Adding internal fuses to Ferranti 255 - A Good idea?

[Nick]

Should you fuse both leads to the mains transformer primary? If the one in the neutral lead blows it still leaves the transformer live.

Doesn't guarantee anything - typically, only 1 will blow, and its 50/50 if it'll be the live or neutral, however I'd always assume 100% that it was the neutral and the set would still be live

A two pole breaker would do the tick - if either or both trip, the circuit is isolated...