Testing security light socket

elwopoMay 8, 2012


I have a dusk to dawn light that's not working and tried to test the socket. Covered the sensor. Used a multimeter. When I put the black on the center and the red probe on the socket threaded part, the digital numbers on the meter jumped around like crazy. When I switched the probes (red on center and black on threaded part) same thing happened.

First, which is ground on a socket and which is hot?

Second, why are the numbers jumping all over the place?

I tested the multimeter by putting the red in a receptacle slot and the black in the ground prong hole and it read 124.5 so I'm guessing the meter is working correctly.

Any help appreciated.

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Ron Natalie

Normally the threads on the socket is connected to the grounded conductor and the button is hot but you can't rely on that. The "jumping around" behavior is indicative that the probe is connected to a conductor that is connected to neither a ground nor a hot. You're seeing a lot stray inducted values. They can be quite large but have next to no current to them.

The first thing to look for is if the wires leading to the photocell have any power (then look for a breaker, a switch, or some poor connection if not).

    Bookmark   May 8, 2012 at 6:27PM
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My sensor burns out about every three years because it faces into the sun. You might be suffering from the same ill. In my case, it's easier to just replace the sensor than try to re-orient a pole that's buried in concrete.

    Bookmark   May 8, 2012 at 9:45PM
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