Trumpy, using the megger is not the problem.
Trying to find the acceptable test levels is. Also finding acceptable test proceedures. Sure using the little megger from Grainer is probably just great. I'm sure that in reality it works just fine. But you meg a house after some water damage and later something goes wrong. You find yourself in court. They will want to know the calibration date on the megger. They will want to know the proceedure and how it was documented, are you trained & certified ( sure I was certified 30 years ago in the military, but that was to meg cables in the nuclear field not Romex). I have asked 6 different engineers and got 6 different answers, I checked with the cable manufactures and they are not much help. It seems you need a team of highly trained engineers to keep from voiding the warrenty on the cable. Now if you want to meg industrial cables that is a whole different ball game because there are agreed upon tolerances ( set limits ). That's why most people just replace the cable after water damage or flood. That way you are sure that it want come back on you. We are a litigation crazed society and no one wishes to make a definative statement for fear of being sued. I can meg cables all day long and tell you if they are good for all practical purposes but I not so sure I can out wit a high priced lawyer. The reason I think the hipot test might be a good one is that it is accepted for the mobile home industry, and thus a precedent. If you have a documented proceedure that you are sure will stand up in an Amercian court ( remember that if the coffee is a couple of degrees to hot someone gets a million bucks if they are dumb enough to spill it on themselves) then by all means, post it.