Split Concentric as a submain

[frontier219]

Hi All,

Having a little discussion with my old man over a job. The job is a domestic property, the CU is around 7 metres in cable length from the meter. There is a switch fuse around 4m from the meter, in a cellar. However, the tails are run very shoddily in an old bit of water pipe and then hanging across the ceiling. We have suggested ripping the whole lot out and running a new submain in, with an isolator at the mains. We are deciding what cable to use. I have suggested split concentric, as it is smaller and easier to run than SWA. However, my dad seems to think split concentric cable should not be used in this way, as he 'heard something about it a few years back'. We can't find anything definitive on the subject so I wondered if anyone on here could give us a bit more of a clue?

Cheers,

Dan

 

[Tidy Max]

Have any of you chaps got a photo of a split concentric you have made off? I have never terminated one but i am interested in seeing how its done. Also why would you chose to use splitcon over other cable types? I have terminated enough MICC and SWA before but never ever been asked to do a split concentric!

 

[Engineer54]

Have any of you chaps got a photo of a split concentric you have made off? I have never terminated one but i am interested in seeing how its done. Also why would you chose to use splitcon over other cable types? I have terminated enough MICC and SWA before but never ever been asked to do a split concentric!

Sorry no...


For general cabling purposes SWA is a far better all round cable with an easy glanding termination process. S/concentric has it's uses, but it's biggest drawback for common use is that the termination is not conducive to the majority of commonly used enclosures, space wise. Fine for say DNO's service cut-out's with space for the termination. But even then, if you open up that space 9 times out of 10, it'll still be a pigs ear, usually with just the sheathing removed and a bit of twisting of the single stranded concentric conductors. Unlike the DNO's installation practices, ....past the meter position everything needs to comply with BS7671 and manufactures recommendations etc, which generally means appropriate cable glands are to be used....

 

[frontier219]

Have any of you chaps got a photo of a split concentric you have made off? I have never terminated one but i am interested in seeing how its done. Also why would you chose to use splitcon over other cable types? I have terminated enough MICC and SWA before but never ever been asked to do a split concentric!

I have found this photo online. I personally would've used a stuffing gland in the bottom of the DB, but for neatness I can't see a great deal wrong with it. Anyone care to explain why this is wrong? http://www.askthetrades.co.uk/howto/public_html/split_con_db.jpg

And what measure will you use to assess whether you have done it correctly or not?

Probably my own judgment considering the various other types of cable I have terminated. However, due to the comments on here I have contacted a retired electrical engineer who I worked with briefly for advice, and he is happy to come round and have a look for me in exchange for a couple of beers.

 

[Knobhead]

Have any of you chaps got a photo of a split concentric you have made off? I have never terminated one but i am interested in seeing how its done. Also why would you chose to use splitcon over other cable types? I have terminated enough MICC and SWA before but never ever been asked to do a split concentric!

No photo’s of any I’ve done.

If you can get the heat shrink boots then all well and good, the downside is they take up too much room for use in a switch. I’ve always used self amalgamating tape and heat shrink tube, done right it looks just as good. You have to dress the concentric cores first, shrink the tube on and then tape the crutch, get the dressing wrong and it will look rough.

A word of warning, it’s all too easy to nick the neutral insulation when stripping the outer serving.

These are courtesy of DNO muppets.

 

[Silly Sausage]

Fine for say DNO's service cut-out's with space for the termination. But even then, if you open up that space 9 times out of 10, it'll still be a pigs ear, usually with just the sheathing removed and a bit of twisting of the single stranded concentric conductors.

A bit like this ...
TN-C-S or TN-S - DIYnot.com - DIY and Home Improvement
:smilielol5:

 

[Engineer54]

A bit like this ...
TN-C-S or TN-S - DIYnot.com - DIY and Home Improvement
:smilielol5:

Seen far worse but yep, that's the typical crap you'd expect to see for split concentric terminations from the DNO's

 

[Engineer54]

I have found this photo online. I personally would've used a stuffing gland in the bottom of the DB, but for neatness I can't see a great deal wrong with it. Anyone care to explain why this is wrong? http://www.askthetrades.co.uk/howto/public_html/split_con_db.jpg



Probably my own judgment considering the various other types of cable I have terminated. However, due to the comments on here I have contacted a retired electrical engineer who I worked with briefly for advice, and he is happy to come round and have a look for me in exchange for a couple of beers.

Nothings wrong as such. But i'd like to see your effort after you have completed these two terminations. I doubt you'll have that much room as shown in the link photo in the CU you are terminating too....

I still can't understand why you would want to use concentric cable in the first place to be honest. You'll be far better off using SWA cable.....

 

[frontier219]

Nothings wrong as such. But i'd like to see your effort after you have completed these two terminations. I doubt you'll have that much room as shown in the link photo in the CU you are terminating too....

I still can't understand why you would want to use concentric cable in the first place to be honest. You'll be far better off using SWA cable.....

The run to the DB is quite tight, and the cable diameter of concentric is much smaller than the equivalent SWA. This seemed like a potential solution.

 

[Tidy Max]

Interesting stuff. I would liken terminating a split concentric to trying to neatly terminate signal cables with a shared screen. Lots of heatshrink, boots and ferrells and they still look crap once done.

 

[Engineer54]

The run to the DB is quite tight, and the cable diameter of concentric is much smaller than the equivalent SWA. This seemed like a potential solution.

I'll say no more, but i'd appreciate photo's of your connected terminations once this job has been completed!!

 

[frontier219]

I'll say no more, but i'd appreciate photo's of your connected terminations once this job has been completed!!

If I decide on this method, I shall post them up! Thanks for your help.

 

[TJ Anderson]

I really don't know why someone would install split concentric now unless you had it lying around and really wanted to use it up. Even then I probably wouldn't. Since the 17th it has become even less unattractive, you can't conceal it in a wall without RCD whereas you can with SWA. You could also consider NYY-J if not concealed in wall..

 

[frontier219]

I really don't know why someone would install split concentric now unless you had it lying around and really wanted to use it up. Even then I probably wouldn't. Since the 17th it has become even less unattractive, you can't conceal it in a wall without RCD whereas you can with SWA. You could also consider NYY-J if not concealed in wall..

Out of interest, why not? My experience of NYY-J is that above 6mm it becomes VERY difficult to bend due to it being solid conductors.

 

[TJ Anderson]

Out of interest, why not? My experience of NYY-J is that above 6mm it becomes VERY difficult to bend due to it being solid conductors.

I was referring to stranded, although you are correct you can get solid also.

 

[7029 dave]

OP you are making a lotta work for your self IMO.