I was thinking the same as Bob (iwire), in using a typical dry type power Transformer.

Then you could get sizes of 100 VA, 250 VA, 500 VA and 1,000 VA with Secondary Voltages of 12 VAC, 24 VAC or both!

Definitely need to size conductors per load, and fuse the primary side.
Secondary side could be fused per feeder, or total VA size - but better method would be per feeder.

Scott35

p.s. sorry to post minimal info! reply if more is needed!

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!