> Isn't the insulation on MOTs the same insulation on the secondaries of > NST's? I it'll last on 15 KV, why not 8? Nope... the NST is potted, the MOT isn't. It isn't the winding to winding insulation you are worried about here, it is the winding to core breakdown. Plunging the MOT in a bucket of oil would probably solve the insulation problem.