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Discussion Starter · #1 ·
Our children recently bought a small acreage with a barn that gets its electrical service from the house. The service in the house appears to be fine. The barn has a six-place panel, and we noticed that breakers on only one leg (places 1, 3 and 5) are being used. Outlets connected to breakers on the other leg (places 2, 4 and 6) don't "work". The multimeter shows proper voltage at the panel -- 120V between neutral and either L1 or L2, and 240V across L1 and L2. It shows proper voltage when checked at each breaker connection. The outlets connected to breakers 2, 4 or 6 show 120V at the outlet but devices plugged into them don't work.

The only thing I can think of is that the double-pole breaker in the house that sends power to the barn is malfunctioning? Is that the most likely explanation? Are there others? Thanks.
 

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Discussion Starter · #3 ·
The barn panel includes a double-pole breaker that occupies Place 1 and 2; it shows 240V across the two pole connections. If we connect the breaker on Place 1 to an outlet circuit, the outlets work fine. If we connect the breaker on Place 2 to an outlet circuit, the multimeter shows 120V at the plugs but they won't power anything.

What might be wrong with the barn panel that would make it behave like that?
 

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If you are getting 240 volts in the barn the problem is right there in that panel

Not necessarily. I think you have a loose connection somewhere between the 2 panels. With no load there is power, but as soon as something tries to draw a load, it disappears. This is a somewhat common issue.

Plug something in and then check with your voltmeter to see if you still have 120V from Line to Neutral once you plug something in. If the voltage disappears keep moving closer to the panel in the house until you find out where you still have the power.

It could very well be a bad breaker in the house panel like you suspect, or it could be a loose lug at that breaker or in the barn panel, or a loose wire nut somewhere, or maybe something has chewed mostly through the wire somewhere between the house or the barn. Hopefully it won't be too hard to track down and rectify.

Good luck.
 

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The barn panel includes a double-pole breaker that occupies Place 1 and 2; it shows 240V across the two pole connections. If we connect the breaker on Place 1 to an outlet circuit, the outlets work fine. If we connect the breaker on Place 2 to an outlet circuit, the multimeter shows 120V at the plugs but they won't power anything.

What might be wrong with the barn panel that would make it behave like that?
When you are checking the outlets are you checking to neutral or ground?

Tighten the screws holding the neutral wires?
 

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When you are checking the outlets are you checking to neutral or ground?

Tighten the screws holding the neutral wires?

He says that the neutral works with the other half of the breakers that aren't having a problem, but I agree that it is a good idea to check that all of the screws (and wire nuts) are tight everywhere.
 

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Measure the voltage to neutral while turning on some high draw devices like heaters. Is the voltage stable?
 

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Discussion Starter · #8 ·
One thing I neglected to do was check the voltage at the outlet with something plugged in. They have a 120V heater for de-icing stock tanks that we used as one of the devices to determine whether the outlet was functioning -- I really should have measured the voltage at the outlet with it plugged in. Will try that before going any further. I cannot imagine that it won't draw the voltage down to essentially zero ...


Thanks for the suggestions. I'll come back with either more questions, or (hopefully) a description of what was wrong.
 

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check the voltages at both ends and compare
measure at main panel and again in the barn
this should tell you where the problem lie's
Faults in the cable between are common,
especially if they are underground.



:vs_cool:
 

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Discussion Starter · #11 ·
It would appear one of the services lines has failed. When I put a load on that leg, voltage to the barn panel on that leg drops to zero, but it reads normal at the breaker in the house. The line is buried and is aluminum. My electrician tells me that if water collected in the buried conduit and the insulation was compromised, the line can essentially dissolve over time. Who knew?
 

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If a buried aluminum line has its insulation compromised or chewed by an animal then it is not unusual for the aluminum conductor to corrode into a white paste and still give close to proper voltage with no load and close to zero volts to neutral at the downstream end when loaded.

Corrosion this severe rarely occurs with copper conductors in less than several decades but could occur with aluminum conductors in only a few years after the conductor got wet.
 
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If a buried aluminum line has its insulation compromised or chewed by an animal then it is not unusual for the aluminum conductor to corrode into a white paste and still give close to proper voltage with no load and close to zero volts to neutral at the downstream end when loaded.

Corrosion this severe rarely occurs with copper conductors in less than several decades but could occur with aluminum conductors in only a few years after the conductor got wet.
Thread sounds familiar. Lost all power in my separate garage. Everything dead at the sub.

Discovered 2nd previous owner had run #10 aluminum underground from the main (20' under soil and 28' under slab). Finally after much investigation (being a novice), concluded that the aluminum wire had shorted underground.

Simplest cure was run 100' of new 10 UF copper underground from pole to near side of garage, then through the wall and overhead from there to sub.

And yes, the aluminum wiring was probably around 30 years old.
 
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