You are looking for an exclusive use by law.
The owner of the affected lot has to agree to the bylaw.
I am thinking that you want this bylaws(s) to apply to each unit .
If one owner objects to his bylaw, and everyone agrees to theirs, then the OC is still responsible to fix the wiring.
I am guessing some owners can’t pay their share of the electrical upgrade. Remember the OC is responsible to maintain and repair common property. Since electricity is a basic service the OC provides to owners, if the owners don’t do something immediately, it’s going to be an easy decision for NCAT to issue an order.
Perhaps consider a strata loan to fund the work.