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I'm getting readings of 120v and 81v alternating On one side of panel (call it A) and 120 and about 6.8 alternating on the other side (call it B) (all 2 pole 20 amp breakers to service 240 ). Obviously nothing working powered from this side. Some lights and low draw items work (intermittently) from 81v circuits on the other side. (A)

Have tried cycling the 200 main a few times and I would get "full power" for a few hours then eventually revert back. Ideas on why? Hoping just a 200 amp main breaker replacement...I don't think the q

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    Sounds like a loose neutral/bad connection. Quite possible it is on power companies side, from transformer to meter. Should have them check their wires/connections, especially if the wires are above ground.
    – crip659
    Oct 31, 2022 at 20:00
  • Are you making more of it than there is to the "alternating" thing? That just sounds like standard panel layout, which you'll need to learn. Here. diy.stackexchange.com/a/110152/47125. Also if the whole "2 legs/phases" thing is totally new to you, here youtube.com/watch?v=jMmUoZh3Hq4 Oct 31, 2022 at 21:31
  • Also since all your breakers are 240V, I think we'll need a pic of the interior of the panel. Are you sure it's not a 240V-only panel? Such a panel might exist for electric house heaters, often because of a separate metering for a special electric rate. Also if you're in the Philippines we'll need to know that, for reasons. Oct 31, 2022 at 21:33
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    @Harper -" Alternating ' meaning every other available 120 circuit . "B side" just happens to be all 240 - 2 pole breakers ....yes, zone electric heat. BUT, side A has a couple: well pump and dryer. Obviously, they also are not working. The 16 - 120v circuits are above. On This side every other circuit is 120v & 81v alternating including the 2 - 2 pole 30 amp breakers. As for the other side of the panel (all 2 pole 20 amp breakers) readings are 120v & 7 to 9v. This side alternating / every other 120 circuit. Oct 31, 2022 at 23:59
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    Yeah, I know it seems super obvious to you, but there are many arrangements of panel. All but Pushmatic follow the alternating stripes on a space basis but some also stack circuits per space so it gets super weird super fast. Also, can you measure the power input lugs at the top? Nov 1, 2022 at 2:06

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Most likely you have a loose hot either in your panel, the meter base or the PoCo's transformer connections. Powering down will allow the wire connection to cool, then when power is restored it starts failing again. We had the exact same problem a the parsonage next to my church, turned out to be bad connection in the meter base. Half the house would loose power and none of the 240v appliances would work.

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    Yeah, do mention that calling the utility should be their first step though, just as likely to be a problem on the PoCo's side as the OP's Nov 1, 2022 at 1:28
  • @ThreePhaseEel Good point in starting there. Generally a PoCo truck run isn't charged for. And those connections are exposed to the weather whereas in side a meter base or panel are not, unless there are serious leaks. Thanks for the comment. + Nov 1, 2022 at 3:18
  • @ George..pretty darn close George. Nov 2, 2022 at 15:21
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    @GeorgeEnded up being one side of the 200 amp main circuit breaker was trying to weld itself to the buzz bar. Hence all the crazy readings hour by hour. Nov 2, 2022 at 16:15
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Thabus bar in panelnk you for your help folks, I remembered this post and thought I'd use the format to help with diagnosis. With the information provided by systematically checking the entire panel. (And the buzing noise i heard in the process) led me to the main breaker. By removing it, the evidence was pretty clear..

the sketch of my process

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