Sudden Breaker Panel Issue

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Old 08-09-16, 11:29 PM
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Sudden Breaker Panel Issue

With every electrical thing in the house turned off, the panel functions as normal, 120v on each side. However, if you attempt to draw power on any circuit, that side of the panel will drop to 0v and the opposite side will register the entire 240v.

What would cause that to happen? Would a broken neutral connection at the meter explain it? The entire electrical system worked perfectly and then suddenly this!
 
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Old 08-10-16, 12:25 AM
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Actually you need to measure across the main breaker. It should read ~240 volts. If it reads~0 volts turn the breaker all the way off then on. If still 0v you need to call the electric company's 24-7 emergency service (not customer service) immediately. Turn off all 240 volt breakers till the problem other wise you could cause draw excessive current through 120 volt devices.
 
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Old 08-10-16, 12:53 AM
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I always have 240v at the main breaker TOTAL, and when nothing is in use, I have 120v at each main hot wire. BUT if I attempt to draw power through either of the two halves of the panel, the half I am attempting to use goes dead, and the entire 240v goes through the other half of the panel.
As in, one of the main hots reads 0v, the other 240v.
I know this is a very serious issue, all of my breakers are off and nothing is plugged in. What I'm wondering about is the cause and whether, based on these symptoms, the issue must necessarily be on the power companies side of things.
 
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Old 08-10-16, 01:29 AM
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Poco is free. Call them first.
 
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Old 08-10-16, 04:21 AM
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Poco = power company
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Old 08-10-16, 05:44 AM
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Thanks folks, I'll let you know what happens.
 
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Old 08-10-16, 11:38 AM
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The connection on the main neutral was failing in the pocos meter, but I'm back in business now, minus a few appliances that died in the initial surge. Thanks for the input, I appreciate it.
 
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Old 08-10-16, 12:04 PM
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Those symptoms are either a broken neutral, broken hot or failed main breaker but it can be difficult to tell which without some on-site testing. It doesn't matter that much from the homeowner perspective because in any case the power company has to be involved first to either inspect & repair or disconnect the incoming service prior to further work being performed. In some areas electricians can also do this diagnostic work, but in any case it's not DIY due to the always-live components in the service. It also varies around the country as to who owns and who is responsible for repairs on the various components of the service entrance.
 
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Old 08-10-16, 03:08 PM
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I always have 240v at the main breaker TOTAL
TOTAL? You don't add 120 + 120, you should measure 240 volts across the two main lugs at the main breaker.
 
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Old 08-10-16, 03:27 PM
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Yes, but with a broken neutral I always had 240 volts total across the main, but if power was being drawn on one leg, the voltage on that line would drop and it would increase on the other. Measuring 240 across the two mains wouldn't have alerted me to the broken neutral, but measuring one line at 0v and the other at 240v did.
 
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Old 08-11-16, 05:43 PM
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Broken neutral can damage your 120V devices.
What is happening is, since you don't have neutral 120V devices on one leg is connected in series with 120V devices on the other leg.
Devices using smaller current (less load) will show higher voltage then the devices using higher current. This means, it will supply higher voltage to a low current device and fry them.
Higher current devices are more likely to survive because without neutral, it won't have enough current flowing through.

240V only device will work as normal since they don't use neutral at all.
 
 

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