SunNinja
Member
- Location
- Washington
- Occupation
- Electrician
I'm trying to figure out whether it is safe & appropriate to megger - or insulation resistance test- positive to negative on a single string connected to PV modules. I do troubleshooting exclusively with a new job, a lot of arc fault and ground fault problems. I recently used a Seaward meter at a commercial site for IRT tests with modules that are in the sun, producing voltage. We disconnect all positive wires at the fuses in combiners, and run the test between each + string leg and the negative bus, and I was assuming to ground from + strings as well.
I have a Fluke DMM with IRT capability, and I went to do a test between + and - at a single string disconnected from the inverter, but there was a little sparking going on when I went to connect the meter lead to the + side string. Double/ triple checked all connections for polarity and plugging into the appropriate spot on the DMM for IRT.
Made me second guess whether this is something that is commonly done, or whether a Seaward meter has some fancier internal protections or??
The company has some conflicting guidance that gets painfully specific and elementary about how to test BUT never says test + to - on a string, or + to ground. But there's one line that says if panels are in the circuit, IR must be above a certain amount.
Any experience/ information appreciated.
I have a Fluke DMM with IRT capability, and I went to do a test between + and - at a single string disconnected from the inverter, but there was a little sparking going on when I went to connect the meter lead to the + side string. Double/ triple checked all connections for polarity and plugging into the appropriate spot on the DMM for IRT.
Made me second guess whether this is something that is commonly done, or whether a Seaward meter has some fancier internal protections or??
The company has some conflicting guidance that gets painfully specific and elementary about how to test BUT never says test + to - on a string, or + to ground. But there's one line that says if panels are in the circuit, IR must be above a certain amount.
Any experience/ information appreciated.