Cable through duct

[mhadayah]

Dear experts!

I have a plastic duct going from the house to the shed and its around 25m long through which I would like to pass a cable.

After failing to push the cable through, I've bought a 30m fish-tape. However, no matter how hard I try, I can push it through around 22m from either end.

As I do not know the path the duct takes (we've only just moved into the house and found it), I can only assume that's its an elongated 'u' shape and is getting stuck at the far end as the duct turns 90 degrees to the vertical. As I can push it a long way from either end so I am certain it is not blocked.

Has anybody any suggestions of getting it through? I have thought about getting another fish-tape and getting them to hook inside but not sure this would work as any hooks I make at the end would probably make them to difficult to pass each other to connect.

Thanks in advance,

Mark

 

[Infidel]

Depending on the size of the duct you can either try some drain rods or see if you can hire some duct rods these come in 1.5 or 2 meter lenghts and screw together and are stiffer than a tape.

 

[kenbee]

have had success in the past with similar problems by using plastic covered curtain spring, screw an eye in the end to help prevent jamming. must admit that 25metres is a lot to buy unless success is guaranteed.

 

[foxhole]

Just because you can push in 22m does not mean it is travelling that far, may be buckling up inside after a few metre and 22m is what it can hold that way.

 

[mhadayah]

The fish wire is very stiff and for sure the pressure I'm putting through it is not enough to bend it around on itself.

 

[foxhole]

Does not need to bend in on itself, could just be coiling like a spring.

 

[RedHerring2]

If you can get hold of about 4 metres of very stiff wire, about 1.5-3mm diameter should be OK or something like the armoured wire from the outside of armoured cable.

With the tape pushed as far as you can from one end, try using the stiff wire to fish it from the other end, but 3 metres is quite a long way to fish it.
The modus operandi for fishing is:
on the end of the stiff wire bend a hook, the diameter of the hook obviously needs to allow it to go in the trunking easily, but deterring the catching of any sharp edges in the trunking.
Mark off your 3 metres so you know how far in it's going.
In order to catch the tape, bend the protruding end into a starting handle shape so that you can literally cause the wire to spin in the trunking, hopefully so that the hook will catch the tape and twirl itself around the tape.

With someone on the tape end, they may be able to feel the vibrations when the two are touching/passing.
It's important that one person feeds in the tape while the other is gently pulling, assuming you've been succesful in catching it.

A little trick to faciltate the catching of the other tape is to have the leading edge of the hook, the shorter or loose end, slightly forward of the trailing end so that when you're twisting it it's more likely to catch the tape.

 

[mhadayah]

All good stuff, thanks guys, much to try!

 

[Schinklegroover]

In case you've not already achieved this, a trick I've previously seen used sucessfully is as follows:

Take a long ball of string/twine (more than enough for your cable duct) and tie something to the end of it like a largish nut and bolt, for example;
Take a tennis ball and cut a small slit in it through which (when squeezed open) you can feed the nut and bolt;
Push the nut and bolt into the ball so that the ball now is quite firmly connected to the string;
Drop the ball into the duct and blow compressed air through the duct, ensuring the string can feed freely and quickly into the duct. All being well it should quickly come bobbling out at your shed - job done!

 

[TicklyT]

Similar to above - a wad of cotton wool or similar tied to a piece of fishing line or thin cord, and suck it through with a vacuum cleaner. Pull a heavier string through with the fishing line.