SWA long run

[monkeyhanger]

A new build bungalow is 180m from the meter position (single phase meter in hut at the side of the road). There are 2x SWA from meter to a join next to the bungalow, where the supply then enters an external meter cupboard in 25mm SWA (new colours).

The two cables from the meter to the join are 1x 6mm 2C and 1x 16mm 2C (Red & black).

When I first entered site the building was already constructed, and that supply arrangement already present.
I have been to second fix, the builder was *sure* that the supply install had been done by a proper local firm (wont name here). After inspection it is evident that this isnt the case as there were no glands on any cable ends, no fused isolator or RCD or earth rod anywhere.

There is a static caravan and stables also on the site, which appear to be fed via the 6mm and 16mm SWAs from a join *somewhere* underground.

I have already been paid for 1st and 2nd fix, and stated that I wouldn't sign the job off unless the supply was adequate.

I have installed a 60A switch fused isolator and 100mA S type RCD & rod at the origin as a quick improvement to the situation and managed to gland the cables, however the cable run is obviously too far for 6 & 16 mm cables.

What would be the best way to proceed? To work out a suitable cabling arrangement from meter or to get the electric board to move the meter position to the bungalow?

 

[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