It sounds like in this situation the best solution is one of those suggested by Sir H, and that’s a user-pays system of either separate power supplies or metered electrical connections.
Another way round this would be to clear out all the individually owned washing machines and dryers and replace them with cashless user-pays communal machines (click to see one comercial solution).
This is the problem when what was once a communal facility is gradually taken over by some individuals while being abandoned by others.
There will be resistance to change. Those who are effectively being subsidised by other owners won’t want to lose that benefit. Those who are self-sufficient with their laundry equipment inside their flats won’t want to pay more towards communal facilities.
Possibly the best thing you can do is to circulate a plan to all owners explaining what you want to do and why and what the options (and costs) are, including the added cost to laundry non-users of keeping things as they are.
At the very least, a separate meter for the laundry and agreement for those given access to the equipment that they will share the costs would be fair.
But having half a dozen separate dryers leaching off communal electricity makes no sense. A couple of shared Hills hoists would be a step “back to the future”.