scuwp: The OP is doing 'electrical' work in a house and doesn't know what a master splitter is?
Please stop now and call a qualified tradesman.
No, this is actually easily close to the norm. Electricians have always traditionally been the trade to install TV aerials on new builds and also to connect and run the phone cabling. It is still very common to find dedicated phone lines daisy chained throughout a new house to dedicated phone only outlets, of which the broadband modem is plugged into one of them.
The advice to call someone qualified is right, but most home-owners don't realise the need for data and TV aerials to receive more specific attention, let alone many tradespeople. Phone lines should have master splitters installed and TV aerials should no longer be multiband 'Gizmo' styled aerials just because the local wholesaler says "this is what everyone else is installing"...