UTS6H Grounding

[Anonymous user]

After six months, I finally installed my UTS6H. Because my main electric panel is recessed between studs, I installed the UTS6H in the wall. The most difficult issue was drilling through a stud to run the wires. To do this, I had to remove the conduit and just run the wires through the stud. Because the wires are in the wall, I did not see this as a problem.

I purchased a UPS to use as the second back-up source. Plugged it in to the convenience outlet on the UTS6H and everything was working fine. The other day I noticed the Building Wiring Fault light was illuminated on the back of the UPS. After exchanging several emails with APC support, no viable solution was identified. I used my outlet tester and it indicated an open ground on the convenience outlet. I removed the cover from the UTS6H and could see the outlet, UPS inlet, and generator inlet were all grounded to the UTS chassis. Also, the circuit board had two ground wires going to the chassis. 

I found this forum and read all topics related to universal transfer switches. I did find one other forum member had the same issue. However, an answer to the grounding issue was not posted. So, I searched the Internet for issues related to grounding and any UTS. I could not find anything about installing the UTS. However, I did find several videos showing the installation of manual transfer switches. In all of them, the transfer switch had a grounding wire from the transfer switch to the main electric panel. 

In the site preparation guide, this statement is listed under safety precautions, "This unit must be connected to a properly grounded utility power source." Now to my question. How is the UTS6H grounded to utility power? Nothing in the installation guide discusses how to ground the UTS to the main electric panel. I'm thinking of running a ground wire from the UTS6H to the main electric panel bus bar. Would this create any other problems? I'm hoping someone on this forum had the same issue and find a resolution. 

I appreciate anyone's response.

Thomas

[BillP]

Hi Thomas,

I asked our resident UTS expert here. He said:

The panel is grounded to the Main Electrical panel through chassis ground. By removing the metal conduit between the two panels, you have effectively removed the ground reference back to the Main Panel. You have to either reapply the conduit or secure a ground wire between the UTS Chassis and the ground connection found within the Main Electrical panel.

I hope that helps clarify. Let me know if you have further questions.

[Anonymous user]

Hi Angela,

After looking at the panel with the cover off, I asked myself if the conduit was the ground. My suspicion was correct. My installation manual is dated 2008 and I did not see any reference to a ground wire in the installation guide. I suggest adding a statement in the updated guide that the conduit is the ground. 

Because I installed the UTS in the wall and had to drill a hole in a stud to run the wires, the conduit would not fit properly afterwards. It will be much easier to install a ground wire between the chassis and main panel.  I appreciate your assistance.

Thomas

[Anonymous user]

Good Morning Angela,

I ran the ground wire from the UTS chassis to the main panel. This did correct the grounding problem and issue with the building wire fault on the UPS. Now, I await the first power outage to use the UTS6H.

Thanks,

Thomas

[BillP · Accepted solution]

You're very welcome! I will be submitting a feedback on the UTS guide in relation to what you suggested.