Need to put 5 core 25mm swa cable through collapsed duct

[VikGoy]

Hi i cant fit a 5 core swa cable through my ducting as its collapsed. What are my alternatives? Could i do 5 individual single core swa cables instead? Or 2 x 2core swa and 1 x 1 core?

This is for a 3 phase 100amp supply.

My electrician isnt proving helpful and says to dig up the drive so may need to find someone else but first want to get some advice to make sure i am on the right track?

The cable is around 40m long.

Thank you

 

[Why Not Indeed]

"Collapsed" to me means "can't fit any cable down it".
Hard to believe that 5x individually armoured cables would be smaller in total than a 5-core SWA. That's 5 quantities of armouring rather than one.
Are you suggesting these alternatives because somebody actually tried smaller cables and were able to get them through?

 

[jj4091]

Have you tried fastening the cable to drain rods to push it past the obstruction.

 

[Murdochcat]

can you work out where the ducting has collapsed? Then do a small excavation down to it?

Having multiple cables complicates matters somewhat

 

[pete01]

I take it above on a catenery wire isn't an option?

 

[plugwash]

IIRC some care is required with single core armoured cables to avoid eddy currents. Typically the armour is made of aluminium instead of steel to avoid ferromagnetic effects and the gland plate should also be non ferromagnetic or have slots cut in it. For the same reason it's probablly a bad idea to split the live conductors between two two-core cables.

Also a 2 core cable won't be much smaller than a four core for geometric reasons. Four circles in a circle are only 25% bigger than two circles in a circle and the armour and sheath layers are the same.

The other issue is manufacturers simply don't seem to make single core armoured cables in small sizes. Eland cable's datasheet for single core amoured for example only lists sizes down to 50mm

 

[sparkwright]

Have you tried getting a smaller cable through, then tying your cable onto it, and pulling through?

Be sure to make the knot nice and smooth, insulation tape may help matters.

 

[securespark]

My electrician isnt proving helpful and says to dig up the drive

TBF, that is often the only way if a duct is blocked.

Most people have to dig a complete channel to run a cable underground as there isn't a duct available.

If you can't get past the obstruction, Murdoch has the only solution.

Sparkright offers great advice: to make the joint smooth and snag free. Sometimes, cable jelly can help too.

Overhead is a possible solution, but it has to be a minimum height if cars will be going under it.

 

[thomp1983]

Your other option is to find a company that does moling

 

[sparkwright]

Borrow a ferret off someone, and see if he can get through.

 

[Murdochcat]

What happens if you pull the draw cable?

40 m is a long run too - has anybody done cable calcs on the size because 25 mm sounds too smal

 

[pete01]

What happens if you pull the draw cable?

40 m is a long run too - has anybody done cable calcs on the size because 25 mm sounds too smal

On my app it works out to 25mm but when you said that I did think probably 35mm.

 

[JohnW2]

Given the undesirability of the 'proper solution', if it were me I might be tempted to find a tame 'drain man' with a 'camera' he could send along the duct in order to determine the nature (and position) of the 'collapse'/blockage/whatever - since that might make it clearer what the realistic options are.

 

[sparkwright]

HAVE YOU TRIED STARTING AT THE OTHER END...?

 

[Adam_151]

Edit: In reply to John,

Personally, I'd just push it as far as it would go, and after making sure that a bit more of a shoove won't get it moving, and that the cut end is not digging into the side, I'd put a band of tape on it where it the remaining cable emerged from the duct, then pull it out and lay it on the surface. Provided the route can be seen, it should be trivial to see where you need to dig