3-wire subpanel question

[Stevenfyeager]

Old sub panels in detached buildings had a 3 wire cable feeding them with a ground rod. I run into these all the time. I have to relocate a sub panel and have no choice but to continue using their same method. It bothers me that it does not meet modern code, having four wires. But I don’t know what else to do.

 

[roger]

As long as there is no parallel neutral path back to the main building there is not a problem. The reason for the new requirement is basically the potential for human error like adding a phone line or coax but since both of those are pretty much obsolete there is less of a chance now for parallel paths although not unheard of.

 

[electrofelon]

Old sub panels in detached buildings had a 3 wire cable feeding them with a ground rod. I run into these all the time. I have to relocate a sub panel and have no choice but to continue using their same method. It bothers me that it does not meet modern code, having four wires. But I don’t know what else to do.

IMO the old way is better, typically there is a larger fault path conductor with the 3 wire where it's a combo neutral and fault path conductor.

 

[Stevenfyeager]

As long as there is no parallel neutral path back to the main building there is not a problem. The reason for the new requirement is basically the potential for human error like adding a phone line or coax but since both of those are pretty much obsolete there is less of a chance now for parallel paths although not unheard of.

Thank you

 

[ptonsparky]

The common propane tank and associated copper pipe lines is there on occasion.