Electricity - passing through to another house

[damien]

Hoping someone maybe able to offer some thoughts on this.

My house is under a strata with one other house. Both houses are free standing and completely detached (no common walls). However the house behind me receives their electricity supply through my house. As in the power comes off the lines with 3 phases, 2 phases are used by my house and the 3rd phase has a separate switch in my meter box, clearly marked as rear house.

It is only a switch in my box (no meter) and I have tested it so when I switch it off the house behind loses all power. From my meter box the power runs down into the ground and stays underground pass our common fence and into the rear houses own meter box.

Is this normal for two houses that previously was only 1 big block before sub-division.

I am concerned that if I wanted to make any changes to m power box then it could effect the neighbours, does anyone know the ramifications of this?

And lastly should there be any details on plans or with Sydney electricity as to where the cable is as I would not want to be digging in my yard and I strike a power cable. Is there any way I can get the power removed from my meter box and forced underground before my meter box?

I should also mention that as we are a two dwelling strata with no actual common property I am currently in the processing of passing a by-law that will separate the two houses maintenance/insurance responsibilities, I am not sure if this would effect the electricity service

Thanks.