Height of Power Outlets and dual ccts ?

Actually Q1 is 400mm. Q2 I am sure someone more knowledgeable will be along in a moment to cite chapter and verse.

Q1 is no Q2 not sure about

Depends.

It mustn't be so close to the floor that the plug/socket could get damaged (installation must be suitable for its location).

If it's a new build then Part M of the Building Regs (disabled accessibility) apply.

Permitted. It would be prudent to put a note in the back box, or label the cables, indicating this.

Owain

It is more important to ensure in such circumstances the neutral is tied into the appropriate circuit. My landing light (installed bt a nic/eic registered company) had it's neutral from the upstairs lighting, and the live from downstairs. This came to light after I installed a light (several flourescents fed from the landing light) in the loft. I pulled the fuse on the upstairs lighting circuit in order to move a ceiling rose. When I disconnected the neutrals, fizz bang, and darkness in the loft, accompanied by brown trousers.

Yes an no!

For an existing building you can place them anywhere you want so long as you end up making the building no less accessible to disabled people than it currently is. For new builds one ought to comply with part M of the building regulations (section 8), and this stipulates a minimum height of 450mm from the finished floor level, and a maximum height of

(also covered in fig 8A of the OSG)

It is permissible, and usually unavoidable in these situations. I typically wire both hall and landing with two way switches so you can switch either at either location.

I hope so:- I have one hall light circuit switched from 5 positions and the switch positioning means they are 'shared' with three lighting circuits. One benefit being that if any circuit trips there will be enough light spill to get down the stairs etc not in total darkness. This to me is far more important safety wise than any safety issue when doing maintenance etc. You can always leave a note inside the box if it worries you.

Yes 450mm.

No. Put any two way s*it on the same circuit.

While this solution has its attractions, there is no regulatory requirement for doing this, and it may be impossible in larger properties anyway.

Not a good idea for hall/stairway. If a circuit trips you loose all the light. If you split it to upstairs downstairs there will probably be enough for an emergency. Oh - you should *never* assume a circuit is dead because you've switched off what you think is the appropriate MCB. House main switch probably - but then it wouldn't matter if there are two circuits in one switch plate.