I do not know what the testing pocedure is in the States but here in the UK Insulation tests are required to be carried out at double the running voltage. So 240v systems are meggerd at 500v, and 415v at 1000v
As for digital / analouge meters I prefer to teach using analouge (but cant get new ones) just becouse they are easier to understand. But use a digital away from the school
