Power/data cable in same duct for wall penetrations - issues?

[markharro]

I need to start drilling holes through our 330mm timberframe walls for ducts for cables before they are filled with cellulose insulation. Its a passive house so I want to reduce the number of holes to a minimum. I know that power and data should be keep apart ideally but would it be an issue if I used a shielded data cable in the following instances -

 

1 PV panels - these have the power cables coming from the roof but also a data cable from a special monitoring box. Any issue if I brought both through the same duct.

2 ASHP - again it need a power and data

3 EV charger - power and data needed for this I think also

4 What about power for an outdoor socket and data (poe) for external security cam

5 Power for automated sliding gate and data (if at any point in the future we can afford to instal this!)

6 power for outdoor light and data for a security cam

 

Thanks

[Conor]

Can't have a data / LV cable in same duct as a mains voltage / DC cable - if there is damage to the mains cable, power could enter the neighbouring unprotected circuit.  You can put them in individual flexible ducts within the single 100mm duct. 

[mike2016]

Unfortunately, hard to limit penetrations. One suggestion for PV is a single cable for up to two strings:

https://youtu.be/OmHtcfWUI4w

 

[markharro]

33 minutes ago, Conor said:

You can put them in individual flexible ducts within the single 100mm duct. 

That's a wide duct. I was planning on using some ducting I have which is about maybe 30mm. So what you're saying is that you can run power and data together in one duct but only if each is within their own flexible duct? So ducts within a duct?

 

What about taking multiple data cables through a single duct - I assume that wont be a safety issue and if I use shielded cables?

[Kelvin]

Keep them separate. Yes multiple data cables through a single duct is fine. Use as small a diameter ducting as you can get away with. Run extra data between hard to reach areas.
 

Out of interest, why didn’t you take more of the ducting through the slab  to minimise penetrating your building and giving you options for future proofing without drilling holes in the walls? 
 

I have 4 power penetrations using 25mm conduit, one for each elevation, two data penetrations for cameras, one for a doorbell, and one for the alarm. Everything else is ducted under the building. The only other penetration is the emergency copper pipe from HWC. The SVP is through the garage roof and I moved the PV to the ground rather than on the roof but that was largely for aesthetic reasons. 
 

I filled the ducting in with a fire resistant foam rather than standard foam that’s non fire rated. I sealed around the ducts both internally and externally using a combination of the pro-clima Roflex 20 and Extoseal which I preferred overall. 

[markharro]

HI @Kelvin we do have quite a few ducts in the slab - is it not the same issue though - you still have to tape where they enter the building?

 

I was wondering how to insulate the ducts......wont using foam mean that it would be extremely difficult to remove the cables if you needed to? I was contemplating stuffing in some sheepswool insulation.

[TonyT]

Put some sheep wool in the duct, then foam, then sheep’s wool if you want.

 

the foam seals the duct. Wool on its own wont

[TonyT]

Or use a rise sealant kit afterwards, consists of fingers of fillers inserted into voids between cables and pipes and sealed with a sealant it’s gas/air tight.

just an option

[Kelvin]

 Sealing around the ducts coming in through the slab is straightforward.
 

I’ve not decided how to insulate and seal the ducts yet. For the ducts I’ll definitely never put anything else through or ever remove what’s there I’ll fill with wool and then seal using duct sealant. For the few that I might put something else through it later I’ll use use a Rise type  kit as they are quite dear. I have two ducts that are spare just in case. I might make up something using pipe insulation and and a rubber gasket over the top then taped. 

[MoraM3]

Hi @markharro,

One option for your EV and Solar to help reduce your cables would be to use Doncaster Cables EV Ultra cable https://youtu.be/OmHtcfWUI4w and their recently released PV Ultra Cable  https://youtu.be/OmHtcfWUI4w,  both neatening things up and minimising the required penetrations.

[MoraM3]

Hi @markharro, For CCTV on my current property I've recently installed (March) a Eufy S330, their wireless solar powered solution, which works well with all cameras retaining their full charge, albeit over spring/summer.  Cheapest option was to buy direct (£799 for 4 camera kit including the base unit and a 1TB hard drive with no monthly fees).  Also noticed that Costco have recently started stocking.  I'm seriously considering also installing this system on my new build project as it will be a SIPS construction.

[markharro]

5 hours ago, Kelvin said:

 Sealing around the ducts coming in through the slab is straightforward.
 

