Disconnect 3rd leg for G-GC Ground Check circuit?

[PlasticFarmer]

I am looking to do something unconventional and I cannot seem to find anything in the CEC for guidance. We have a 600V single phase machine that is used for underground mining work. In order to light up the feeder panels, a ground conductor monitoring (GCM) circuit must be closed at the load. It feeds a small current back up the ground of a Type G-GC feeder cable to verify its continuity to the feeder panel.

The simplest way that I can add this seems to be by running it through the unused 3rd leg of the disconnect, through a neutral link and the required zener diode and then into the ground. Throwing the disconnect would then tell the GCM module in the feeder panel to open/close the contactor. It seems fairly safe, as throwing the disconnect simultaneously kills the load and its feeder in series.

I have seen this done lots of times with an auxiliary contact added to a disconnect (thanks Square D) but the older equipment doesn't appear to accept one. Does anyone see a reason why using the empty third leg would not be acceptable? What part of the code if any would cover this?

 

[tortuga]

I am looking to do something unconventional and I cannot seem to find anything in the CEC for guidance. We have a 600V single phase machine that is used for underground mining work. In order to light up the feeder panels, a ground conductor monitoring (GCM) circuit must be closed at the load. It feeds a small current back up the ground of a Type G-GC feeder cable to verify its continuity to the feeder panel.

The simplest way that I can add this seems to be by running it through the unused 3rd leg of the disconnect, through a neutral link and the required zener diode and then into the ground. Throwing the disconnect would then tell the GCM module in the feeder panel to open/close the contactor. It seems fairly safe, as throwing the disconnect simultaneously kills the load and its feeder in series.

I have seen this done lots of times with an auxiliary contact added to a disconnect (thanks Square D) but the older equipment doesn't appear to accept one. Does anyone see a reason why using the empty third leg would not be acceptable? What part of the code if any would cover this?

I believe you are dealing with a Class 1 circuit, its probably okay but the wires need to have the same insulation rating as the 600V feeders. I believe its Section 16 of the CE code.

Rule 16-008 notes that Class 1 or Class 2 circuits installed in hazardous locations are also subject to the rules of Section 18.
Rule 16-010 specifies that remote control circuits to safety control devices where failure could cause a fire or a life hazard are to be considered and installed as Class 1 circuits.

 

[PlasticFarmer]

Thanks kindly, Tortuga. 600V wiring it is.
Cheers.