My sister has an ancient ( circa 1962 ) Touchplate system.
Such low voltage systems cut down on wiring -- especially such items as 3 ways and 4 ways.
You can easily control the circuits via the relays.
Only downside is that they can stick in a latched single to relay condition. When that happens, as Greg said, you've got coil issues.
For whatever reason, it has not occurred to Touchplate and its imitator GE to resolve sticking plates with a C/B or fuse.
Why? I can't say. A fuse would have to be cheaper than ruining the coil.
IF that were done...
This type of lighting control would be all the rage -- years before electronics.
My sister's house is 48 years old -- and still has the original switches!
How many homes have their light switches unchanged after 50 years?
