??? - Puzzler - ??? What might cause no voltage reading between phases?

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Coastal

Coastal

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Kill Devil Hills, NC
Help me figure this one out. I have a 150 Amp main breaker disconnect being fed from the meter socket. SER is feeding from the main lugs of the disconnect to a 150 amp main breaker sub panel in the house. I get 240 volts across phases at the main lugs of the disconnect, as well as 120 volts to nuetral and ground. In the house panel, I get 120 volts from each phase to neutral and ground but nothing between the two hot legs. What could possibly be happening to the feeder between the disconnect and the sub-panel to be causing this?
 
Coastal said:
Help me figure this one out. I have a 150 Amp main breaker disconnect being fed from the meter socket. SER is feeding from the main lugs of the disconnect to a 150 amp main breaker sub panel in the house. I get 240 volts across phases at the main lugs of the disconnect, as well as 120 volts to nuetral and ground. In the house panel, I get 120 volts from each phase to neutral and ground but nothing between the two hot legs. What could possibly be happening to the feeder between the disconnect and the sub-panel to be causing this?
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Something happened in the connections from the sub panel to the house panel and resulted in the same phase being present in the hot legs of the house panel.So check in the sub panel for this condition.
 
Yup.

Or, one hot leg has failed open in the SER run. At the failure in the SER the line side is simply not in contact, and on the load side, the failed conductor is shorted to the other hot conductor. (Nail, screw? Or a saw cut into the SER?)

Another possibility: One leg is simply completely open, and the 120 volts that you are measuring on it is the bleed through from the other leg coming through the 240 volt loads.
 
You lost one phase from the main disconnect to the subpanel. You could be getting a full 110 volt reading on both phase at the subpanel from a few causes.
 
I agree with the above post.

You have lost either line 1 or line 2 feed to your sub or load center in your house.
A way to verify this would be to turn all your branch circuits off in your load center in the house.


If this leaves you with just one hot line it is a break in the dead line.

Ronald :)
 
Use a wiggy (solenoid tester) and take the same measurements. It puts an actual load on the circuit and won't read any bleed through of the circuits. I carry one just for these types of troubleshooting calls. I'll bet what you will find is one phase is dead.

Good luck
 
paul said:
Use a wiggy (solenoid tester) and take the same measurements. It puts an actual load on the circuit and won't read any bleed through of the circuits. I carry one just for these types of troubleshooting calls. I'll bet what you will find is one phase is dead.

Good luck
Click to expand...

Gota go with this, always double check with a solenoid tester!
 
What Al said.

paul said:
Use a wiggy (solenoid tester) and take the same measurements. It puts an actual load on the circuit and won't read any bleed through of the circuits.
Click to expand...
It will help with phantom voltages but I'm not so sure about the bleed that Al spoke of. What is the impedance of the solenoid tester as compared to a 240 volt load like a stove, etc? I think I read the solenoid testers were around 2-4 kohms so it would still probably indicate 120 volts.
 
Coastal said:
Help me figure this one out. I have a 150 Amp main breaker disconnect being fed from the meter socket. SER is feeding from the main lugs of the disconnect to a 150 amp main breaker sub panel in the house. I get 240 volts across phases at the main lugs of the disconnect, as well as 120 volts to nuetral and ground. In the house panel, I get 120 volts from each phase to neutral and ground but nothing between the two hot legs. What could possibly be happening to the feeder between the disconnect and the sub-panel to be causing this?
Click to expand...

The voltage readings you were getting, were they on the line side or the load side of the main? Check both sides of the breaker, see what you get. may be a bad breaker.
 
Thanks for all your help! The readings (or lack thereof) came from the line side of the main breaker and the culprit is a bad line feed from the disco to the sub in house.

Thanks again for the help!
 
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