DC system ground fault protection

[jcc146]

I am installing an owner furnished solar water pump 'kit' consisting of four 12volt PV panels. it is stand-alone, no batteries, no interconnect. it will drive a 48 volt DC pump. a disconnect is provided with a controller specifically to operate this paticular pump.

the question is, am i required to install DC ground fault protection on this?

there is no AHJ in my area, so i cannot ask him/her..........

 

[beanland]

DC Ground Fault Detection

DC Ground Fault Detection

I am not sure anyone makes UL-listed DC ground fault protection. In the DC systems I am familiar with, we completly isolate the DC from ground. We then use idiot lights or a meter to detect a ground condition. Basically, two lights, each from a DC terminal to ground. If either side of the DC goes to ground, the other light turns on. As long as only one side of the DC is grounded, there is no fault. This is the same concept that is used in ungrounded electric services.

 

[Besoeker]

I am not sure anyone makes UL-listed DC ground fault protection. In the DC systems I am familiar with, we completly isolate the DC from ground. We then use idiot lights or a meter to detect a ground condition. Basically, two lights, each from a DC terminal to ground. If either side of the DC goes to ground, the other light turns on. As long as only one side of the DC is grounded, there is no fault.

We have used a similar concept where we have DC distribution on drive systems. Typically these are 600 - 800Vdc.
Two equal resistors are connected in series across the DC and the center point taken to ground. There is a voltage sensing relay across each resistor. The trip point of the relays is set so that they pick up if the voltage sensed significantly exceeds half the DC supply voltage. The relays can then be used send a signal for remote indication and/or to operate upstream protection circuits.