electricity on/off

1. Lines were shorted for example a squirrel or a branch went across two hot lines or a hot and a ground. That system was intentionally let the short remain in effect for several seconds in order to try to burn through the offending object during which time all loads on the circuit get very much reduced voltage and after which time the power goes back to normal.

But I think that the system breaker will trip (or a fuse up on a utility pole may blow, usually with a super loud pop) long before 40 seconds. Then the power company needs to send someone out to find the fault, remove it, and reset the breaker manually.

2. There is a damaged wire or loose connection at your house, or up on a utility pole, that breaks and re-makes in the wind.

Fault -- Situation, such as wires touching that should not, allowing an unwanted current flow.

3. Sometimes the POCO will intentionally remove power (somewhere in the distribution/transmission grid), in order to re-route power around a fault.

1.deleted

Thanks for the info.It did it again more randomly and faster.. was like the light was loosing power as it went out.
Found out many street lights were out in area so im assuming it was related to an outage due to very high wind.Is it always best to shut off main breaker when this occurs again? I have never seen this much fluctuation in incoming power in many years.
(i had told them about it once it started-POCO)

Have you called the POCO and told them about it? I would.

It is caused by Recloser http://en.wikipedia.org/wiki/Autorecloser "In electric power distribution, a recloser, or autorecloser, is a circuit breaker equipped with a mechanism that can automatically close the breaker after it has been opened due to a fault.[1][2] Reclosers are used on overhead distribution systems to detect and interrupt momentary faults. Since many short-circuits on overhead lines clear themselves, a recloser improves service continuity by automatically restoring power to the line after a momentary fault."

Next time it happens call the POCO and tell them what you saw, whether it be just your lights or those outside as well. At any rate they need to know and take care of it. I had a similar situation many years ago when I had overhead lines...it turned out one of the connections on the wire had loosened over the years and strong winds moved the wires around enough to open up one of the incoming legs. The POCO came and trimmed a tree and replaced the compression connectors.

Did that have any effect on your end of the electric,from panel inside through home?

Other than the annoyance of some things not working at times, no damage.

Reclosers are 3 strikes and you are out.Not a random time.

Dependa on how they are set up Bob. Not all are three strikes. Also with high winds, it can cause the reclosure to act like it is supposed to. Which means that it can do what the OP was stating.

A lineman explained to me once the recloser will try three times then stay open. So if you see the power blank couple times on the third try you will be dark.