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I am 90% sure I am losing power to one leg. Unfortunatelly, I have not had an outage since I discovered that three breakers on the same leg were un-tripped and losing power (5.7v on each). I initially thought it was one "bad" breaker and after power returned I cut the main breaker, removed the wire which looked good, scraped to get shiny copper, applied a dab of DE-OX and reattached. All of the wire screws are tight and the box looks good. After the power went out a third time I checked the internet more thoroughly for multiple breakers losing power. It may be my service line shown in the attached photo which I should fix as I get severe salt air. Is it likley to be the service line? I need to do a little more research before I try to check continuity between the frayed service line and the problem power leg. Any additional comments. Thanks enter image description here

  • I'm the last guy to jump on the "torque screwdriver" bandwagon, but when dealing with something as shady as a Zinsco panel, you want the torques to be right. – Harper - Reinstate Monica Feb 24 '20 at 17:38
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First off, look at your weatherhead. That funny little gooseneck the powerlines go to. There's a crimp there on each wire. The crimp, and everything between the crimp and the pole, is the power company's bailiwick.

You can't really measure there, but you can measure at the top (line side) of the main breaker.

Turn off the main breaker to prevent crosstalk and feedback from influencing results. Now measure

  • From Hot L1 to Hot L2 (should be 240V)
  • From Hot L1 to Neutral (should be 120V)
  • From Hot L2 to Neutral (should be 120V)

If that is solid, then turn your main breaker back on, and turn off all breakers that are 240V, or handle-tied, or have a red wire going to them. (Zinsco is unique in that a "duplex" double-stuff breaker can actually be a 240V breaker; that is the only panel capable of that trick.) 240V loads will contaminate test results, because they are a resistance between the two poles.

Now, check the numbers again.

If you see the 240V number being less than 240V, that is a lost hot wire. If you see any 120V numbers being above 120V, that is a lost neutral. You can limp along with a lost hot, but a lost neutral is a true emergency. Turn everything off ASAP!

If you see any lost wires, call the power company and report an outage.

We have field reports of the power company discouraging people from reporting outages, by cross-examining you with questions like "Do your lights work"; their job is to screen stupid people to avoid false service calls. If the above tests prove an outage, then you need to "lie" your way past the gatekeeper and get the truck out there. It's not a lie: the outage is real, it really is in their bailiwick, and your lights really are out because you tripped the breakers to prevent damage.

When the truck is out, be sure to point out this damage you show here. I have a feeling the pole-top splice may be in equally deplorable condition, and if it looks bad, the lineman could potentially fix it, call the job done and drive away, leaving this one unnoticed. Don't let that happen. Meanwhile stay away from it.

  • Look at the right splice it is failing. The numbers may be ok right now but the failure is obvious. – Ed Beal Feb 24 '20 at 18:04
  • @EdBeal Oh, I don't doubt it. But you have to wonder if the pole-top splices aren't equally bad. They all need replacing and the PoCo should do them all, cheaper than 2 service calls. – Harper - Reinstate Monica Feb 24 '20 at 18:09
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I installed hundreds of zinsco’s back in the 70’s I loved them, I always used deox on the buss bars as they were aluminum. Today when inspecting a panel I look for arcing if no arcing I replace the breaker with some deox and this has been satisfactory for insurance carriers. If there is any and I mean any arcing both the position and breaker are bad! No exceptions! If the panel is full it has to be replaced. If there are available slots and breakers some minor surface burns no pitting the panel has been ok with one insurance carrier (I suggested it should be replaced)

I see damaged insulation on that service but the insulation damage could be from heat from a bad splice on the right, I would send this photo to your serving utility. I do not think your panel is a problem,

I believe the bad splice is the problem and the heat created is causing more damage. I would want to get this repaired sooner than later with this photo and a report of failure my utility would be there right away to repair it.

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    Since I posted this my power went out again and both cables to the main breaker measured 123 volts but one bus bar was no voltage (all breakers off). Seems that the bus bar under the main breaker is bad and it is too hard to remove any breakers. I can use a lot of force to jiggle the main breaker around and get power to come back on for the 20 amp breakers can Also the main power line needs repair but replacing my panel is the first item Thanks for all the great help. I love this site:) – HWS Feb 24 '20 at 21:50
  • Did you turn off the main or as @ Harper said the 120 may be reading through a load that is providing the voltage on the dead leg. Time for a panel update if you did turn things off. I would have bet $ on the leg having a bad connection. – Ed Beal Feb 24 '20 at 21:54

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