch is off (and, I assume, on regularly when the switch is on). When fluorescent bulbs do this (when switched on) it usually means the ballast needs to be replaced.

In this case, since it's happening only when the switch is off, I think there is an unswitched hot going to the fixture. So, the switch seems to operate almost normally, but it's really switching neutral (because the switch is on the wrong conductor). If this is the case, a small amount of current could be leaking to ground in the fixture when neutral is "switched off", enough to cause the bulb to "half activate."


glinka 07-26-2011 08:58 AM

I tested, as gatorfan suggested, hots versus ground with switch off. It is always hot. Is this OK or not?

gatorfan 07-26-2011 09:47 AM

No, it's definitely not OK. Your ground wire is carrying current. Obviously this means you are using power all the time, but it's also dangerous since the ground path is energized. Since the frame of the light is grounded, you could get a shock if you were in contact with it and something else grounded (like a faucet).

So, you need to find the hot leg and move your switch to it. Check out the switch box. If you're lucky, both hot and neutral come into and go out of the box. Someone has wired neutral through the switch and hot just passes through. You want to swap that, running hot through the switch and wire nut the neutral back together.

If one receptacle is switched and the other is always on, you probably have a three-conductor (four wire) cable from the switch box to the receptacle. Normally you would pigtail your black to one side of the switch (and pass it through to the unswitched receptacle) and use red to the switched receptacle.


glinka 07-26-2011 09:55 PM

The line continues from switch box to gfi plugs. White, neutral is connected to switch, gfi plugs have power all the time. Could there be any reason for neutral to be to switch?

gatorfan 07-27-2011 07:54 AM

1 Attachment(s)
Let me make sure I'm clear on my terms and separate the purpose of the wire from the marking of the wire/insulation.

I know of no reason why you would switch neutral. Neutral should always be on a white wire (unless > 6 AWG) but a white wire may not always be neutral. You are permitted to reidentify a white wire as a hot (normally with either a wrap of black electrical tape at both ends or a sharpie) if it's part of a cable or > 6 AWG and you have a reason to do so. An example of when you might do this is if the switch was after the outlet in the circuit (see here for a diagram). In this case, although the insulation is white (remarked as a black) the wire is actually functioning as a hot since it's between hot in the panel and hot at the outlet.

I redrew the diagram from the above-linked site to make it a little simpler. Current moves clockwise:


TxBuilder 07-27-2011 08:55 AM

Nice illustration. Looks good.

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