The reason I was thinking about getting a new CU is that the house currently has an old-style fuse board.
Which probably means only a few circuits as well.
My son and his girlfriend have only just bought the place and are in test and tear-down mode at present. They have yet to move in.
There will never be a more convenient or cheaper opportunity to do a complete rewire, or add all the new circuits they might want, add all of the sockets and switches that they want, and so on.
The electrician will be able to make as much mess as he likes with chasing tools and SDS chisels without having to worry about soft furnishings, possessions and full-spec hoovering up each day. He won't have to worry about restoring power, moving furniture around, replacing floorboards etc. All of these things will shorten the job.
Your son and his g/f won't have to worry about mess and decorative damage, nor end up damaging their new hardwood/tiled floors, wallpaper etc in a year's time.
They should think hard about where to have sockets - it's difficult to have too many, and also about what circuits to have. The items on the list below won't all apply to them but they are worth thinking about:
- Upstairs sockets
- Downstairs sockets
- Kitchen sockets
- Circuit for appliances
- Cooker circuit
- Non-RCD circuit for F/F
- Non-RCD circuit for CH boiler
- Dedicated circuit for hifi
- Dedicated circuit for IT equipment
- Upstairs lights
- Downstairs lights
- 5A round pin sockets controlled by light switches for table/floor lamps
- Immersion heater
- Loft lights
- Shower
- Bathroom circuit
- Alarms
- Supply for outside lights
- Supply for garden electrics
- Supply for shed/garage
Plus any peculiarities brought about by the house layout & construction - e.g. in mine because of solid floors and where the socket circuits run, I have a radial just for a socket in the hall, the doorbell and the porch lights.
I like the idea of putting all wiring in conduit for ease of future changes. And if they specify metal conduit for switch drops, or BS 8436 cable it removes the need to have RCDs where they'd rather not.
Unless they want to go to the expense of RCBOs throughout, the CU should have at least 3 sections, 2 on RCDs and one not into which they can install a mix of RCBOs and MCBs.
If they live somewhere where supplies are dodgy in the winter, have the lights, the boiler supply, and a socket in each room wired to a separate CU, or a separate section in a large one, that can be supplied by an emergency generator - lights, heating, TV and a kettle/microwave make life a lot more bearable.
Flood-wiring with
Cat6 or Cat6a cable is worth thinking about.