SWA long run

[Engineer54]

Either way, the customer would have to run a larger cable. Either pay the DNO or an electrical contractor to do the work.
Alternatively the DNO could alter the medium voltage network and provide a pole mounted sub adjacent to the property, though for a run of only 180m this would probably not be cost effective.
I have done one of these jobs before, with a large property, driveway was a few hundred meters long. DNO installed supply to a kiosk on property boundary, and we ran 185mm SWA in a trench along the driveway. Either end was terminated in a poured resin joint underground and spliced onto 25mm SWA for ease of termination in house/kiosk.

2 X 95mm SWA cables would have been a cheaper option, and a dammed sight easier to handle too!! lol!!

 

[lamb]

E54:
Expense was not a major issue to the client, however dimmed or flickering lights when large loads turned on/off would have been very unacceptable.

185mm is easy to handle when its off the drum (on screw type cable jacks), onto rollers every few meters, then chucked into trench with a team of a few lads. It's when you have to lift it off the floor (eg onto ladder racking) that you will require a cable gang from the north east with arms like gorrillas.

2 x 95mm would have presented a bit of a jointing problem underground to change to 25mm (would probably require to terminated in a large feeder pillar above ground or in an underground link box)

Regards, lamb

 

[Engineer54]

E54:
Expense was not a major issue to the client, however dimmed or flickering lights when large loads turned on/off would have been very unacceptable.

185mm is easy to handle when its off the drum (on screw type cable jacks), onto rollers every few meters, then chucked into trench with a team of a few lads. It's when you have to lift it off the floor (eg onto ladder racking) that you will require a cable gang from the north east with arms like gorrillas.

2 x 95mm would have presented a bit of a jointing problem underground to change to 25mm (would probably require to terminated in a large feeder pillar above ground or in an underground link box)

Regards, lamb

WOW!! Glad to hear that your cable was installed using all the right gear!! lol!!

No jointing problem there with the 95's , they make resin joint cases for just about every configuration you can think of. If anything easier to line up the cores too, especially if you had to make joints in that 185 cable over that long a distance...

I think you'll find you that the 2 X 95's would surpass what the 185mm gave you, in just about every area. Not sure why, but Paralleling cables and it's advantages doesn't seem to have caught on in the UK. You seem to like humping the bigger cables about for some reason...lol!!!

 

[Rockingit]

Hump? Are we back on the rash thing again??

 

[lamb]

WOW!! Glad to hear that your cable was installed using all the right gear!! lol!!

No jointing problem there with the 95's , they make resin joint cases for just about every configuration you can think of. If anything easier to line up the cores too, especially if you had to make joints in that 185 cable over that long a distance...

I think you'll find you that the 2 X 95's would surpass what the 185mm gave you, in just about every area. Not sure why, but Paralleling cables and it's advantages doesn't seem to have caught on in the UK. You seem to like humping the bigger cables about for some reason...lol!!!

Makes you feel like a real man!
95mm, my bootlaces are thicker than that, LOL.
I also use to do electrofusion work on large underground PE pipelines, now some of those joints were a real wrestling match, hehe.

 

[Knobhead]

Got to admit I would have gone for 2 X 95. A breach joint is easy enough using epoxy joints and mechanical connections.

Thinking about it I think the last breach I did was 95mm PVC SWA in to a 37/072 PILC DWA, enjoyed doing it. It was old meets the new, the PILC was 70 years old.

 

[Geordie Spark]

E54:
Expense was not a major issue to the client, however dimmed or flickering lights when large loads turned on/off would have been very unacceptable.

185mm is easy to handle when its off the drum (on screw type cable jacks), onto rollers every few meters, then chucked into trench with a team of a few lads. It's when you have to lift it off the floor (eg onto ladder racking) that you will require a cable gang from the north east with arms like gorrillas.

2 x 95mm would have presented a bit of a jointing problem underground to change to 25mm (would probably require to terminated in a large feeder pillar above ground or in an underground link box)

Regards, lamb

Wheyayeyerbuggerman !!! we may not be very bright up here, but we can all lift heavy weights !!!!

 

[richy3333]

Either-way when that existing, wrong SWA comes out of the ground think of the £'s you'll get for the scrap

 

[Welchyboy]

So 2x 95mm 2/3core SWA in parallel instead of say a single 185mm SWA?


this would be an acceptable/preferable method of supplying an installations sub main given the circumstances?

not judging or commenting, just for my own interest and information for future reference, i havent heard of this method really used before, but then again ive never been involved in such an extreme situation, im assuming that this is acceptable because even if one 95mm core became disconnected the CCC would still be miles within limits of the fuse

and just to clarify, for example, supplying the run in 185mm swa then underground resin joint at either end reducing down to 25mm swa to terminate into switchgear

resulting in a nice low value for VD and ZE?

 

[Engineer54]

Of course it's acceptable and in the right situations very much preferable!!!

Do a comparison, between the two methods, and see for yourself.

