Cables and cavity walls

[diyterry]

If I want to run a cable up a cavity wall is it best to run it through the cavity or chase the wall out and run it through a conduit.

 

[westward10]

How can you chase a cavity wall.

 

[telectrix]

How can you chase a cavity wall.

all depends on whether the cavity wall is a fit young female cavity in a miniskirt.

 

[Spoon]

If I want to run a cable up a cavity wall is it best to run it through the cavity or chase the wall out and run it through a conduit.

What distance are we talking?
Does the cavity have insulation in it?

 

[westward10]

I understand now, brick wall with cavity.

 

[Octopus]

Cables on external cavity walls are complete no no imho

 

[Midwest]

Cables on external cavity walls are complete no no imho

With some limited exceptions.

 

[Pete999]

Don't give electrical step by step guides to DIYers

 

[diyterry]

What distance are we talking?
Does the cavity have insulation in it?

About 2m, no insulation in the cavity.

 

[Michael Sands]

Think you are only allowed 3m unsupported in a cavity or vertical duct but it all depends on insulation type for example styrene would degrade cable so probably best to chase so limiting damage when pulling in etc I could go on forever but whoever does job would decide on the job what’s best taking all factors into consideration this would take into account damage to decor and how expensive it would be to put right

 

[diyterry]

Cables on external cavity walls are complete no no imho

Can I ask why?

 

[Octopus]

Can I ask why?

Not supported, bridging the gap ..........

 

[diyterry]

T

Not supported, bridging the gap ..........

Thanks

 

[telectrix]

Not supported, bridging the gap ..........

so what about cavity wall ties???

 

[Toneyz]

so what about cavity wall ties???

They are designed so the water drips down the cavity and doesn't bridge Tel.

 

[Deleted member 26818]

There’s no prohibition in BS7671 against running cables in cavities.
In fact BS8436 cable is designed for use in building voids and BS7671 lists installation methods 40 to 44 as being writhing building voids.

 

[Midwest]

There’s no prohibition in BS7671 against running cables in cavities.
In fact BS8436 cable is designed for use in building voids and BS7671 lists installation methods 40 to 44 as being writhing building voids.

Can imagine anything (other than SWD) wanting to be in a writhing building void.

Would this be the sequel to cables in cavity walls thread part 5, discussion.

 

[Deleted member 26818]

Think that was meant to be within?

 

[Spoon]

I was thinking about @Michael Sands post above, about max cable length, so I went searching.

BBB - page 308. 721.522.8.1.3 states max length of 0.4 m between cable supports.
I can't find anything else in the BBB relating to the max length of cable between supports.

OSG - page 139 (g) states max length of 5 m between cable supports.

 

[Deleted member 26818]

Does the OSG reference a Regulation?

 

[Spoon]

Does the OSG reference a Regulation?

It only has 522.8 at the top of the page, mate.
No actual max length stated in 522.8.

 

[Midwest]

Think that was meant to be within?

You made a mistake and got something wrong!

 

[Deleted member 26818]

You made a mistake and got something wrong!

Nope, it was autocorrect.

 

[Deleted member 26818]

There are different rules for caravans, because they’re transportable, though the 400mm figure is for accessible cables.
It’s also unlikely that you would have a caravan where you could have a vertical run of 5m.

 

[Spoon]

There are different rules for caravans, because they’re transportable, though the 400mm figure is for accessible cables.
It’s also unlikely that you would have a caravan where you could have a vertical run of 5m.

Yeah mate. I just put the 721.522.8.1.3 reg down as that was the only reg I could find that actually stipulated a length.

Recently got the BBB and OSG. Ripped them to bits and scanned/OCR both of them... Makes them a lot easier to search.

 

[Deleted member 26818]

Does the program read all the words correctly?

 

[Spoon]

Does the program read all the words correctly?

Use Nitro Pro 10. Haven't had much of a problem with it up to now.

 

[Deleted member 26818]

Use Nitro Pro 10. Haven't had much of a problem with it up to now.

Can you use it on PDFs you already have, or must you scan the document using the program?

 

[Spoon]

Can you use it on PDFs you already have, or must you scan the document using the program?

You can use it on PDF's you already have.
I think you have to pay for it, as there is a licence...

If you need anything doing then, seeing that it's you, you could email it to me and I will OCR it. Then you can see what you think of it before hand.

 

[Deleted member 26818]

I have Adobe Acrobat.
Just seems a bit clunky.

 

[Spoon]

Nitro Pro 10 is just what we have at work so I use it. Seems good.

 

[Midwest]

Nope, it was autocorrect.

Pheeww, thank God for that.

 

[Spoon]

I have Adobe Acrobat.
Just seems a bit clunky.

If you are having problems with a PDF then I can OCR it with Nitro, if you want. See if its better..

 

[driverman]

Cables in external cavity walls are not allowed. Another reason why not, is that a 3rd party might hit them when drilling through wall to install TV cables etc

 

[westward10]

And they wouldn't hit them if they were chased instead?

 

[Spoon]

Cables in external cavity walls are not allowed. Another reason why not, is that a 3rd party might hit them when drilling through wall to install TV cables etc

Can you give a reg number for that mate?
Would someone drill through the full width of a brick (102mm) to fix a TV cable?

 

[Midwest]

I doubt if you could find a BS7671 reg or Building Reg against it. But if its at all possible, a cavity is not the place for any cable, unless its straight through or less than a couple of meters, aka meter tails etc.

 

[ukiri]

And they wouldn't hit them if they were chased instead?

That's what zones of protection are for

 

[Deleted member 26818]

That's what zones of protection are for

Prescribed routes.
You don’t think there would be a prescribed route if the cable were in the cavity?
You should also consider what happens to loose cables when drilled as opposed to captive cables.

 

[Midwest]

Thats that then. New builds should have all the cables run in the cavity, wouldn't have to worry about sheathing or clipping the cables.

 

[Deleted member 26818]

Thats that then. New builds should have all the cables run in the cavity, wouldn't have to worry about sheathing or clipping the cables.

Ahh, Irony, nice.
Just a little more subtle than sarcasm.

 

[Midwest]

Someone's tired.

 

[Deleted member 26818]

 

[pirate]

Irony?
Hmm...don't think I'll be phoning Alanis any time soon...

 

[Deleted member 26818]

Irony?
Hmm...don't think I'll be phoning Alanis any time soon...

I think the irony is that none of the things she quotes in her song are ironic?

 

[pirate]

Indeed, they are just unfortunate...which is ironic in a song supposedly about irony...
good song though, ironically

 

[telectrix]

more like moronic.

 

[driverman]

Can you give a reg number for that mate?
Would someone drill through the full width of a brick (102mm) to fix a TV cable?

Re drilling through cavity walls. Was just an example. Many Sky installers drill straight through cavity walls. Gas plumbers also.
Cavity wall installers installers drill into the cavity.
As for Reg No., no, I don't know. But correct me if I'm wrong, has not installing cable within external cavities been banned for years?

 

[DPG]

Don't think it's been banned, but it's definitely not a good thing to do for the reasons given before, ie. bridging the gap, and lack of support for cables (more of a problem with horizontal runs than vertical admitedly). Cavity wall ties also bridge the gap, yes, but they are designed with a drip loop so that the water drops down before meeting the inner leaf of the wall.

 

[pirate]

Unless you are wiring in the cavity in a school in Scotland, funded by PFI...they just didn't put the ties in, so no worries about fouling them, just drill and install your cables...
fkwts!