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.

 

[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.

 

[Marvo]

A cable pulling sock can also make life a lot easier if you're pulling through ribbed ducting.

 

[robd]

Final update, cable went in a treat down the twin walled duct. Thanks for all your help, very useful and now I know.

 

[Marvo]

Glad you got it in with no issues. Did you pull the 70 meters in one go? What technique did you use?

 

[robd]

Glad you got it in with no issues. Did you pull the 70 meters in one go? What technique did you use?

I used the get the builder to do it technique as I wasn't there , it was 70m in one go, the duct came with a draw wire built in and was quite a bit wider than the cable so it should have gone through easily I think. Was also a pretty straight run slightly down hill, I didn't ask them how they did it I'm only popping in occasionally as they are doing footings etc but will find out next time.