Can't fish cable back through

[bayzoo]

Hi,

I wanted to slightly re-route a badly routed 6mm2 twin and earth flat cable, that leaves my utility room through the plasterboard, the wall and then to a junction box on the outside wall. I disconnected the Wago connectors in the junction box and pulled the cable through, but now can't get the dam thing to fish back through. I tested with a scrap piece of cable and it does (with some fiddling) fish back from the outside.

I'm happy to be told I need a professional, but if possible I'd like to try and rectify this myself.

First option I thought would be to use a fishing tool, but the ones I see online seem to be for smaller cables and there is very little room in the hole though the wall.

Second option is to cut the cable fish back through some outside and then reconnect in a junction box which would be visible for inspection.

Third option would be to cut the cable and then reconnect using crimps and seal with heat shrink.

Please be kind, I already feel like a plonker!

Thanks.

 

[Markyd]

sounds like a piece of masonry has fallen into the hole use a metal rod to clear it

 

[bayzoo]

sounds like a piece of masonry has fallen into the hole use a metal rod to clear it

Thanks - I did try that but can give it another shot. If that fails are any of my options worth a shot despite being more work?

 

[SJD]

Large & long masonry drill bit?

 

[pc1966]

but now can't get the dam thing to fish back through. I tested with a scrap piece of cable and it does (with some fiddling) fish back from the outside.

Can you still fish through another cable?

If not then probably hole blocked by something inside moving. (As above, try long masonry drill)

If yes then use that to pull the 6mm back through? Need a good mechanical joint, often just run/wrap side-by-side for 30cm or so and tape together, tape can also make the end more "pointed" so less to catch on edges of holes, etc.

 

[snowhead]

If the T&E is outside, use another bit of cable / flex / coat hanger pushed through from the inside and join the T&E onto it by making a loop on each end and wrap all the joint in tape to stop anything catching on the way back through the hole.

 

[bayzoo]

Thanks all

I only have a hand drill (rather than an SDS drill) but do have a 12mm masonry bit so I’ll try to make the hole clearer.

T&E is on the inside and I’m trying to fish it outside. I can just fish a cable the same type from the outside in so I can attempt to join the 2 together and then pull back through.

Silly question time, how do I put a loop on the end of a cable to join them?

 

[bayzoo]

In addition, can someone please point me in the direction of where to get suitable heat shrink should I go down this route? My web searches have made me even more confused.

 

[Lucien Nunes]

Crimps and heat shrink alone do not a complete joint make. Beware many crimps are not rated highly enough for a 6mm² circuit, nor are most suitable for the solid CPC. Good crimps that are adequate for the job require installation using a calibrated tool to achieve correct rating, and the whole should then be enclosed in a box with the cables anchored to provide strain-relief. I know a lot of sparks crimp-and-conceal without these niceties but it's not correct practice.

BTW Does the T+E itself run outside?

 

[MJPD29]

Either twist the copper together or tape it onto the cable and pull it through. Sometimes it can be fiddly fishing through a wall, clear out the hole and use a coat hanger and it shod go back through.

 

[bayzoo]

Crimps and heat shrink alone do not a complete joint make. Beware many crimps are not rated highly enough for a 6mm² circuit, nor are most suitable for the solid CPC. Good crimps that are adequate for the job require installation using a calibrated tool to achieve correct rating, and the whole should then be enclosed in a box with the cables anchored to provide strain-relief. I know a lot of sparks crimp-and-conceal without these niceties but it's not correct practice.

BTW Does the T+E itself run outside?

Ok thanks - one to leave to the pros then. No it’s connected via a junction box to an SWA cable that runs to my shed.

 

[James]

Can you borrow a large drill?
a 20 or 25mm hole is much easier to fish through.

 

[littlespark]

When they say “join” the cable to pull it through, it’s not an electrical joint.

What I do, is strip back maybe 6 or 8 inches off the outer sheath and the inner insulation.
Cut off the L and N so you’re left with the bare copper earth.
Loop it over, and twist it around itself.
Do the same with the other side, but it can be a smaller cable… it’s just for pulling through.

Squeeze the loops up with pliers to make it smaller than the size of the cable that you know the hole is big enough to take.

If it sticks, wrap tape round the joint to make it smooth… still tight, rub it up with some fairy liquid as a lubricant.

