When I fitted my socket, apart from also fitting an in-line fuse, I connected the accessory socket via the main switch (on the heelboard on the '93 car, under the dash on the '76). This ensured the socket wasn't live if I removed the big red key.
I also put in a fused feed direct to the battery with a C-Tek battery charger connector.
In both cases, the leads (wires) are protected with flexible conduit as both connectors are free (floating) down by the passenger seat...
