Outside light loses power after a rain


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Old 08-14-06, 09:51 AM
T
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Outside light loses power after a rain

I have an outside porch light that loses power after a heavy rain, as does the entry light fixture inside the house which shares the circuit. No circuit breakers trip at the panel and there do not appear to be any GFCI's in the house that trip either. If one waits between 6 to 14 hours everything seems to be working again. I am thinking that there is some water that is entering the outside fixture which we are planning on changing anyway but can someone tell me why this is happening?

I thought if there was a water induced short that it would trip a breaker if not when the rain entered the outside junction box then certainly after I tried to switch the light on. Nothing trips and I do not reset anything- it just starts working again on its own?
 
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Old 08-14-06, 10:31 AM
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Something in that area is corroded and you should have every box opened and inspected. The light fixture, the wall switch, the entry light and any boxes that may be hidden in the crawlspace or attic.

What you have is very unsafe, and possibly a fire hazzard.

And no, when you drop an electric line into water the breaker will not trip, but enough current can flow to kill someone. That is why it is so unsafe.
 
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Old 08-15-06, 09:55 PM
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Originally Posted by jwhite
Something in that area is corroded and you should have every box opened and inspected. The light fixture, the wall switch, the entry light and any boxes that may be hidden in the crawlspace or attic.

What you have is very unsafe, and possibly a fire hazzard.

And no, when you drop an electric line into water the breaker will not trip, but enough current can flow to kill someone. That is why it is so unsafe.
Agreed... And by the way.... don't try the water electric thing.

Some things are best untested and untried. The dead guy... Take his word as GOSPEL. (there are better ways)
 
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Old 08-16-06, 07:36 AM
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Thanks for the sage advice. I have found that the outside entry light fixture had a plate that started to pull away from the siding, exposing the junction box and the lights connections. I have isolated the circuit breaker, it is shut off and I will replace the light and plate with something more waterproof. It was strange because it turns out that this same circuit has the utility room lights and the guest bathroom lights upstream (towards the breakers) from the exterior entry light and they never would lose power. I thought that if any portion of the circuit lost power or shorted that the circuit breaker would throw and I would lose power to the entire circuit.
 
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Old 08-16-06, 07:48 AM
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If a short occurs on a circuit and if that short allows enough current to flow to exceed the circuit breaker or fuse rating then the circuit breaker trips or the fuse blows(or at least it is supposed to).

However, if not enough current flows to trip the breaker or blow the fuse then you will simply waste power. More importantly, you may have a dangerous situation, based on where that current is flowing.

A portion of a circuit loses power because a connection opens. How much of the circuit loses power depends on how the circuit is run.

For example, if a circuit runs first to a utility room and then to a switch and then an outside light, an open connection at the outside light or at the switch for the outside light will only effect the outside light, it won't effect the utility room.

One possible explanation for your problem is that the outside fixture fills with water, weighing down the fixture, which puts stress on the wire connections, causing one to open. When the water eventually drains out, the excess weight is eliminated and the connections re-makes itself.
 
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Old 08-16-06, 09:51 AM
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Did you find actual signes of water damage? Corroded connections etc? Are you sure that this is the only box getting full of water? If what I suspect is true, the damage will be obvious and you will need to re strip and re make the connections.
 
 

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