Grounding boxes and outlets on Isolated grounding outlet

[ks68jazz]

do you need a seperate grounding conductor for raceways and boxes containing isolated grounding outlets?

[iwire]

The IG needs to be separate from all raceways and boxes, so you will need another grounding conductor to ground the boxes.

However that conductor could be the raceway itself.

Look at it this way, do all your wiring as always and add a separate grounding conductor for the IG terminal on the outlet this Isolated grounding conductor should go all the way back to the bonding jumper for the system feeding the circuit.

This could be the at the main service or at the XO of a SDS transformer. (sorry Bennie) ;)

[bennie]

Bob: I agree completely with your statements. The isolated ground conductor should definitely connect at the X-O of a transformer that is a separately derived system.

The isolated ground should connect to the service, and building ground, when the transformer is an electrical extension of a multi-ground neutral system (MGN). :D

[Ed MacLaren]

I believe most codes prohibit carrying the insulated (isolated) equipment grounding conductor back farther than the system's grounding point. Ours (Canada) does.

This sketch might help illustrate what Bob and Bennie have stated.

http://www.electric-ed.com/images/IsolGnd.gif

Ed

[ August 03, 2003, 10:54 AM: Message edited by: Ed MacLaren ]

[websparky]

Nice drawing Ed!

[gwz2]

What is typical color coding when the isolated Ground Receptacle is in a nonmetallic ' Panduit ' raceway on the end of a metallic raceway system ?

[iwire]

We will use straight green for equipment grounds and green with a yellow stripe for the Isolated grounds, this is a stock item at our supply houses.

This also matches up with the color code in many manufactured items, modular office walls, computer room equipment, isolated ground MC cable, etc

[gwz2]

As usual ED, a great drawing.

I would suggest a note somewhere near the transformer with text similar to the following:

"If a "Service" transformer, then two (or more) points of grounding permitted on the grounded conductor to the Service Equipment. If a SDS then only one point of grounding permitted on the grounded conductor."

Just looked at a similar installation ( in progress ) which is a SDS.

By the way, I've lost the diagram on my replay of this subject. WHY ?

[brian john]

Hey ED what type of conduit would you utilize between the transformer and the main/panel?

[iwire]

When I look at Ed's drawing I see a service, which would mean overhead with aerial cable or underground with PVC. :)