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Cable type to use

Hi,

A relatively minor issue but your thoughts will be appreciated.

An existing domestic installation is to have the internal service head moved to a new external meter box. A new 10m long 80-100A 1ph distribution cct will therefore be run from a switch fuse in the meter box (contentious, perhaps) to the CU.

The meter box will be approx 2-3 feet off the ground. The proposed cable route is to drill through the wall below the meter box up to approx a foot of the ground, that will go through into the basement.

The distr cct will be in the order of a 25mm2 cable. The issue is then the type of cable to use?

- A 3 core SWA will be difficult to use because its bending radius will be too great to get into the meter box; and drilling downwards to lessen the angle is inadvisable given water could track down the cable into the basement even after packing with sealant but which may deteriorate.

- Tails could be used, that are mechanically protected in e.g. conduit emanating from an adaptable box.

- Of interest though (due to not having used it before) is thoughts on using split-concentric in this scenario (which table F5 of GN 1 lists for general use) - given the short distance between the hole and the bottom of the box, perhaps it will be easier to bend up into box.

So thoughts please on using split-concentric.

Thanks.

Parents
  • Split concentric is often used and should prove satisfactory in service. Two caveats though, firstly all live conductors, including the neutral, now require double insulation. The neutral wires in split concentric are "covered" rather than "insulated"  Secondly, the larger sizes of split concentric including 25mm generally have a solid aluminium core. Are you certain that the terminals at BOTH ends are suited to aluminium conductors ? Many are for copper only. The solid aluminium conductor is also less flexible than the stranded copper formerly used.

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  • Split concentric is often used and should prove satisfactory in service. Two caveats though, firstly all live conductors, including the neutral, now require double insulation. The neutral wires in split concentric are "covered" rather than "insulated"  Secondly, the larger sizes of split concentric including 25mm generally have a solid aluminium core. Are you certain that the terminals at BOTH ends are suited to aluminium conductors ? Many are for copper only. The solid aluminium conductor is also less flexible than the stranded copper formerly used.

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