Electrical safe zone for vaulted ceiling

I'm renovating a property and vaulting a kitchen ceiling to gain more head height. The floor will be a slab which is yet to be laid.

Would it be better to run the cables for sockets down from the top of the wall where it meets the pitch of the ceiling or up from the floor slab (from within conduit within the slab) to be compliant with electrical safe zones? The consumer unit is in this room so either is easy in terms of access.

Just keeping in mind the 150mm you are allowed at the top of the wall but not sure if this is relevant if the ceiling is vaulted?

Based on nothing whatsoever, I would say that the zone is still valid.
There is often a triangular hollow space between the top of the wall and the ceiling timbers in this kind of construction, which I have used for the horizontal cable runs.

brianmoooore said:

Based on nothing whatsoever, I would say that the zone is still valid.
There is often a triangular hollow space between the top of the wall and the ceiling timbers in this kind of construction, which I have used for the horizontal cable runs.

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Unfortunately no such luck. I was going to run the cables along the wall plate covered with plastic capping. Plastering will be 3 coat Lime.

The usual way of finishing this would be to insulate and board the roof timbers, then board up the wall, usually over insulation, until it meets the roof boards. This leaves the triangular space on top of the original wall that I referred to.

brianmoooore said:

The usual way of finishing this would be to insulate and board the roof timbers, then board up the wall, usually over insulation, until it meets the roof boards. This leaves the triangular space on top of the original wall that I referred to.

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ah right. thanks that makes sense. Not sure what I am doing with the wall so far. It's a listed building so very much up to the conservation officer. Suspect it will be wood fibre insulation between and below rafters and 3 layer Lime plaster on the wall. Won't leave much of a triangle that way.

The lime plaster will be 25mm deep so thinking that cables in capping should be covered ok shouldn't it?

Don't get me started on English Heritage conservation officers! Did a job for a couple of them once. They wanted "to recreate a 18th Century Stanner's (tin worker) cottage for them to live in. My first comment was: "well, you won't be needing me to fit electrics and plumbing then", but it turned out they didn't want it quite that authentic.
They were a scammers dream. I told them that some of the floorboards I'd taken up were rotted beyond reuse, so told them to source some. They came up with a few planks that they had bought at great expense as genuine reclaimed oak floorboards. They were clearly an old oak barn door, rotted off at the bottom, that some local farmer had broken up - you could see the ledge and brace marks across them.
I got to see quite a few of their work files while I was there. They spent their days plotting how to make things difficult for anyone working on a property where the owner had been daft enough to let these jokers in at some time and let them list it.