3 WIRE 480 VOLT PROBLEM

[bure961]

If a ground system activated on 3 wire 480 service would opening the main service breaker determine if the cause is on the poco end? Is there more to it ? Never came across this type of service . Thanks for your help in advance.

 

[LEO2854]

If a ground system activated on 3 wire 480 service would opening the main service breaker determine if the cause is on the poco end? Is there more to it ? Never came across this type of service . Thanks for your help in advance.

Can you post more information on that?:blink:

 

[augie47]

Most likely your ground monitor is on the load side of the service disconnect and opening that would simply turn the monitor off.
Normal procedure would be to turn off feeders to see which one had the fault, then individual branch circuits to further define,.

 

[kwired]

Ground fault monitor would detect and indicate a fault anywhere on the system including ahead of the service disconnect, but as Gus said opening the service disconnect would remove power from the detection system. If you turn off all feeders and still have a fault indicated the chances of the fault being ahead of the service disconnect are looking fairly high.