Cable duct for under ground SWA

[robd]

Afternoon all,

On an extension job, customer wants a cable run to a pond which is 70m from the house, for oxygenation and some lights.

There are quite a bit of groundworks going in including all the drains which will be running downhill to said pond and are being dug currently.

Builders want power to go down whilst all the digging is being done. Question is means of getting down there, usually I'd ask for standard 500mm trench but in this case it will probably go in to the side of drains well below surface. What I had thought is SWA inside Black electric cable polyduct as per link here:

Electric Cable Polyduct 32/37mm Black Smooth Single Wall - 100m | Drainage Superstore® - https://www.drainagesuperstore.co.uk/product/electric-cable-polyduct-3237mm-black-smooth-single-wall-100m.html?gclid=EAIaIQobChMIoKCC_KzC3QIVAvhRCh1uxweOEAkYAiABEgL79PD_BwE

Just wondered a. if anyone had a better idea and b. if you've used the duct before is there somewhere else it can be bought short of phoning round builders merchants.

Thanks in advance.

 

[Midwest]

Give you a bump. Thats a hell of a way to run a swa, no chance of doing it subsequently. Think you might need rigid ducting of some sort with access points.

 

[Pete999]

Afternoon all,

On an extension job, customer wants a cable run to a pond which is 70m from the house, for oxygenation and some lights.

There are quite a bit of groundworks going in including all the drains which will be running downhill to said pond and are being dug currently.

Builders want power to go down whilst all the digging is being done. Question is means of getting down there, usually I'd ask for standard 500mm trench but in this case it will probably go in to the side of drains well below surface. What I had thought is SWA inside Black electric cable polyduct as per link here:

Electric Cable Polyduct 32/37mm Black Smooth Single Wall - 100m | Drainage Superstore® - https://www.drainagesuperstore.co.uk/product/electric-cable-polyduct-3237mm-black-smooth-single-wall-100m.html?gclid=EAIaIQobChMIoKCC_KzC3QIVAvhRCh1uxweOEAkYAiABEgL79PD_BwE

Just wondered a. if anyone had a better idea and b. if you've used the duct before is there somewhere else it can be bought short of phoning round builders merchants.

Thanks in advance.

Some Garden is that.

 

[Strima]

Twin wall cable duct: 50mm x 50m Black Twinwall Electric Cable Duct | Drain Depot - https://www.draindepot.co.uk/50mm-x-50m-black-twinwall-electric-cable-duct.html

Also pull in a couple of draw cords for future use if required.

Seal duct ends with resin pack: Resin Pack 14B - Polyurethane Duct Sealing System - http://www.alh-systems.co.uk/resin-pack-14b-polyurethane-duct-sealing-system

 

[Marvo]

It would be a lot cheaper just to bury SWA direct in the ground alongside the builders piping unless they've specified ducting for some reason.

 

[chris gray]

Tbh the question should be: will the ground workers have a leg to stand on when they find my cable has been laid in their trench before they had chance to lay their pipe work

 

[bigspark17]

Why the expense of the duct? Buried direct is perfectly acceptable.

 

[Midwest]

Why the expense of the duct? Buried direct is perfectly acceptable.

Not in all conditions, according to some manufacturers;

Electric Cables in Water? Cables Installed in Waterlogged Condition - https://www.whyprysmian.co.uk/underground.html

 

[Pete999]

Tbh the question should be: will the ground workers have a leg to stand on when they find my cable has been laid in their trench before they had chance to lay their pipe work

Don't know but you may find your cable in lots of little pieces.

 

[robd]

Tbh the question should be: will the ground workers have a leg to stand on when they find my cable has been laid in their trench before they had chance to lay their pipe work

Pipe is already in, cable is an afterthought

 

[robd]

Why the expense of the duct? Buried direct is perfectly acceptable.

There's quite a bit of rubble etc in the stuff that's been dug out and will back fill after. I didn't want to run the risk of cable being pierced.

 

[robd]

It would be a lot cheaper just to bury SWA direct in the ground alongside the builders piping unless they've specified ducting for some reason.

Just wanted to give it a bit more protection, as above. Don't want to dig a 70m trench if it gets damaged, 7m is bad enough.

 

[robd]

Some Garden is that.

Pond is only halfway down

Give you a bump. Thats a hell of a way to run a swa, no chance of doing it subsequently. Think you might need rigid ducting of some sort with access points.

Was going to feed cable through before burying rather than after and not planning on using duct for anything else so isn't access point a bit overkill?

 

[davesparks]

Why the expense of the duct? Buried direct is perfectly acceptable.

If you trust the people burying it to bed it in soft material correctly and not cover it with rubble and other rubbish that could damage the sheath.

 

[robd]

Not in all conditions, according to some manufacturers;

Electric Cables in Water? Cables Installed in Waterlogged Condition - https://www.whyprysmian.co.uk/underground.html

Why the expense of the duct? Buried direct is perfectly acceptable.

Living where we do the soil is clay, the house comes in the local authority Broads Authority so would expect the ground to be sodden at that depth in the winter, it's a pretty deep trench.

 

[robd]

If you trust the people burying it to bed it in soft material correctly and not cover it with rubble and other rubbish that could damage the sheath.

This is my main concern.

 

[chris gray]

Make sure it’s smooth sided duct. We’ve just tried pulling a 50mm 4c through a 120mm ribbed duct! Even though it’s flexi duct we’ve had endless problems!!

 

[SJD]

I've used duct from the drainage superstore for SWA, but somewhat larger - I used 50/65 recently, smooth inner wall, ribbed outer. I think 32/37 is maybe a bit small.

Over shorter lengths (15 to 20m) it was actually easier to push the SWA through the duct (6mm/3-core), rather than pull it. I don't think you'd want to try pulling/pushing the SWA through before it is laid.

 

[davesparks]

Make sure it’s smooth sided duct. We’ve just tried pulling a 50mm 4c through a 120mm ribbed duct! Even though it’s flexi duct we’ve had endless problems!!

Get a ball a little bit larger than the cable and drill a hole through it. Fit the ball over the pulling rope at the point where it joins the cable and tape it up so there’s a smooth surface between the ball amd the cable. The ball should give a nice rounded surface to ride over the ridges in the duct.

 

[robd]

Thanks for all the replies really helpful. Builder was picking up a twin walled 50mm duct today so will call by tomorrow and see what the score is.