It's not really rocket science to use 2 smaller cables to achieve what a far larger cable can. The lager the CSA of a cable gets, the lower the increase in Current carrying ability it has. What i mean by that is, ... if you look at a 70mm cable then compare with 2 x 35mm, you will see the 2 X 35mm cables will carry far more current than the 70mm cable, and will also have a better volt drop figure too....

 

[Rockingit]

So, would you just literally run them side by side and terminate both ends together back as one? And, if so, presumeably take your test readings by the same method, except for IR which would be separate?

 

[Welchyboy]

Eng54

Take this example for instance, from what i found on a PIR on a village hall recently, 60A switched fuse supplying an old wylex board about 25 meters away
supply from Sw/f was 2x 6mm twin and earth taped together throughout the run. install method C
now i considered this a code 2 deviation, with my arguement being if a conductor was disconnected form one of the cables the supply would still be maintained but the CCC halved and now under-rated (and it was a right old bodge up anyhow)

was that justified in that case you think?

 

[Knobhead]

No problem, it’s done a lot in distribution systems. I know I’d rather run 2 X 95mm’s rather than an 185mm. And as E54 said better current carrying capacity.

It’s also got my ares out of the fire a couple of times. A few times I’ve had one cable in a parallel run damaged. Disconnect the damaged cable at each end then power the good cable back up. All be it with restrictions on loading. You then have the opportunity to repair the cable as and when convenient. Eeerr well, when you’ve found the fault, it’s usually the time consuming bit of the job. I’ve spent many an hour wandering around with a CAT cable locator, great in summer, not so in winter.

 

[johnboy6083]

i agree with tony and E54. with a lot of newer control panels ect, there is not a lot of room in which to gland and terminate your cable. Smaller cables are a lot easier to bend require less room to do so.

read sections 433 nd 434 in the BRB to find out more regarding overload protection and fault protection.

 

[Welchyboy]

Eng54

Take this example for instance, from what i found on a PIR on a village hall recently, 60A switched fuse supplying an old wylex board about 25 meters away
supply from Sw/f was 2x 6mm twin and earth taped together throughout the run. install method C
now i considered this a code 2 deviation, with my arguement being if a conductor was disconnected form one of the cables the supply would still be maintained but the CCC halved and now under-rated (and it was a right old bodge up anyhow)

was that justified in that case you think?

^^^^
REG 433.4.1 oops! may have to scratch that one off the remedials list!

 

[Engineer54]

Eng54

Take this example for instance, from what i found on a PIR on a village hall recently, 60A switched fuse supplying an old wylex board about 25 meters away
supply from Sw/f was 2x 6mm twin and earth taped together throughout the run. install method C
now i considered this a code 2 deviation, with my arguement being if a conductor was disconnected form one of the cables the supply would still be maintained but the CCC halved and now under-rated (and it was a right old bodge up anyhow)

was that justified in that case you think?

Are you really being serious here?? You code 2 a paralleled supply cable, just in case one cable may be, ...or become disconnected??

Sorry, i've never heard such a load of old rubbish, not for a long time!!! You could apply that daft philosophy to just about any connected cable on any installation..... Do you apply these too, ....What if, it could, maybe, possible, perhaps??

 

[Engineer54]

Welchyboy,

On many of my projects (and the same on any larger project) it is not uncommon at all, to see paralleled main supplies/ sub-main supplies. I'm not talking two cables paralleled, i'm talking in the realms of 10/15 and more, and that is per phase and per neutral!! Can you imagine the size of a single multi core cable that would be needed to supply that main or sub-main??

When run in that sort of magnitude, they will be singles, run on cable tray in trefoil grouped formations and split for dressing/connection a couple of metres away from the Switchboard/TX or whatever. Parallel feeding is, ...and always has been a standard cabling practice on short, medium and long runs where high current carrying requirements are to be met. They are also used to reduce cable cost and labour costs on longer runs of supply cables...

 

[Knobhead]

View attachment 9185

Cheer up E54

 

[Marvo]

If you run parallel cables it might have implications for the PSCC of the circuit which might dictate a higher KV rated mcb at source. This can also make issues with cascading further upstream. Unlikely to be an issue with long cable runs but it'sa problem I've come across with very short supply cables especially when you close to the supply transformer like in shopping centers etc. Just another consideration

 

[Welchyboy]

Are you really being serious here?? You code 2 a paralleled supply cable, just in case one cable may be, ...or become disconnected??

Sorry, i've never heard such a load of old rubbish, not for a long time!!! You could apply that daft philosophy to just about any connected cable on any installation..... Do you apply these too, ....What if, it could, maybe, possible, perhaps??

Well to be honest i mostly undertake domestic and light commercial works and around 99% of the work i have under taken has been 200A TPN or smaller so its not really an area im very experienced in and have never in the past needed to use parallell cabling, the issue with the PIR, yes i was wrong looking back at it now and should of referred to BGB if in doubt but the reason this supply was installed how it was, was not due to loading issues or volt drop or current capacities of cables, it was beacause the bloke who did it couldnt be arsed to get any 10mm and instead just used what he had in his van

anyhow i was wrong to mark it like i did and i stand here today a more elightened and wiser man than i was yesterday, which is why i took an interest in this thread in the first place, so thank you for the reprimand