And now to correct the mistake...

[SimpleSimon]

The labourers who were putting the cable in a trench for a job have finished but left me 4ft short of the Isolator. 
So it's SWA. Best way to extend it?
Henley blocks in a metal clad box?
Know where I can find that?

 

[IQ Electrical]

The labourers who were putting the cable in a trench for a job have finished but left me 4ft short of the Isolator. 
So it's SWA. Best way to extend it?
Henley blocks in a metal clad box?
Know where I can find that?

I'd be glanding off into a metal adaptable box and using crimped joints or din connectors depending on the CSA and design current.

Is there no way you can push for a new cable of the correct length to be installed?

I really dislike joints in SWA, especially on a new install.

 

[Johnny-G]

If it was the labourer's mistake I'd be getting them to put it right.

 

[SimpleSimon]

Same.
But unfortunately the run is 100M. Under pavement and road. 
The design current is about 55A with 16mm cable.

 

[SimpleSimon]

If it was the labourer's mistake I'd be getting them to put it right.

It's too late to do that and it's easier for me to correct it.

 

[Engineer54]

Simon,

Before you do anything, check that SWA cable out, if it has been left to labours to install. You have no idea if it's been laid in the presence of sharp stones and the like, or if it's been dragged along the trench, ripping the sheath to bits in the process....
A sheath test really needs to be undertaken here, as any damage to that cable and it's going to cost a hell of a lot more to replace later than it will now.

 

[SimpleSimon]

Simon,

Before you do anything, check that SWA cable out, if it has been left to labours to install. You have no idea if it's been laid in the presence of sharp stones and the like, or if it's been dragged along the trench, ripping the sheath to bits in the process....
A sheath test really needs to be undertaken here, as any damage to that cable and it's going to cost a hell of a lot more to replace later than it will now.

That bits fine 54, I watched them lay the sand layer. I was there on Monday when the cable went down, I was at the other end putting it in and the labourer said. "yeah that's fine mate, got an extra 10ft this end." wish I checked that!
So I've got no qualms on the way it's buried. Ahhh this site is a jinx. Nothings gone right.

 

[Engineer54]

That bits fine 54, I watched them lay the sand layer. I was there on Monday when the cable went down, I was at the other end putting it in and the labourer said. "yeah that's fine mate, got an extra 10ft this end." wish I checked that!
So I've got no qualms on the way it's buried. Ahhh this site is a jinx. Nothings gone right.

That's fair enough then, if you were there and are happy with the installation, (laying in of the cable) method. I've seen some real messes of trench cable laying, by civil labourers in my time!! ...lol!!


Yeah, some sites can be just that way!!! Normally when the site/project manager hasn't got the feel or interest for the site...

 

[Knobhead]

I’d still be inclined to test the armour to earth to be sure the outer sheath is intact.

I’ve seen cable gangs do some real butchers jobs. I caught a ganger throwing 20 yards of PVC in a skip, “what’s that?”, “Oh nothing but a bit of strapping”, pity for him parts of it had BICC <600-1100V> embossed on it! God knows how much it cost his company to sort out 500M of 185mm 3½ core!

 

[Engineer54]

I’d still be inclined to test the armour to earth to be sure the outer sheath is intact.

I do that as a matter of course, on my projects. It forms part of the main contractors cable laying contractual procedures for direct buried cables. You'd be surprised just how many fail too, especially on the longer runs...

 

[johnboy6083]

I do that as a matter of course, on my projects. It forms part of the main contractors cable laying contractual procedures for direct buried cables. You'd be surprised just how many fail too, especially on the longer runs...

can a test electrode be used to test this? can an earth electrode tester be used or would an IR tester be sufficient?

 

[Engineer54]

Yes an earth rod can be used, but rarely required, there will generally be earthed metalwork and the like close to one of the ends of the cable under test.

Generally a low ohm resistance tester or IR tester is used for sheath testing, Any reading will be a fail, as it will show a connection between earth and the armouring of the SWA cable!!!

 

[Knobhead]

The last big underground run I did was a bit difficult the run was under two railway lines and two roads carrying dump trucks of up to 160 tones all side by side. 4 X 8” and 4X 6” continuous welded pipes were run to protect the cables, it was a pain running the cables in to stop the cables getting “skinned” as they entered the pipes. 300mm 3½ core don’t seem to want to play nicely when you want them to.

The up side was each pipe had an earth stud welded to the ends, once connected to the main earth bar the readings were incredibly low (can’t remember what they were).

 

[Engineer54]

The last big underground run I did was a bit difficult the run was under two railway lines and two roads carrying dump trucks of up to 160 tones all side by side. 4 X 8” and 4X 6” continuous welded pipes were run to protect the cables, it was a pain running the cables in to stop the cables getting “skinned” as they entered the pipes. 300mm 3½ core don’t seem to want to play nicely when you want them to.

The up side was each pipe had an earth stud welded to the ends, once connected to the main earth bar the readings were incredibly low (can’t remember what they were).

I know what you mean, even pulling in the lager cables into PVC ducting can shred the cables sheathing if your not careful. Which is why i make sure any underground ducting running into cable transition pits/rooms etc are provided with smooth entry/exit ''Bell Ends'' !! Always blow the ducts first too, ..to get rid of any debris that managed to find it's way into the ducting during there installation....

 

[mechelec]

Can you not just use a resin filled joint to extend. It is a bit baggy on a new install but done properly will outlast the installation.