permitted routes - sloping ceiling

[opentoideas]

could anyone confirm the wording of 522.6.6 (v)?

i have not updated from my red book 17th  and have a conflict i am trying to resolve between it and the A3 OSG 

i have to run a cable in a permitted route at the top of a wall which meets a sloping ceiling.

BS7671 522.6.6 (v) reads "(v) be installed in a zone within 150 mm from the top of the wall or partition or within 150 mm of an angle formed by two adjoining walls or partitions."

therefor my route would comply with 150mm from the top of the wall and the slope is not relevant.

my A3 OSG however defines this in 7.3.2 (b) as "be installed in a zone either horizontally within 150mm of the top of the wall"

this would not give me a permitted route so i would have to comply in a different way.

first off its time i stopped being tight and bought the yellow book but can anyone tell me if the wording has been changed? 

thanks 

 

[Andy™]

OSG is just a guide, follow whats in 7671 (you'd think they would be the same though)

 

[opentoideas]

thanks,the problem is my 7671 is out of date and i wanted to check before i get the new one tomorrow that they have not changed the wording.

while i keep my OSG up to date i have been lax in updating the full regs but its ordered now.

i suspect that the OSG is just going for an easier to understand description but i also wouldn't be surprised if the wording of 7671 has been changed in the amendments.

the addition of one word makes a difference and with the drive to make all runs horizontal or vertical i cant be sure of this until i get the up to date 7671.

 

[ProDave]

If YOU believe the sloping bit to be a ceiling, treat it as a ceiling. If YOU believe it to be a sloping wall, treat it as a wall.  All a bit open to interpretation.

But whether it's a wall or a ceiling, you are going to fit something to it. So keep the cable horizontally or vertically from the accessory, and it doesn't matter if it's a wall or a ceiling, it will be in a safe zone.

The bit describing where two walls or partitions join at an angle, is really meant to describe the corner of a room, which this is not. However if you believe your sloping bit is a ceiling then you have the safe zone at the top of a wall.
 

 

[Murdoch]

I would venture to suggest that a wall is vertical, and the ceiling isn't - and work from there.

 

[opentoideas]

i agree fully that the responsibility is mine and you should note that i have not asked for anyone to "justify" my belief for me.

the part i am fitting to is not sloping it is a vertical wall the top however meets a sloping ceiling. the problem is that to remain within 150mm from the ceiling would result in the cable path NOT being horizontal.

while this is certainly not my preference, thats the job site i have to work with and if the wording in 7671 remains the same then i believe it will be acceptable. 

i will have the answer for sure when i get my updated 7671 but i was curious to see if there was a discrepancy between the wording of 7671 and the OSG as the wording makes a clear difference in this case.

Murdoch - you are quite correct the problem is  as you have understood with the sloping ceiling meaning there is no horizontal permitted route available to me

 

[ProDave]

So to try and fully understand the situation, you are fitting something to a WALL that adjoins a sloping ceiling a bit like you would find in a dormer window situation where the ceiling is sloping. You want to run the cable in the 150mm zone at the "top" of the wall, but because of the slope of the ceiling, that zone also slopes at the angle of the sloping ceiling.

This is certainly one of those open to interpretation situations, as all the pretty pictures that explain the zones don't seem to include sloping ceilings.  But it seems to me it does meet the description and the letter of the regs. Whether it meets the intent of the regs we could debate until the next edition comes out.

But is there any way instead you could run the cable up above the sloping ceiling bit instead of along the top of the wall? that would seem to be more certain. As long as that IS a "ceiling"
 

 

[Murdoch]

I would say that if the cable runs In the 150mm zone from the ceiling it's ok. This would include a cable running at an angle

A sketch would be useful

 

[opentoideas]

Yes it's a ceiling but it's also a modern roof with 200mm of insulation and far more of a problem than a wall chase.

I don't want to debate the merits of methods as any spark must make these determinations with the unique site conditions in mind and each situation is different. Certainly it's not my first choice cable route but we always have to be able to work out the most appropriate use of the regs given the specific site conditions. 

I would say that if the cable runs In the 150mm zone from the ceiling it's ok. This would include a cable running at an angle

This is certainly one of those open to interpretation situations, as all the pretty pictures that explain the zones don't seem to include sloping ceilings.  But it seems to me it does meet the description and the letter of the regs. Whether it meets the intent of the regs we could debate until the next edition comes out.

Yeah this is the reason I asked. Whilst I may not like it the letter of the regs is what it's all about and in this specific case all other options are equally as bad. The ceiling is modern so board over 100m insulation and 150mm insulation between joists and a 50mm gap to felt so I really don't want to mess with it and a wall chase in these circumstances is a non issue they are already creating a large wall chase for plumbing so no need to destroy the ceiling as well.

As you say it is not in the spirit but it's all about the wording and it's the only sensible option but without checking the ammendment I am not prepared to sign off on it.

Just hoped someone had it to hand to check the wording was the same as my older one

 

[ProDave]

...... The ceiling is modern so board over 100m insulation and 150mm insulation between joists and a 50mm gap to felt so I really don't want to mess with it and a wall chase in these circumstances is a non issue they are already creating a large wall chase for plumbing so no need to destroy the ceiling as well.

Things like this dismay me.  It's good that builders are finally fitting a decent amount of insulation, but they need to learn that in such situations, the correct and modern practice is to leave a battened service void at least 25mm wide between the bottom layer of insulation, and the ceiling plasterboard. Had they done that, you would have an easy cable route above the plasterboard of the ceiling.

 Perhaps you should mention this to the builder, in a constructive manner, and they might actually start making buildings that are easy to install the services into.

 

 

[Sidewinder]

@opentoideas IMHO I would go with the zone at the top of a wall adjoining a ceiling, even if that ceiling is sloping is a safe zone.

I have put a few excerpts from Amd1 & Amd3 & Amd3 GN1 in the attached pdf.

In case you have not made the decision yet.

BS7671 Amd3

522.6.6 is no longer a reg number.

I don’t have a copy of the red book to hand, only green & yellow electronically, red book is in the library.

View attachment Safe Zones.pdf

 

[Sharpend]

Concur