Agreed, 100mA is nothing through the key switch (although relay is always active with the key). Maybe I misunderstood Matt's arrangement; I didn't see the relay there..
Late night reading..
So the answer is yes.
You prefer to run additional loads directly from the unfused ignition switch.
As I said, I'm worried about the integrity of the white/blue wire.
Maybe yours is in better condition than mine :)
You prefer to run additional loads directly from the unfused ignition switch?
Maybe I misunderstand.
I'm worried about the integrity of the white/blue wire connections after 45 years, so I prefer to avoid loading it further where possible.
Sure, you can do it that way, but your 30A relay will be unprotected by a fuse unless you add one up stream. It will also be active continually whenever the ignition is on, regardless of whether your switches are on.
Alternatively you could feed the new fuse box directly from the battery...
Personally I'd tap a new waterproof fuse box directly into the battery connector to power things like extra lights, and just use the ACC to drive the relay coil.
This way you avoid putting even more load through the ignition switch.
The radio feed is a handy tap to drive just a few relays via...