mixed cables in conduit

[john4703]

I need to put in an extra phone socket and want to avoid running the 6 core cable up a wall. There is a length of plastic flexible conduit with three single core 2.5mm cables in it. These supply a socket next to where I need the phone socket. Is it legal to run the phone cable in the same conduit? It seems wrong but I am wondering if it can be done and is safe.

 

[winston1]

Don’t know about legality as the regs are not statutory anyway. But it is generally accepted that if you run comms cables in the same conduit their insulation should be as good voltage wise as the power cables. So I would say don’t do it.

 

[chivers67]

Normally you have separate routes for comms and power, you could get a bit of inductance into the phone cable. You could use screened cable as an option

 

[RandomGrinch]

If you were going to risk it, you could use a good quality CAT6 cable instead of a flimsy telephone cable.
If you did that, you would also have some degree of future proofing, when phones
inevitably move to VOIP systems!

 

[john4703]

If you were going to risk it, you could use a good quality CAT6 cable instead of a flimsy telephone cable.
If you did that, you would also have some degree of future proofing, when phones
inevitably move to VOIP systems!

The only reason I need the extra socket is that my wife keeps falling over and the local NHS have suggested a personal alarm. If she pushes it she can then talk to control viw a single box that seems to have a speaker and microphone. The only phone socket in the house is under the worktop in my study so I want another in a more central position. (I use cordless phones so only needed the one socket)

 

[JohnW2]

Don’t know about legality as the regs are not statutory anyway. But it is generally accepted that if you run comms cables in the same conduit their insulation should be as good voltage wise as the power cables. So I would say don’t do it.

If you were going to risk it, you could use ....

The true level of (electrical) 'risk' is close to zero - as I have demonstrated in the past even '50V signal (PVC) cables' and suchlike usually IR fine at 500V (and usually also 1000V), even after several years of immersion in brine!. I would be more concerned about inductive/capacitive pick-up of mains 'hum' - but one could determine by 'suck it and see' whether that was an issue.

For what it's worth, I certainly have telephone and/or other comms cable within the same ducting/trunking as 'mains' cables, without any problems.

Knd Regards, John

 

[RandomGrinch]

The true level of (electrical) 'risk' is close to zero

Yes, I totally agree
Although the use of singles for the mains with one less layer of insulation and a flimsy telephone wire may make the risk an infinitesimally small amount higher!

 

[john4703]

Yes, I totally agree
Although the use of singles for the mains with one less layer of insulation and a flimsy telephone wire may make the risk an infinitesimally small amount higher!

I can agree, but singles are so much easier to pull into conduit than twin and earth. I'm starting to think the sensible way would be to add an extra layer to the telephone wire, I could add a layer of heat shrink to it (I am thinking what I have available and I've a few coils of heat shrink)

 

[sparkwright]

Is the floor carpeted?

Telephone wire does fit under carpets between the gripper strips and the skirting board.

You would NOT put 230v mains cables under carpet of course.

 

[JohnW2]

Yes, I totally agree Although the use of singles for the mains with one less layer of insulation and a flimsy telephone wire may make the risk an infinitesimally small amount higher!

I aso totally agree with what you say - and am not at all concerned about infinitesimally small increases in near-zero risks

Kind Regards, John

 

[JohnW2]

... I'm starting to think the sensible way would be to add an extra layer to the telephone wire, I could add a layer of heat shrink to it (I am thinking what I have available and I've a few coils of heat shrink)

That obviously would not do any harm, but the only thing it would really be guarding against would be mechanical damage to at least one layer of the telephone cable's insulation during the 'pulling in' process - as I've said, I'm sure that the insulation of the phone cable, if intact, would (in reality/practice, not 'official ratings'!) be fine!

Kind Regards, John

 

[securespark]

I aso totally agree with what you say - and am not at all concerned about infinitesimally small increases in near-zero risks

Kind Regards, John

What other non-compliance a with the rega would you encourage?

 

[JohnW2]

What other non-compliance a with the rega would you encourage?

What reg would it be that relates to "infinitesimally small increases in near-zero risks" ?

Kind Regards, John

 

[securespark]

Don't side-step the question.

You know very well in this case we are talking about the installation of Band I and Band II cables together in the same cable enclosure.

Even when insulated to the higher voltage, you have to take into account detrimental effects.

One also has to take note of the manufacturers' data. You can't just advise people to ignore the regs based on your experience.

 

[winston1]

You can't just advise people to ignore the regs based on your experience.

Why not? The regs are non statutory and sometimes don’t make sense.