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broke 05-01-2006 11:12 AM

Outdoor lighting
Does cabling underground corrode over time? We have light posts that don't work and were told that the wiring was simply put in the ground 30 years ago, instead of within 'piping', and that it has become corroded.

Wouldn't there be rubber insulation around the wiring?

Corrosion would happen pretty quickly wouldn't it ... so that even 30 years ago they would have insulated it in some way ... like with rubber/plastic coatings ...


inspectorD 05-01-2006 06:57 PM

It depends on where the wire a lake? Or what material was used? Was it direct burial cable or some old metal BX.
You should " call before you dig" or you may find other things in the ground,gas, water, septic or sewer lines, or other electrical wires.
But yes it can wear out over time.:eek:
Good luck with your project.

Square Eye 05-02-2006 03:54 PM

Yep, InspectorD's right-on. A tiny pinhole in the insulation may take many years to corrode to the point of failure. The type of wire and insulation, the composition of the soil, and the stability of the ground can all have an effect. Splices under the ground are always suspect, usually, a good electrician won't do a splice under the surface, but I've found a few over the years. When you replace the wire, if you use a UF or direct burial cable, lay a bed of sand first, then the wire, then cover that with sand. That way, if there are rocks or glass in the soil, they won't affect the cable insulation.

woodworkingmenace 05-02-2006 08:37 PM

I personally like to bury my underground cables in pvc, since it wont corrode, it will be water proof as long as you glue them up with sleeves, and put some duct seal where it comes up from the ground, or, if you run it all the way up, put an elbow so that the water cant get into the wire and still put duct seal in the opening... But, I leave the part, that is in the building with out ductseal, so that if any moisture would happen to get into the "run", I have it sloped so that it would drain into the house:)...

I also like it, because you wont readily "bust" through it, while digging, as you would an underground cable that is just "there". I put it through 3/4 inch line.

Oh, and I make diagrams that I keep in a "house book", as I like to do with all the "remodeling" I do, so that it can be passed on to the next occupants of this house, after the family has moved on. I hate it when you have to "guess" what is behind a wall, or what is underground...

Just my two cents for what its worth, and a wee bit extra for the collection plate...


broke 05-04-2006 07:57 PM

I like your methods Jesse -- esp the documentation.

So, I guess the wiring could just be bad in some areas. They claim the lights burn out quickly because there is bad underground wiring. They are also using ordinary house light bulbs.

I'm also wondering, leaving the top off of the bulb housing so that they can get rained on doesn't sound like a good way to keep the posts working -- esp if there isn't even a bulb in it. Wouldn't this be a problem?? as in they're supposed to be enclosed electrical areas ???

Sorry if the questions are dumb, but they just won't get the lighting corrected -- we are literally in the dark.

broke 05-04-2006 07:58 PM

P.S. I'm just trying to research things a bit -- not digging anything up myself.

woodworkingmenace 05-05-2006 12:00 PM

Well, there are a few facts...
If its a "Mercury bulb", (white light), they tend to lose thier efficiency very quickly over the years. As the Mercury in the glass tends to leak, or "gas out" quickly...

Sodium lights will last longer, but doesnt put out the white light, but an orange light, but will last a long time.

Any type of bulb, being hot, should not have cold water splashed on it. Even though the bulbs are in a "vacumn", the glass will crack after repeated cold spots on a hot glass.

I have seen regular bulbs used in glass enclosures. Or, if they have a large hood over them to protect them from the elements, (by hood, meaning a 4" hood all around, 8" diameter).

If you know where the "fuse" or "breaker" is for the light, then you can get a signal generator, (probably about 25 bucks or so), and unhook the wire, (after shutting the power off), and hooking up the signal generator to the wire and you take the wand and go along the ground and you can actually follow the line! I have one and love it! (I even use it to follor sewer lines, after putting down a metal snake, and attaching the clips from the signal generator to that!)...

Now, according to my Professor from Ohio Universtiy, the electrical current is on the "outside" of the wiring. So, if you get exposed copper, it turns green, and thus stops the flow of electrons because they cant travel in the green stuff, thus making an efficient barrier. Or, the flow is sufficiently reduced to stop it from lighting the light. Test with a volt-ohm meter. If its broke, due to expnsion and contraction of the soil, because its not burried deep enough and has been damaged by other things, as a piece of machinery too heavy for the wire to bear under a small amount of soil, then it will have been seperated (probably the copper and the wire sheath which will stretch can still be intact), and thus not working also.

Just some things to toss around and think about. Wires should be burried about 3 feet deep, (two feet very minimum), and marked. They suggest to leave a "barrier" of signs one to two feet down, before you hit the lines, as a warning. (This barrier is just a tape with the words underground lines along it)...

Living next to an electrical contractor store, (which I frequent, because of the friends I have made there and as a customer), I get to talk to contractors, and learn a lot from them and the store employess.

Just my two cents for what its worth, and a wee bit extra for the collection plate...


broke 05-05-2006 07:35 PM

how about having the top off and no bulb in and the socket getting rained and snowed on?

woodworkingmenace 05-05-2006 08:01 PM

Well, the socket is facing down... Unless there is a "high humidity" area, the socket should be ok. If you have "rust" in the socket, then its time to replace it, as it will short out, or not function at all. Electricity has a tough time getting through rust also.


broke 05-06-2006 09:41 AM

oh, i see, facing down, i'll have to look in there.


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