today i was experimenting with my megger. i was testing it using the 1000v scale. i cut the insulation across the entire cable with my razor knife so the black and white were knicked then i tested that and everything was ok. then i wet the cable with a little bit of water and tested between the black and bare. all of a sudden it started to spark where i cut it and melted a little bit and smelled of burning plastic. is this something i should worry about if i test a piece of cable (mc, old bx, old romex etc..) inside of a house. i dont want to start any fires or worry the people living there. should i test it at 500v instead because it didnt spark then?