Protected zones - do they apply externally?

[0ldskoolskater]

Hi All,

Need to run some lighting cable in a yard for wall lights. Do the internal protected zones apply to external cable routes also?

The cable will be getting rendered over, so mechanical protection-wise will chasing a channel and metal capping suffice, or is there a preferred alternative?

The circuit will be electrically protected by RCD etc.

thanks

 

[oldbutnotdead]

There is no good reason that i can see not to follow permitted zones for concealed cables in an outside wall.
If you are rendering the wall deep enough you can clip the cables on the surface. Capping is also optional - talk to whoever is doing the rendering, see which they prefer.

 

[EFLImpudence]

Metal capping is not considered mechanical protection.

Mechanical protection would be 3mm. thick plate or conduit. I am not saying that is required; just what it is.

 

[0ldskoolskater]

Thanks both.
I'll likely chase a channel (depending upon the render thickness) within the usual protected zones.

 

[JohnW2]

There is no good reason that i can see not to follow permitted zones for concealed cables in an outside wall.

Not only "no good reason" but, unless I've missed it, I don't think there is anything which BS7671 says about such things that excludes 'outside walls', is there?

Kind Regards, John

 

[chivers67]

Would you consider using Metal Conduit to run the cable in?

 

[oldbutnotdead]

Not only "no good reason" but, unless I've missed it, I don't think there is anything which BS7671 says about such things that excludes 'outside walls', is there?

Kind Regards, John

Nope, but the zone 'within 150 mm of the ceiling' implies the focus was on internal walls.

 

[0ldskoolskater]

Would you consider using Metal Conduit to run the cable in?

Only if I could get the conduit sunk deeply enough into the wall such that it could then be renedered over, surface mount is not an option in this scenario

 

[0ldskoolskater]

Nope, but the zone 'within 150 mm of the ceiling' implies the focus was on internal walls.

The wall will have coping stones on the top so I'm going use that as the 150mm datum in this instance

 

[JohnW2]

Nope, but the zone 'within 150 mm of the ceiling' implies the focus was on internal walls.

Sure, and that 'focus' makes sense, given that interest will be on 'indoors' in the great majority of cases - but such a focus does not imply that external faces of walls are 'exempt'.

In practice, there's really only going to be a potential issue if the wall is rendered (c.f. 'plastered over'), and that the render is 'made good' very well, since the routing of a buried cable would otherwise be obvious. However, if a buried cable were properly 'concealed' by render, then I see no reason why there would not be the same concern about that as there would indoors.

Since you have mentioned it ( ), I wonder if the 'roof'; of say, a porch or carport would qualify as a 'ceiling' in this context?!

Kind regards, John

 

[0ldskoolskater]

Sure, and that 'focus' makes sense, given that interest will be on 'indoors' in the great majority of cases - but such a focus does not imply that external faces of walls are 'exempt'.

In practice, there's really only going to be a potential issue if the wall is rendered (c.f. 'plastered over'), and that the render is 'made good' very well, since the routing of a buried cable would otherwise be obvious. However, if a buried cable were properly 'concealed' by render, then I see no reason why there would not be the same concern about that as there would indoors.

Since you have mentioned it ( ), I wonder if the 'roof'; of say, a porch or carport would qualify as a 'ceiling' in this context?!

Kind regards, John

Healthy conversation - I like it!

The wall isn't rendered yet so this is technically 1st fix work. I've yet to ask the guy how thick the render will be though I am assuming I'll be chasing a channel to get it deep. On the topic of cable suitabability, I'm thinking arctic flex..