Firstly you have to find a connector that is rated for the
DC voltage you need, *in a domestic environment* Some broadcast
and studio connectors, are rated at 1500V industrial but only 70V
domestic.
For your private use, you have a greater freedom of choice, and are
only dependent upon what an insurance company will accept. But if
you plan to sell to the general public then the situation is different.


Bill Beard used 8 pin Speakons for umbilicals. These are presumably
rated 250v for domestic as well as industrial. That's going back a few
years. Neutrik has downgraded all its 250v rating for XLRs to 50v in
latest literature - presumably this is domestic? Same plugs of course -
data sheet still says 250v and their salesman confirms it. I'd be
looking at up to 350v, so may be on dodgy ground here. No free lunches.
I'm OK with the filaments in the D connectors, but still need to look
at the B+ situation. Length of lead is interesting - never thought of
that. Loads of new regs coming in it seems.