I’ve not decided how to insulate and seal the ducts yet. For the ducts I’ll definitely never put anything else through or ever remove what’s there I’ll fill with wool and then seal using duct sealant. For the few that I might put something else through it later I’ll use use a Rise type  kit as they are quite dear. I have two ducts that are spare just in case. I might make up something using pipe insulation and and a rubber gasket over the top then taped. 

I had not been aware of this Rise sealant kit. Can anyone recommend a place to buy online?

[MoraM3]

Hi, @markharro

 

When I was down visiting the NSBRC I came across Tescon Pro Clima Roflex products which have options form cables, pipes and ducts.  You can see examples of their products on the stand in attached photo.

 

[TerryE]

We have an MBC twinwall with 300mm blown cellulosic filler between panelvent on outside and coated OSB3 racking on inside, with battened out service cavity inside that.  We use 2 × 110 foulwater piping for through-slab main ducts, but we added then added our other penetration ducts after the racking out was done, and most after filler was blown.  We use a standard process which my wife and I did ourselves (not one to delegate): 

• We decided on the placement and o.d. of each duct depending on the requirement e.g. external lights, satellite cable, ... these varied from 20-40mm.
• I then used a 60mm × 15mm masonry bit to drill a pilot hole in-to-out and then used the appropriate hole cutter inside and out to right-size the opening by pulling the masonry bit back to on the opposite side to give clearance for the cutter but other than that, returned the bit as a through guice to avoid losing the hole.
• I then cut a piece of the correct o.d. abs pipe to about 100mm longer than the hole, and notched on end with a multi-tool to form a simple cutter.  This pipe could then be slid over the bit, then hand twisted / pushed to core the hole through the insulation using the 60mm bit as a centre guide.
• Once through, each pipe was taped to the panelling and siliconed to seal, then multitooled to leave a ~10mm flange.  Once the cable / service was in place, the pipe void was foamed and siliconed to make air and moisture tight.

The whole process once practiced took about 30 mins per service opening.  

[Kelvin]

I followed a similar process. The trades just don’t understand enough about airtightness and how to achieve good results. This was re-inforced when not one of the trades (sparky, chippie, nor plumber) had ever seen anyone seal up the ducts at all let alone to the extent I did. 

[joth]

Fwiw just for variety I'll share what we did.

My build team  didn't use ducts at all. Each cable had it's own hope drilled right through (our retrofit is a mix of masonry and TF) and then individually grommeted and taped to the OSB on the inside. A couple places one grommet serves multiple cables. Some 30+ cables done this way.

 

We achieved 0.5 ACH on a retrofit, so I'm happy with the result (although in a couple places having the option to pull more cables without drilling more hopes would be good)

 

[markharro]

Thanks - I have started cutting now - pre cellulose....I am starting internally with the correct size hole cutter. Once the internal hole is cut I am using a 450mm long 10mm spade but from the inside to make a pilot hole externally. If I rest this on the bottom of the internal hole and keep it level it gives a fall from inside to out without having to think about it. I think use the hole cutter from the outside. Next thread the duct and cut to size with a flexible saw and then tape to board at each end. Its been added to my "pleasant" job list and is quite satisfying.

[markharro]

A question on my external data cables.....is it important to get outdoor rated CAT5/6 cable? Or if you run the cables in ducts do you not need to bother?

And my intention is to run up to 3 cables per wall duct - any need to use shielded cables?

 

thanks

[markharro]

On 17/08/2023 at 21:16, markharro said:

A question on my external data cables.....is it important to get outdoor rated CAT5/6 cable? Or if you run the cables in ducts do you not need to bother?

And my intention is to run up to 3 cables per wall duct - any need to use shielded cables?

Hi @joth

 and @Kelvin any views on these points as I need to make a decision pronto. thanks

[Kelvin]

If you’re placing it in proper ducting (like the Naylor electrical ducting) then you can get away with using internal ethernet cable. In every other case I’d use exterior grade cable especially if it’s exposed at any point. I’d probably still use exterior grade even if it’s ducted though. 

[joth]

Depends a bit on the application, but I'd steer for external grade cat6 minimum. And got CAT6A with U/FTP shielding if using for anything slightly unusual (high bandwidth, main WAN connection, HDbaseT, non ethernet usage like Loxone, etc).

In practice having bought a drum of external CAT6A I just used that for everything. (I actually preferred it for internal use too as the slick gloss jacket was easier to pull through narrow openings)