Ground connection in remote panel (again)

[Ken Amelin]

OK, So this house has a remote panel located in a detached garage, Approx 50ft from house.
The panel is fed from main service equipment with three conductor cable. The panel ground and neutral conductors are connected to a common terminal strip and this panel has its own ground rod connection in the garage. Since this panel is grounded separately, should the neutral and ground still be isolated and would it require an additional grounding conductor connected to the main service equipment?

[Jerry Peck]

First, a question: when was the garage built/wired?

Years ago, detached buildings were allowed to be fed with three wire feeders (with the condition that there was no metallic path back to the main building - no metal water or gas piping, no phone or cable/antenna wire, no intercom wire, etc).

Also, years ago, the above was changed to require 4 wire feeders.

The service at the detached building was always required to have its own grounding electrode system.

[Ken Amelin]

First, a question: when was the garage built/wired?

Years ago, detached buildings were allowed to be fed with three wire feeders (with the condition that there was no metallic path back to the main building - no metal water or gas piping, no phone or cable/antenna wire, no intercom wire, etc).

Also, years ago, the above was changed to require 4 wire feeders.

The service at the detached building was always required to have its own grounding electrode system.

Thanks Jerry. The building was built in 1994. Should an additional ground wire be added?

[Jerry Peck]

Ken,

I'm not where my codes are and am having a 'brain fart' as to when the change took place. I'm thinking it was early/mid 2000s, but I'm not sure.

You got the grounds and neutrals together, I'm guessing.

[Jerry Peck]

The building was built in 1994. Should an additional ground wire be added?

"Should" is an interesting word. :)

The code allowed the 3-wire feeder up through the 2005 NEC (with the stipulations I mentioned earlier ... i.e., no metallic path from the detached structure back to the feeding structure). The 2008 NEC required a 4-wire feeder.

Notice that the 2008 NEC "required" a 4-wire feeder, while the 2005 "allowed", with conditions, a 3-wire feeder ... which brings us to the word "should" ...

"Should", as in: there is a raceway with a 3-wire feeder in it, and there looks to be plenty of space for a 4th wire, so ... yes, the 4th wire (equipment ground) "should" be installed.

However, "should", as in: "required" ... the 4th wire was not required by the NEC in 1994 (locally? maybe, but probably not required at that time either).