Freaking NIGHTMARE they are.
You have to troubleshoot TWO systems and every 50's system I've seen (in AZ) has the relays in the ATTIC!!...and it is always a total rat's nest!!!
Sometimes the relays are DC.
You can't simply add a dimmer.
You have to hunt for parts.
I have seen a few CURRENT systems. I can't believe that someone would think this is a good idea. Just because you CAN do something doesn't mean you SHOULD.
I have torn out a few of these systems and replaced them with standard wiring.
