• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

isolated neutral

ICE

ICE

Oh Well
Joined
Jun 23, 2011
Messages
12,918
Location
California
There is a meter pedestal with a main disconnect about 200' away from a cell tower.This is a sub-panel at the cell tower.

View attachment 1941

This is an automatic transfer switch. There is also a manual transfer switch.View attachment 1943

Here's the deal. There are neutral/ground bus and lugs aplenty. So I asked that the equipment ground be removed at the main and checked that the neutral is isolated at the sub-panel. It is not isolated. As near as I can figure, the surge protectors in the ATS are where the neutral and ground are tied.The ATS is made by Kohler and is UL listed. My problem is that I don't know enough to decide if this is a problem or not.I wrote a correction regarding the non-isolated neutral and will find out more from our electrical engineer on Monday. I doubt that this has not been addressed by Kohler in the past and the contractor is heading their way.View attachment 1941

View attachment 1943

/monthly_2013_09/DSCN1918_zps64c8e5b8.jpg.d23138d41c4dc2f2edb8971101c66e17.jpg

/monthly_2013_09/DSCN1922_zps7331a341.jpg.3da1b10f2cd2db7a6c79f6a29d9a114f.jpg
 
Last edited by a moderator:
Don't forget to ask electrician to use common trip three pole breaker for common neutral circuit.
 
Span said:
Don't forget to ask electrician to use common trip three pole breaker for common neutral circuit.
Click to expand...
Doesn't have to be common trip just equipped with an identified handle tie.

Chris
 
Chris,

I didn't find that on the label and Kohler is no internet help because the model # isn't recognized. (KCS-DFNC-0200S)

The continuity between ground and neutral happened because a temporary receptacle outlet was bonded to an equipment enclosure. It's power came from an adjacent enclosure for another cell companies equipment. The service supplies both company's subpanels. The neutral for the new subpanel was disconnected at the main and a test showed an isolated neutral.

So the ATS must not be listed for use as service equipment.

285.23 (B) At the Service.

When installed at services, the grounding conductor of a Type 1 SPD shall be connected to one of the following:

(1) Grounded service conductor

(2) Grounding electrode conductor

(3) Grounding electrode for the service

(4) Equipment grounding terminal in the service equipment

I learned a few things this time around.
 
You must log in or register to reply here.
Top