electrical trouble shooting

[wjkrostek]

I have  two small grain bins that I can't seem to get power to.  They ran for 5 years but something must of happened.  I have a under ground 0 cable from the house to a barn  then to another barn then out to the bin. I can't seem to get my head around whats wrong.  I can get a voltage reading at 120 but not enough power to run any thing.  so I thought maybe there is a break in the undergound cable.  so I checked to see if the power meter was turning faster  because of leakage to ground.  but no change with the breaker on or off.  If there was a break woundn't there have to be leakage and loss of power.  I pulled the breaker and checked it with a VOM and it seems it Ok.  I took a 12 volt battery and hooked it up to the two power cables  back to the barn and I have 12.7 volts after a run of 100 ft.  So that tells me the wires must be OK.  What Am I missing??  There has to be something simple I'm missing???????? Any ideas will be helpful. Thanks 

[rawhide]

sounds like you have lost one leg of your 220 in one of those barns. make sure all connections are tight

[wjkrostek]

My motors are only 120, the 2 bins are just 1000 bu bins and the fans are just 3/4 horse fans.  Although the voltage on the VOM reads 120 there is not enough power to run a shop vac I was try to use to clean out the bin but I can hear a  low hum from the shop vac.  One leg I lost last year to one of the bins but didn't need that bin so it wasn't important at the time now I lost the other one.  I'd like to get them both back up but just can't  seem to understand.   Everything I check seems to say it should be working.  Is it possible to have a breaker go bad but  it still  looks like its OK with a VOM?  Can a wire break and still show 120 volts but not be able to move some amps? There is something I'm missing but I just can't get it.  

[dave.charlesworth]

You most likely have a loose connection somewhere. It will allow enough amperage through to read 120 volts on your meter but will not give you enough amperage to run any motors. Or the connection could be corroded,this would increase the resistance through the wiring. 

[wjkrostek]

I got a new breaker today but no change.  Any resistance problms should show up as heat I would think.   Wouldn't a cable break have some leakage to ground making my meter spin faster? when I hook up a 12 volt battery to the power cables I get the 12.6 volts at the other end of the cables. wouldn't that mean the cables are fine?  everything seems to be tight. something here I'm not seeing.  I'll hped to find the problem to keep me from digging up the cable.

[buckfarmer · Accepted solution]

I think you have lost ground somewhere. It can be tough to find. Happened once to me and was actually on the pole. Could also be a lost leg of your 220. Had that just this spring. Even though you are only using 120 you still need 220. To make each leg of 120 work. Mine was at the transformer. Some of my 120 outlets worked some did not. No 220 worked. I'm sure an electrician could explain the how and why of what I'm trying to explain. Most of my experience is with three phase, which is accually easier to troubleshoot.

[wjkrostek]

Well I pulled out the line and half way between the two barns I found one leg and the ground totally corroded and gone for about 4 inches. All at the same spot.  Insulation  almost looked like it was cut all the way around but it wasn't clear what could of done the damage.  It is not in a spot I drive on or park any thing.  So I will never know.  I think it must of  been the frost heaves and a small crack let some water in.  I live in a frosty place.  Still found some Ice when I dug about 6 inchs deep.  I just can't believe I got any readings when I was checking as bad as the break looked. the ground didn't look burnt or even dry where the break was.  This stuff is just  a lot harder to trouble shoot than I thought it should be or should be.  Thanks for everyone's help in trying to think this out.  Live and learn.

Bill