Messy job, but it can work.


I agree though that something has dropped in the hole, and it’s at such an angle that it only allows one way travel. Best to clear that somehow.

Use your 12mm bit and try and tap it through with a hammer. You’re just trying to shift a blockage, not drill a new hole.

 

[bayzoo]

Can you borrow a large drill?
a 20 or 25mm hole is much easier to fish through.

Possibly - I’ll see if I can pull it back through by fishing another cable from the outside. Failing that I’ll try and source a large drill.

 

[bayzoo]

When they say “join” the cable to pull it through, it’s not an electrical joint.

What I do, is strip back maybe 6 or 8 inches off the outer sheath and the inner insulation.
Cut off the L and N so you’re left with the bare copper earth.
Loop it over, and twist it around itself.
Do the same with the other side, but it can be a smaller cable… it’s just for pulling through.

Squeeze the loops up with pliers to make it smaller than the size of the cable that you know the hole is big enough to take.

If it sticks, wrap tape round the joint to make it smooth… still tight, rub it up with some fairy liquid as a lubricant.

Messy job, but it can work.


I agree though that something has dropped in the hole, and it’s at such an angle that it only allows one way travel. Best to clear that somehow.

Use your 12mm bit and try and tap it through with a hammer. You’re just trying to shift a blockage, not drill a new hole.

Great advice thank you - will give this a shot.

 

[pc1966]

Ok thanks - one to leave to the pros then. No it’s connected via a junction box to an SWA cable that runs to my shed.

First thing is you should avoid cutting and joining if at all possible!

If you are joining inside and in some accessible location (i.e. not buried in a wall, etc) then you have more choices for junction boxes. For example, this will easily deal with 6mm or 10mm T&E cable:

60A Junction Box 3 Terminal White

A selected range of special purpose moulded and stainless steel accessories

www.cef.co.uk

However, if it is going to be hidden then it needs to be a maintenance-free version. Those are typically designed around spring-loaded terminals like the Wagos, along with cable restraint, etc, so they will not loosen due to normal levels of vibration and temperature cycling. But you have to be careful as not all combinations of, for example, Wago boxes and terminals are rated for that, and 6mm is larger than some of the Wago family's max size rating. Also you really need to check the instructions as some specify the box has to have additional cable ties (not supplied!) to hold it shut if it is to meet the MF rating.

 

[bayzoo]

First thing is you should avoid cutting and joining if at all possible!

If you are joining inside and in some accessible location (i.e. not buried in a wall, etc) then you have more choices for junction boxes. For example, this will easily deal with 6mm or 10mm T&E cable:

60A Junction Box 3 Terminal White

A selected range of special purpose moulded and stainless steel accessories

www.cef.co.uk

However, if it is going to be hidden then it needs to be a maintenance-free version. Those are typically designed around spring-loaded terminals like the Wagos, along with cable restraint, etc, so they will not loosen due to normal levels of vibration and temperature cycling. But you have to be careful as not all combinations of, for example, Wago boxes and terminals are rated for that, and 6mm is larger than some of the Wago family's max size rating. Also you really need to check the instructions as some specify the box has to have additional cable ties (not supplied!) to hold it shut if it is to meet the MF rating.

Thanks for the advice.

Yes I’ll be cutting as a last resort, I should get it fed through eventually.

That junction box looks better than the ones I looked at. Are there any regs specific to these type of junction boxes I need to be aware of? More for my curiosity.

 

[Mike Johnson]

I usually don't bother joining and use on of these: SuperRod Cable Grip 4-6mm | Super_Rod (CRSK0406) - https://www.tlc-direct.co.uk/Products/FXSK0406.html works like a Chines finger trap, but you will need at least one rod.

 

[bayzoo]

Got it fished in the end - I did as suggested and fed another cable through from the outside and taped it to the cable I wanted pulled back through, and with a bit of fairy liquid it came out. It worked without me needing to twist any wires together, I don’t have much wiggle room to remove cable so luckily this worked.

Will give you a laugh though - I got it fished first and gave myself a high-five when I realised I hadn’t re-routed the dam thing! Could have slapped myself…

Great forum this, thanks for all your suggestions.

