I use this stuff AFTER I've put on a wire nut or similar to provide sealing to the connection from water/dirt/humidity. In particular, trailer tail lights. I hook the light connections with wire nuts, and then seal them with this stuff, and later on when the tail light gets hit/smashed/broken, it is far easier to replace and the wires are still good when it's removed. That's all 12v DC applications though.

I've never used this stuff on anything 120v or higher.

I see those are Chinese characters on the canister, and I'm guessing that's in China, where they use 230v 1 phase power, 1 hot, 1 neutral, 1 ground. I know, I lived there! Shady wiring was pretty typical.