In 30 years I don't think I've ever seen the secondary blow on a transformer except for a fuse on the secondary side. I have no idea why but it seems like its always the primary winding of the transformer that burns out. A short on the secondary side will burn out the primary windings if there is no fuse in the circuit. That being said if you have a bad neutral it can carry the other leg of the 220 & can burn out anything that is hooked up on 120v. I've seen people burn out things like vacuum cleaners & other appliances when the neutral lost its connection to the main putting 220v. to all the receptacles in the house.