Supporting cables.

[bremen1874]

Having lifted my landing floor to fix a central heating problem I’ve found that there’s a run of approximately 10 T&E cables that goes along the length of the upstairs landing.

The cables are loosely bundled together and supported about once a metre by straps made by nailing short lengths of T&E across the bundle. In many places between the straps the cables have sagged and are resting on the downstairs ceiling.

I’d like to improve the cable support before I put the floor back down and was wondering about the best method.

Would it be acceptable to keep the cables in a bundle (or a couple of bundles) and reattach them using cables ties and cable tie mountings, or should the cables be clipped individually?

Thanks.

 

[rjb]

Cables grouped de-rates cable considerably as they cannot radiate heat away from themselves so can only carry less curent.

Table 4B of the regs gives factors for such groups of cables.

It would be much better to clip them one cable width apart.

 

[bremen1874]

Thanks.

I've looked at clipping the cables individually and found two potential problems...

1. Laying all the cables side by side would take up almost the entire depth of the beam. This would place some of the cables very close to either the downstairs ceiling or the upstairs floor.
2. There's a fair chance the cables are twisted within the existing bundle so that they won't lay neatly along the beam.

 

[DESL]

Put some noggins across the joists - 2" by 2" will suffice to keep them 50mm above ceiling.