We bought an old pendant light for our flat, with a two prong plug. Rather than rewiring it in to the existing outlet, I just bought one of those $2 lamp holder outlet adapter. To be on the safe side, I checked it with my contact volt tester, which lit up when it came within a few inches of the unit (not even in contact).

I plugged the pendant in to a standard wall fixture and all was fine (no charge on the casing, the tester only lights up with contact on the cable). What's more, when I plugged our bedside lamp in to the ceiling adaptor the same thing happened - a good 2-3 inches out the fluke lit up.

Is there something about those outlet adapters which may be causing the pendant and lamp to be live? Or perhaps the ceiling fixture is rated too high for the pendant and lamp?

  • That's weird. Screw out the adapter and see if it happens when you put it close to the socket. If not see if you can trade the socket adapter for another one, or a different type. By the way, what kind of lamp(s) are you lighting up? Incandescent, LED, fluorescent, uranium...(:
    – lqlarry
    Feb 12, 2012 at 0:05

3 Answers 3


I would advise checking the wiring of the switch. It sounds like it might be a case of the switch for the lamp is switching the neutral instead of hot. The result of this is that when the switch is off, there is no visible light because there is no return path for the electricity (broken by the switch), but there is still eletricity making it up to the fixture.

  • I concur. This was my first guess as well. Feb 13, 2012 at 18:05

It is posible that when the house was wired the light fixture was not switched.The light was controlled with a pull chain.If a wall switch was added later they may wired the switch by breaking the hot wire inside the fixture mounting box.If that is the case you would have power in the box with the switch off.


Another possibility not yet mentioned would be that some kinds of light switches will 99.9% interrupt current but still let through a tiny residual amount. This is particularly true of electronic dimmers that don't use a neutral connection (many need a tiny amount of power for their control circuitry) and for self-illuminated light switches. When using such a light switch, it would be normal for an open circuit to read "hot" all the time, but adding any sort of load should eliminate that effect. For example, if you were to plug in a lamp then its power cord may read as "hot" when both the lamp and the wall switch are "off", but turning on the switch for the lamp itself should cause it to cease reading "hot" when the wall switch isn't on; turning on the wall switch should then cause it to read "hot" while also making the lamp glow.

If things behave as described here, especially if the wall switch is an electronic dimmer or a self-illuminated model, that would suggest that everything is fine.

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