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In my folks old farm house, at the panels main input from outside. L1 is 130v. L2 is 112v. When a load is applied both legs down voltage, allot! Anywhere from 10 to 20v.

The wires running from the pole outside to the house are old and exposed.

Could the old wires cause the difference between L1 and L2? If so please explain why/how?

Thank you in advance for any input I can receive!!!

ArchonOSX
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Darrell Smith
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  • Why did someone VTC for "product or service recommendations" ? Anyway, do your lights get brighter when you pull a heavy load? If yes, see Tester's answer. – Mazura Apr 14 '16 at 04:25
  • Thanks so much for this post, I was having voltage fluctuations in my house, lights would flicker, microwave would slow down, etc. I tested both lugs coming into my house and one was 156V under load and the other was 104V, I called utility company and they sent someone out the same day and repaired the neutral coming to my house which solved my voltage problems at no charge to me. Thanks again for the great post and answers. – Mojobaby Oct 21 '18 at 14:27
  • I'm having this same problem even after the electric company replaced the main wires coming from the transformer to the house. Time to call the electrician... – Freddie Apr 02 '19 at 16:20

5 Answers5

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Sounds like you might have a bad neutral. Contact the utility, and have them check it. This is a dangerous situation, that need immediate attention.

Voltage swings can wreak havoc on sensitive electronics, so you may want to use UPS to protect them.

Tester101
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This is a "lost neutral" and it is very dangerous and should be dealt with swiftly.

Your house has 240V power with "neutral" in the middle. That gives you two sides. The neutral from the transformer forces each side to be 120V. What if it didn't? Then each side would be "whatever" in voltage! (but they would add up to 240V.) That is happening.

The connectors/terminations are far more likely to be the culprit than open runs of wire.

That "whatever" will change with load. Turn on a toaster on one side, its voltage will drop and the other side's goes up. You're bound to over-voltage both sides and blow almost everything in your house... and that can start fires.

What's more, your neutral may not be at a safe (near ground) voltage anymore. Even scarier, some electric ranges and washing machines attach the chassis of the machine to neutral because they are too cheap for proper grounds. With a lost neutral, those chassis are now hazardous. People have died from this. Recently. Google "electrocuted" and that's usually the story. You can't cure this by turning off the breaker; breakers don't switch neutrals.

enter image description here Source

Here's how a common panel is set up. Notice the two hot buses (copper) - those fingers that stick into the middle feed the breakers on both sides. Notice the trick so each hot bar serves every other row of breakers. Got it?

I would normally say "Turn the main breaker off NOW and don't touch it until it's fixed" but that will result in a fridge full of lost food, and one may be reluctant to do that. One way to temporarily cope with a lost neutral situation is to choose one of the two buses and turn off or pull every breaker that attaches to it. (on most panels: every other row). Now one phase is irrelevant, you have turned your panel into a 120V panel: if neutral goes out, power simply fails, but nothing goes overvoltage. Now instead of being a spooky goblin that fries things randomly, it's a plain failure. Much easier to troubleshoot. However, when power goes out, your neutral wire may be pulled up to 120V... and formerly benign contact with neutral (like those neutral-grounded appliances) is now deadly. Fix this ASAP.

Harper - Reinstate Monica
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The age of the feed wires won't cause this. It is the connections that cause problems.

Double check your main connections to make sure they are tight.

This is very dangerous so the power should be shut off first.

It sounds like you may be dropping voltage across a high resistance connection at one or more of the main terminals.

If the wire is aluminum it may have oxidized and created the high resistance condition.

Good luck!

ArchonOSX
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OMG! This would scare me if it happened. Quit using ANYTHING using either of those legs. Bad Neutral connection, You may easily electrocute yourself. You see as the post above mentioned some appliances rely on a ground that they don't have. Otherwise yes, pick a phase and shut it down. Call your electrician Now and see about having neutral bad. If your lucky it is bad on transmission (the ground at the transformer and you cant be charged for it.) Whatever, just get your electrician as this is probably hard on everything you have plugged in,BTW... check your wiring for the neutral, if it is oxidized than that is what needs replaced as ground requires very little resistance for the given voltage to be able to earth the current flowing. Good luck, hope you get this figured out.

user91521
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BTW... check your wiring for the neutral, if it is oxidized than that is what needs replaced as ground requires very little resistance for the given voltage to be able to earth the current flowing. Good luck, hope you get this figured out.

user91521
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    Can you edit your post above and merge this with that one? – ThreePhaseEel Sep 27 '18 at 03:51
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    Hello, and welcome to Stack Exchange. The goal for our Q&A format is to create a best answer for each question. So, as @ThreePhaseEel suggests, please work to make one of your two answers have all the information that an answer needs, and delete the other one., – Daniel Griscom Sep 27 '18 at 14:15
  • sorry, err.. how do you delete a answer very sorry. I am new here and am not to sure how the UI works. – user91521 Sep 28 '18 at 00:00
  • @user91521 -- look below and to the left of the text of the answer, there should be a "share edit ..." that includes "delete", but make sure to edit your answer above to incorporate the text of this answer first. – ThreePhaseEel Sep 28 '18 at 00:12
  • Well done, now just hit delete on this one. – Harper - Reinstate Monica Sep 28 '18 at 01:20