Lamp post photo cell
 

A neighbor has asked me to check out her outdoor lamppost. The light never comes on. We have done the obvious; change bulb, check breaker.

I told her I would get and replace the photo cell for her. After I told her that I started thinking about the ones I have replaced for others in the past. Those have always failed in such a way that the light NEVER shuts off.

He light never comes on. Can they fail that way also, or should I have her hire an electrician to diagnose?

Check the bulb socket. Mine somehow gets insect debris in it and I have to clean it about twice a year. I just turn off power and clean it real well with a small wire brush.

When that happened to us, it turned out the cable to the post had been damaged by rusting around the hole in the post where the cable enters the post underground. They had to remove the post, place some cushioning around that opening, and reset the post. Fortunately, there was enough extra cable from the breaker box to the conduit that they didn't have to re-wire the post.

The suggestion is to test for power to the post at the photocell. As you said, when the photocell fails, it leaves the light on all the time.

Lamp post
 

Same happen to me.I replaced the sensor and all works well.My breaker box was not marked for the lamppost so I needed to shut down the whole house to do the replacement.I would advise you to do the same and not trust the label on the breaker box.Once the light is you can verify if the label is correct.

A photocell failing lives the light on longer . to replace mine i tripped circuit breakers until I found the right one. Prior to searching for the breaker I covered by photocell with black tape so it came and stayed on. The replacement was simple

I believe the post lamp is on a GFCI circuit, so you may have a tripped gfci device.

and the answer in this case is....
 

It was the light sensor (photo cell) switch in the lamp post.

I do not do this for a living, so I do not see a lot of failures, but this is the first one I have seen fail 'open'; by open I mean the light never comes on.

Thanks for the insights, $7 and a happy neighbor....

Glad you were able to help the neighbor, I tend to do the same. I was just going to reply that the photocell units can fail either open or closed, but I see you have already solved the problem.
Good for you.

Everybody might be wise to flip a few breakers when there is no problem, and mark the one that controls the circuit for the post lamp......just sayin.

Due to the fact her light was not working I could not visibly verify the breaker. My plan was to just shut the whole panel off. I started the work during the power outage yesterday, so there was minimal impact :)

It was nice timing that the power came back on just after I had finished securing the new sensor. That let me test the light before putting everything back together.

So, you're the guy to blame.

What I actually meant was to identify the circuit before there is a problem, so you can turn it off to work on it. I am going to mark mine this morning.

I understood, I should have prefaced my post with that is a good idea :thumbup:

There is an illogical paranoid part of me that still wants to see the light go off when I flip the breaker; so even though I KNOW it is the right one, the illogical paranoid part of me would still shut off the whole panel if I could not verify. Not saying that is correct, just pointing out a personal flaw :loco:

At our house in Georgia the photo sensor died at least twice in ten years and failed to turn on the light.

Ours here in TV is now broken with the same light off.

I think Harbor Freight (possibly Radio Shack if you can find one), and some other stores sell voltage sensors, these emit a beeping sound when they come close to an energized wire. I have one that I use when I need to make sure a circuit is de-energized before working on it. I also have AC voltmeters, but the sensor does not require any connections, and is easier to use.