 

[MJPD29]

Got it fished in the end - I did as suggested and fed another cable through from the outside and taped it to the cable I wanted pulled back through, and with a bit of fairy liquid it came out. It worked without me needing to twist any wires together, I don’t have much wiggle room to remove cable so luckily this worked.

Will give you a laugh though - I got it fished first and gave myself a high-five when I realised I hadn’t re-routed the dam thing! Could have slapped myself…

Great forum this, thanks for all your suggestions.

We've all been there. Fitted quite a few commando plugs without putting the base on before

 

[Colin Jenkins 01]

Thanks - I did try that but can give it another shot. If that fails are any of my options worth a shot despite being more work?

Hello Bayzoo. An old galvanised coat hanger, straightened out, should find its way through the wall. Once that's done, tape a short length of singles flexible wire to it and pull it back through the wall. Then join the flexible wire to the cable, cover the joint with pvc tape, and pull the cable in. Good luck. Regards, Colin.

 

[bayzoo]

We've all been there. Fitted quite a few commando plugs without putting the base on before

Funny you should say that - I need to replace the Euro Schuko plug with a commando plug on my new welder…I don’t want to lose much length on the cable but might have to as the Euro plug isn’t one you can take apart.

 

[pc1966]

We've all been there. Fitted quite a few commando plugs without putting the base on before

Or those old-style rubber 13A plugs where the flex had to go through the lid first.

 

[pc1966]

That junction box looks better than the ones I looked at. Are there any regs specific to these type of junction boxes I need to be aware of? More for my curiosity.

What I like about those is the double-screws for terminating the cable, far less likely to have a poor overheating connections.

In more general terms there are several factors for any cable junction:

• The current required and size of conductors
• Support / restraint of the cable against normal movement or vibration
• Protection against the environment (e.g. water) as well as prevention of contact with the primary insulation or joints
• If it needs to be maintenance-free as inaccessible

Things like crimps, Wago, terminal blocks (choc blocks), etc are all about the electrical connection and they can vary a lot in suitability (as Lucian pointed out about crimps), but they don't cover the other points.

You must have some sort of overall junction box that provides both cable restraint and to prevent contact with the internals, and there are a lot available, usually for choc blocks or (better) Wago terminals and their equivalents. In most cases they are fine.

However, if a joint will be hidden or outside then you have less choice and they tend to be more specialised (e.g. specific combinations of Wago terminal, box, and lid fastening) and expensive (e.g. resin joints for SWA cable that can be buried, etc).

 

[bayzoo]

First thing is you should avoid cutting and joining if at all possible!

If you are joining inside and in some accessible location (i.e. not buried in a wall, etc) then you have more choices for junction boxes. For example, this will easily deal with 6mm or 10mm T&E cable:

60A Junction Box 3 Terminal White

A selected range of special purpose moulded and stainless steel accessories

www.cef.co.uk

However, if it is going to be hidden then it needs to be a maintenance-free version. Those are typically designed around spring-loaded terminals like the Wagos, along with cable restraint, etc, so they will not loosen due to normal levels of vibration and temperature cycling. But you have to be careful as not all combinations of, for example, Wago boxes and terminals are rated for that, and 6mm is larger than some of the Wago family's max size rating. Also you really need to check the instructions as some specify the box has to have additional cable ties (not supplied!) to hold it shut if it is to meet the MF rating.

This junction box says it's for a cable size 25 mm2, I'm assuming it would also be suitable for my 6 mm2 T&E or am I wrong?

 

[Risteard]

We've all been there. Fitted quite a few commando plugs without putting the base on before

Indeed. And Kliks without the cover.

 

[pc1966]

This junction box says it's for a cable size 25 mm2, I'm assuming it would also be suitable for my 6 mm2 T&E or am I wrong?

The is the maximum, usually they go down several sizes and often the data sheet will also give a minimum, though here nothing is stated. In some cases if it feels a bit empty you can strip twice the length and double-back the ends so the screws have more to grip. Quite commonly done with 13A plugs and thin flex.

However, many folks on here have the luxury of bootlace ferrules and matching crimp tool for that sort of thing. While 13A plugs are intended to have fine-stranded flex, most fixed electrical wiring accessories are only intended for solid (single-strand) or 7-strand cable, and a ferrule should be used with any fine-stranded cable like tri-rated, H07RN-F, etc.