Parallel Cables

[fattony]

I've been doing a little research into parallel cables, for example 2 x 4mm's in parallel would be able to carry 50A, it would be easier and cheaper to use 2 x 4mm's instead of 1 x 10mm

But does anyone actually do this, obviously the technical problem with this is if a fault occured on one of the two cables, fairly sure this refers to cable group though.

Its just a thought

 

[stem]

But does anyone actually do this?

Yes, the most common is called a ring final subcircuit.

And for the reason you mention is why some prefer radials.

 

[ColJack]

the larger end of the scale quite often do this as running 2 150mm's is easier to bend etc than the equivalent size in single..

in fact they did exactly this at the birmingham indoor market...
( i know because we had to jack a cable ladder into place to support them after they were installed.. )

 

[plugwash]

grouping factors will probablly kill most of the copper saving unless you take action to keep the cables apart from each other. This is more of a concern than with normal wiring because the cables will have thier load peaks at the same time.

I thought 4mm was pretty pricey stuff anyway, i'd be surprised if 2x4mm T&E was cheaper than 1x10mm T&E.

In summary the only reason i can see for doing this is mecanical handling issues with the really large cable sizes.

 

[DESL]

I thought 4mm was pretty pricey stuff anyway, i'd be surprised if 2x4mm T&E was cheaper than 1x10mm T&E.

£6.10 per hundred metres cheaper for 10mm2

 

[fattony]

stem, I know what a ring final circuit is, my question was more aimed at showers and larger circuits, I should have made it more clear.

its worth bearing in mind about 2 x 4mm's instead of 1 x 10mm it may save you an hours drive to a CEF

 

[Adam_151]

I'm not sure its exactly what they had in mind when they wrote that regulation, but there is nothing to say it can't be used in a house on cables that small (though do check what cables the terminals in different pieces of switchgear/equipment can hold)

Do however go and look at 434-03-02, particulaly the second paragraph of it, it doesn't neccessaly mean you can't do it, but you probably should do the calculation. (and a very similar thing applies to the earth, no longer being a standard circuit, it should be 'selected or calculated')

Thats the problem with getting away from standard circuits, you start having to work stuff out...