I note that nowhere have you mentioned any payment being offered for electricity supplied to the neighbour. Your meter box and fuses or circuit breakers would have been designed for the supply to only one unit. If it has a power point then that is limited to 15 amps, if that circuit becomes overloaded the fuse will blow or the breaker will trip. Your neighbour will require much more power if they are to run any heating or cooking device. If circuit breakers or fuses are tampered with, then you run the risk of causing a fire with overloaded wiring. Additionally many extension leads are only suitable for indoor use, if used incorrectly they can cause electrocution hazard. I am staggered that a Strata manager would request that you supply electricity in this manner, given the hazards involved. Hope they have a substantial professional indemnity policy, they’re going to need it with advice like that.