Advice for underground cables

[JohnW2]

I do think the point John raises is worth consideration, I for one regard ELV mixed in with twin and earths as non-compliant and shouldn't be done, but unlikely to present a danger unless something goes seriously wrong... like the cable duct fire, the interference aspect should be enough reason not to do it, however.

Indeed, and I've already made that point - I think there are good reasons for keeping LV 'power' cables and control/signally/data/audio cables apart, but that's got nothing to do with 'safety' - and still remains a problem even if the ELV cables are "insulated to 230V" (in which case proximity of cables would be compliant with regs.

As for extreme scenarios such as the cable duct fire, as I said to bernard, the regs don't necessarily help there, since they would allow the cables to be in proximity, in the same duct, if the ELV cables were "insulated to 230V", even though that would in no way reduce the possible consequences of a cable duct fire!

ELV in a trunking containing a load of 6491X conductors is a much more serious issue and likely to attract a C2 on an EICR, especially considering a lot of containment systems may contain poorly made crimped and connector blocked joints!

Indeed but, although I still think that any actual risks are still extremely small, it is a very different situation in terms of the argument I presented. Unlike insulated+sheathed cables, the regs do not regard it as 'safe' for someone to touch a 691X cable

I recently had to discourage a client's IT dept from trying to put a fibre link in the lighting trunking, put me on the spot a bit for a second or two...

Assuming yoiu are talking of 'optic fibre' I'm not sure I see any problem with that. There clearly is no safety issue and I would have thought that an optical fibre would also be immune from ant EM interference.

Kind Regards, John

 

[JohnW2]

Try google. Power cable and telephone cables have and, for some applications, still do use paper as the insulation next to the conductors.

With no outer covering and/or impregnation of the paper with something moisture resistant?

Kind Regards, John