Don, actually, installing a fuse in the common would provide better protection for the ancient PW Type Z/Zw transformer, as you can limit the current draw to 10 amps. Do note that all U terminals are connected internally, so you can use one as common for all circuits. Having said that, the terminals are riveted to a common internal buss, and over the decades these connections may have deteriorated.
I also recommend using breakers rather than fuses. The latter cost to much, as they'll blow on every derailment. In a recent thread GRJ has piinted to a source for magnetic breakers. I currentlyuse thermal breakers, which are slower and cheaper, but am considering whether to switch to the magnetics GRJ recommends..
