[theshrike79]

When it's -25C outside the wires heating up isn't really an issue, it's more of a bonus feature :D

But yea, the cabling needs to be checked by an actual electrician and they'll determine how many cars can be charged in the ye olde block heater system without melting any wires or tripping fuses.

The 1980's stuff can usually handle 8A continuous loads. They changed the standard some time in the mid 90s, those can handle multiple cars at 10-16A continuous depending on the main fuse.

Anything above that and you'll need to overhaul the whole field and people usually go for Level 2 capable cabling if they need to break ground for cabling anyway.