AV cables in solid wall - what the regs say?

[Deuce]

Hi all,

Just being cheeky and asking for some advice really..

In my new house, we have solid walls throughout - great, but not so great for my home cinema kit. My issue is that whilst I would can chase the AV cables to wherever they need to be, I would prefer to do it in such a way that leaves the system open for future expansion. In the previous house we had stud walls and I was able to route flexible trunking between wall ports and pull through/swap whatever I needed.

In an ideal world, I would do something similar by cutting into the block, embedding some solid wall PVC trunking/pipe, and plastering back over. I can keep all my cuts continuous in either the horizontal or vertical, but my concern is what depth I'm allowed to cut into the block wall. Ideally I would need to go in to the block in 50x50mm channels to allow the space to run multiple feeds including moulded connectors... I'm not as regs savvy as you lot so thought I'd just ask the experts

NB for the mains power I'm chasing along separate routes to run the mains independently from speaker flex/hdmi etc.

 

[sheppertonspark]

You've got me looking now ! Part A Building regs. Vertical chase maximum 1/3 of the inner leaf. Assuming 4" leaf thats a 1.3" chase in the wall (not the plaster or whatever finish there is). Sorry to revert to "mm" now but that gives a minimum of 18mm (ish) finish to play with, you should just get away with the following and still comply with Part A Building regs. I normally chase in 100 X 50 plastic trunking from low level to behind the tv. Use a couple of 47mm(or 35mm) deep flush twin boxes fixed "landscape" and remove the top/bottom, HDMI ends fit through easily. Fit double euro plates with brush inserts (cheapest at S.fix). It is important to fit EML (expanded metal lathe) over the trunking because the finish is extremely thin and will crack if not used. Hope this solves the vertical, I'll let you work out the horizontal but including the wall finish I think you will find 20mm conduit easily complies with the 1/6 horizontal chase in the inner leaf. 20mm should be big enough for speaker cables and the like.
Here's hoping you have thick plaster already !

 

[sheppertonspark]

But also, not very easy to prove a bridge has been formed

This could be very useful as I can cut out enough to feed some pipe through the cavity to carry the feeds, and then re-instate the interior leaf using a new bit of cut block. The end result would be a safe route for cables and a 'good as new' wall structure

I have a project meeting with our structural engineer at work on Tuesday, I'll take advantage of that to run this by him too...

 

[sheppertonspark]

The big damp patch on the wall will tell you if you been succesful or not

 

[Deuce]

You've got me looking now ! Part A Building regs. Vertical chase maximum 1/3 of the inner leaf. Assuming 4" leaf thats a 1.3" chase in the wall (not the plaster or whatever finish there is). Sorry to revert to "mm" now but that gives a minimum of 18mm (ish) finish to play with, you should just get away with the following and still comply with Part A Building regs. I normally chase in 100 X 50 plastic trunking from low level to behind the tv. Use a couple of 47mm(or 35mm) deep flush twin boxes fixed "landscape" and remove the top/bottom, HDMI ends fit through easily. Fit double euro plates with brush inserts (cheapest at S.fix). It is important to fit EML (expanded metal lathe) over the trunking because the finish is extremely thin and will crack if not used. Hope this solves the vertical, I'll let you work out the horizontal but including the wall finish I think you will find 20mm conduit easily complies with the 1/6 horizontal chase in the inner leaf. 20mm should be big enough for speaker cables and the like.
Here's hoping you have thick plaster already !

That's really useful - so you find that it's generally possible to chase 50mm deep trunking without fouling the 1/3 rule? I can see that at worse it's a couple mm beyond 'allowable' taking into account the finish plaster.

So long as it's not something that a surveyor would be triggered by, I'm frankly happy to do it..

 

[sheppertonspark]

Yes, generally meets requirements.

 

[sheppertonspark]

While you're at at it. Switched fuse spur at low level feeding socket behind TV, job's a good un.

 

[pirate]

If the moulded plugs are the worry, use cat6 and terminate as you require. Run 2 or 3 everywhere. Also, a tip for HDMI, use the ribbon flat cable, put 3 in the trunking, they take up no room! Put them in before snapping the cover on.. .if you have a failure (unlikely) just switch to another one, and as suggested by sheppertonspark above, use brush-plate outlets, allowing up to 8 or 10 cables through.

 

[Deuce]

While you're at at it. Switched fuse spur at low level feeding socket behind TV, job's a good un.

But... why? It's a plug in (fused) appliance, why fuse at spur too?

 

[sheppertonspark]

So you can isolate it at night easily, (my mate is a fireman !!)

 

[ruston]

1. [QUOTE="sheppertonspark, post: 1482451, member: 17777 So you can isolate it at night easily, (my mate is a fireman !!)[/QUOTE]

As I have got older and stuff is getting crappier (sic) I do the same.

 

[Squid]

So you can isolate it at night easily, (my mate is a fireman !!)

Just pull the main fuse for the whole house............

 

[DefyG]

I normally chase in 100 X 50 plastic trunking from low level to behind the tv. Use a couple of 47mm(or 35mm) deep flush twin boxes fixed

Used to use 50mm trunking when Scart leads were the norm but usually find 40mm is plenty now and 25mm is usually enough but second the ribbon type HDMI's

 

[Deuce]

So you can isolate it at night easily, (my mate is a fireman !!)

Are you saying fit the FCU simply to give an accessible switch (isolation point) then? If so I could simply extend the power cable to the TV straight to a low level FCU, no need for plug+socket at all.

 

[Deuce]

I just want to add to those kind enough to have replied, that whilst I'm slightly taking advantage by talking about AV stuff on these forums... I do fully expect that very soon a lot of sparks will be getting asked to run AV/network/signal on a regular basis. Such connections become increasingly vital for people, and many don't have the basic skills required to do the work themselves.

 

[Squid]

Have you tried AVforums.com?

 

[Deuce]

Have you tried AVforums.com?

I'm a regular

But of course, those guys are not used to worrying about regulation so much...

They can tell you about sonic reflection etc, but they can't offer much in terms of regulation