Mains cables for powered roller blinds - bit naughty or ok?

[OscarLomax]

Hello all,

Having some cables routed to window reveals to allow powered roller blinds to be used in the future in a big open back room. Electrician is putting FCU close to each window but the route the spur then takes concerns me! The cable needs to appear in the top corner of the window recess, right where the end of the roller blind will be. To get there the cable basically pops around the corner into the reveal and then rises up the edge of the window (as in picture).

The room will be plastered very soon so checking this is ok. Sparky says as it's all in corners it's fine. And I appreciate that no one will hang a picture there so no nail banging likely. All circuits are on RCDs. However, just wanted opinions...


Thanks

 

[JohnW2]

That's quite an interesting one, and I'll be interested to hear what others have to say. Cables within 150mm of a corner (internal or external) of a wall, or within 150mm of the top of a wall (normally ceiling) are OK, but I'm not sure what the situation is when one is talking about window recesses!

Kind Regards, John

 

[Iggifer]

Window recesses do not apply, same as doorways do not count.

 

[EFLImpudence]

I agree with Iggifer.

It says the corner formed by two adjoining walls - not the edge of one.

 

[JohnW2]

I agree with Iggifer. It says the corner formed by two adjoining walls - not the edge of one.

Yes, I also agree that (assuming the window recess is more than 150mm deep) much of the route shown would be non-compliant. However, does not the room-side of the recess count as an 'external corner of the wall'? If it did, then moving the vertical run of the cable to within 150mm of that corner might be OK - but there still might be a problem with the horizontal bits.

Kind Regards, John

 

[Iggifer]

Nope, same as a doorway, even if the threshold is 150mm it's not a zone. Take the doorway example (same somewhat applies to a window) Someone puts a cable in the (non-existent) 150mm zone from the doorway (not including switch cables for any light switch that's there) 5 years down the line, a new owner bricks up this doorway for whatever reason - there is now a cable smack bang in the middle of the wall.

This cannot happen with internal corners, they're fixed, doorway and window positions are not (as much so as corners anyway). External corners can move, but there's more structural work involved there than bricking up a door/window so you're definitely going to expose the cables

 

[Echo the husky]

Go straight up from the switch, then drill at an angle to the corner of the window? Then fit a flex outlet where the cable comes out by the window, that will create a horizontal safe zone where the last bit of cable will be buried less than 50mm deep? An architrave grid plate with a flex outlet module would make a discrete outlet.

 

[EFLImpudence]

However, does not the room-side of the recess count as an 'external corner of the wall'?

It may be the edge of the wall but it is not a corner formed by two adjoining walls.

If it did, then moving the vertical run of the cable to within 150mm of that corner might be OK - but there still might be a problem with the horizontal bits.

That would be no more advantageous than straight up from the accessory and along within 150mm. of ceiling.
What you would then do in the recess, I don't know.

I see subsequent posts have solved the problem.

 

[JohnW2]

Nope, same as a doorway, even if the threshold is 150mm it's not a zone. ...

Is what we're looking at not rather different from a door frame or window frame? It's a block wall that goes a significant distance around the corner. How deep would the recess have to be before you called it a wall?

This cannot happen with internal corners, they're fixed, doorway and window positions are not ....

I may be wrong, but you seem to be talking as if external corners don't create zones, but 522.6.202(i) doesn't appear to say that. Indeed, it's not uncommon for people to be advised in this forum that an external corner does create a safe zone. In fact, I'd personally say that the part of a wall close to an external corner is probably 'safer' (from unthinking people with drills, hammers and nails!) than the corresponding place in relation to an internal corner.

We often discuss the extent to which is is necessary, required or sensible to take account of changes that theoretically may happen at some point in the future, and I wonder whether the bricking up of windows perhaps comes into the category where there is appreciable room for debate.

Kind Regards, John

 

[Iggifer]

I may be wrong, but you seem to be talking as if external corners don't create zones, but 522.6.202(i) doesn't appear to say that

That's why the second half of that paragraph goes on to say you could move an external corner, but in the process of tieing the new wall in, you'd likely expose 150mm of plaster (not sure why you would extend one in most cases though)

I don't think the picture shows any more thickness than a standard window/door opening. Granted the window isn't where a 'normal window' would be, it appears to be mounted on the other side of the cavity, but it just appears to be a standard external wall with block, cavity and then presumably brick (or block & render)

 

[EFLImpudence]

That's why the second half of that paragraph goes on to say ...

I'd like to find something to exclude external corners but cannot find what you say.

Could you explain, please.

 

[seasickstevie]

Granted the window isn't where a 'normal window' would be, it appears to be mounted on the other side of the cavity ...

Isn't the 'outer leaf' the normal place these days for a window frame? I thought it was.

 

[Iggifer]

I'd like to find something to exclude external corners but cannot find what you say.

Could you explain, please.

I'm not excluding external corners from safe zones, I'm just excluding them from standing much chance of moving

 

[OscarLomax]

Thanks for your input guys.

Window is pretty much sat on outer leaf, 70mm frame set ~40mm back from front of facing brick.

I like Echo's idea using a grid flex outlet. Spark is now saying why not put the FCU up near ceiling like you would a fan isolator. The wiring drops down from ceiling so sounds good to me, but now I'm worried about BCO complaining that I shouldn't have an FCU above recommended switch height(?). This is not something that'd be switched often so I am happy with it, waddaya reckon?

Cheers

 

[JohnW2]

The wiring drops down from ceiling so sounds good to me, but now I'm worried about BCO complaining that I shouldn't have an FCU above recommended switch height(?). This is not something that'd be switched often so I am happy with it, waddaya reckon?

I don't think that would be a problem. However, if you're saying that the power feed drops from above the ceiling, might it not be possible to bring the cable down through a hole drilled (or chased) through the block above the window, either >50mm below the surface or in a short length of earthed steel conduit, directly to some sort of outlet at the top of the recess?

Kind Regards, John