# Different Voltages on legs at breaker box



## bernie963 (Dec 18, 2010)

hi,

First turn off main breaker to prevent any damage from High voltage.

Second, call electric utility ASAP. Tell them your measurements under load.

You have a bad neutral, more than likely their problem.

Do it now!!!!

bernie


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## Big_John (Nov 15, 2015)

You lost your service neutral. Trying to run any appliances while this problem exists is a great way to destroy them.

The problem could be on your end or the power company end. You should talk to your electrician about an emergency call if the POCO says it isn't them because you should shut off your power until this is repaired.


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## MikeDobbs (Feb 27, 2012)

Thanks for the quick replies! I did shut off the power to the legs that were causing trouble while I waited for the POCO to arrive.

The guy said I had a bad neutral connection where the lines came to the house. I watched him pull the old end off the cable and splice in a new connector from the Neutral the the street line. That did the trick- everything seems to be working correctly.

Now I am trying to understand what happened. Can anyone explain to me how the neutral loosing a good connection results in the voltage differing between the two supply lines?


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## Big_John (Nov 15, 2015)

Normally the 240V coming to your house is divided perfectly in half by the neutral wire so all small appliances get reliable 120V.

When the neutral goes away suddenly the 240V gets divided by the appliances themselves. And unless the appliances use identical amounts of power, the voltage gets divided unevenly, so some things get a much higher % of the 240V.


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## micromind (Mar 9, 2008)

Picture a teeter-totter that's balanced, the left side is the same distance from the ground as the center and the right side. 

Now, put some weight on the left side. It will go down while the right side will go up. 

In this example, the 2 sides are both 120 volts and the center hinge is a broken neutral. As load is added to one side, its voltage goes down while the voltage on the other side goes up. 

Now, if we were to weld the center hinge solid, weight (voltage) on either side has no effect. The welded hinge is a solidly connected neutral. 

Rob.


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## bernie963 (Dec 18, 2010)

Mike, glad the problem is resolved. For the record it is a common problem and not unusual at all.

The neutral sets up as a reference point from which the two legs (both120v) are measured. the two legs are 180 degrees out of phase (to each other) to get the 240v total. If the neutral is compromised, there is no reference. the two legs still maintain 240v and all 240 volt loads will work property. The 120v loads will not always work correctly as there voltage will float because the lose of the neutral reference.

The see saw analogy is a good one.

Bernie


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