Old service on detached garage.

[Hendrix]

There is no equipment gnd. from the disconnect inside the garage to the "sub panel" inside the
house.
How would you ground new circuits inside the house?

 

[kwired]

There is no equipment gnd. from the disconnect inside the garage to the "sub panel" inside the
house.
How would you ground new circuits inside the house?

Before 2008(?) NEC you could could run three wire feeder to a second structure and ground the neutral at the second structure. Exceptions since the change still allow for that in existing installations, but run a new feeder and you need to pull an EGC.

 

[Dennis Alwon]

I would treat it as a new service. The neutral should be bonded to the can and ground rods driven and wired to the same bar. All neutrals and equipment grounding conductor should be tied together in the panel

 

[Hendrix]

Thanks, I thought it should be treated as new, but wasn't sure.

 

[kwired]

What is meant by treating it as new? Requiring a separate EGC from the neutral?

If it was existing before 2008 NEC was in effect there is nothing wrong with it unless there is other conductive paths between the two buildings which would end up being parallel with the neutral. This is permitted by exception 1 250.32(B)(1) If you were to change the service at the garage or to change the panel at the house you can still use that existing feeder and not pull the additional EGC. Now if running a new feeder to the house then the exception no longer applies IMO.

 

[Dennis Alwon]

What is meant by treating it as new? Requiring a separate EGC from the neutral?

If it was existing before 2008 NEC was in effect there is nothing wrong with it unless there is other conductive paths between the two buildings which would end up being parallel with the neutral. This is permitted by exception 1 250.32(B)(1) If you were to change the service at the garage or to change the panel at the house you can still use that existing feeder and not pull the additional EGC. Now if running a new feeder to the house then the exception no longer applies IMO.

That is what I was saying. It is like a new service in that it has 3 wires. I thought I explained that when I said to bond the neutral to the can and drive some rods.

 

[tom baker]

Before 2008(?) NEC you could could run three wire feeder to a second structure and ground the neutral at the second structure. Exceptions since the change still allow for that in existing installations, but run a new feeder and you need to pull an EGC.

The 2002 NEC prohibited regrounding the neutral if there was a parallel path. The 2008 NEC prohibited regrounding the neutral, with exceptions for existing.

 

[kwired]

That is what I was saying. It is like a new service in that it has 3 wires. I thought I explained that when I said to bond the neutral to the can and drive some rods.

Sorry for the confusion. Perhaps one could say "treat the feed to the house like it were a service" and ground the neutral at the house. That is essentially what the general rule was before 2008 - then the 2002 rule came about as mentioned for parallel paths.