I posted this on Mike Holt's forum earlier today:
A typical CT is available as 400:5 (equal to 80:1), meaning that one amp will flow through the meter for each 80 amps in the line (for a given phase, of course).
I've never opened one, but I take it that the CT has 80 turns of wire. Therefore, with an open secondary, the CT would operate as a 1:80 step-up transformer.
With even a lowly 120v primary, that would be (80*120) 9.6kv! That's higher than the average insulation rating, to say the least, as well as quite lethal.
