mixed cables in conduit

[securespark]

Sun

I agree that interference between cables is a separate issue to the segregation of Band I and Band II cables. That is covered by regs governing detrimental situations. I don't have the regs with me and can't remember the numbers.

John


Believe it or not, I installed cabling for the wall mounted TV such that all the data cables were together and the socket feed was separated. This was helped by the fact that on the back of our Sammy TV, the mains input is on its own on the left, with all the data and signal cables to the right. I always take care to segregate cables under the floor and where it is impossible to do so, I make sure they cross at right angles.

The table-top TV is also Samsung and has similarly segregated sockets. In this case, the mains lead is on its own on the left and the others are grouped together in the TVs built-in cable tidy.

On an appliance level (thinking about our TVs, it must be quite easy to segregate voltages, but I know that a lot of manufacturers don't take care to do this.

 

[JohnW2]

So in John's opinion it is absolutely fine to ignore Regulations when it suits John?

I suppose the simplest way I could answer that would be by just saying 'yes', and leaving you to remain 'shocked'.

However, my opinion remains that some common sense is required, rather than just blind adherence to regulations (which, as has been pointed out, are in no way 'mandatory', anyway).

It continues to make little sense to me that one should be worried about (insulated and sheathed) conductors coming into contact with something that is deemed safe for a person to touch with wet hands.

Having said that, I realise, and accept, that some people feel that 'the word' of rules/regulations/laws must always take precedence over common sense.

Kind Regards, John

 

[SUNRAY]

The last 2 TV's I mounted on walls have been on redundant chimney breasts. All I did was drill a big hole behind the TV and passed all cables through it to the unit below via the flue void.

 

[JohnW2]

Yes but the voltage rating of the cable would still not comply with the regs.

Maybe - but, as I've said, I, for one, have yet to find a 'voltage rating' specified for any telephone cable - but I have found at least one instance of a spec which indicates that the cable has to have >50M IR at 500V.

In any event, as I have implied, are you suggesting that one must take steps to ensure that no ELV cabler (USB, ethernet, audio, signal/control etc. etc.) cable can ever come into contact with an (insulated and sheathed) cable carrying 'mains' electricity?

Kind Regards, John

 

[SUNRAY]

Maybe - but, as I've said, I, for one, have yet to find a 'voltage rating' specified for any telephone cable - but I have found at least one instance of a spec which indicates that the cable has to have >50M IR at 500V.
Kind Regards, John

I've already replied to that with a spec that shows a CAT6 rated at 125V but a test of 1KV

... are you suggesting that one must take steps to ensure that no ELV cabler (USB, ethernet, audio, signal/control etc. etc.) cable can ever come into contact with an (insulated and sheathed) cable carrying 'mains' electricity?
Kind Regards, John

I don't believe I've said or even vaguely implied that, in fact I believe I've been saying exactly the opposite.

All I did was drill a big hole behind the TV and passed all cables through it to the unit below via the flue void.

Would I set up a sound system with a telephone line involved and have the cables all laying on the floor mixed together?... you bet.

For those involved with public entertainment we can quote massive bundles of mixed cables dumped on top of each other without any consideration and those may include microphones, triac dimmed multi KW lights, MVA feeds from generators, video and digital data ...sometimes big bundles can run a long way in very close proximity.
All of this is expected to work with no problems with no segregation.

 

[SUNRAY]

To confirm what I am saying, I woud not run a mains cable and a signal cable not rated at mains voltage in the same containment.
However I would happily run such cables in proximity if not contained (think loft space). I have a point in my roof space between timbers where a number of cables are lose laid, including:
Cooker supply,
Kitchen Ring,
General Ring,
3 outdoor socket cables,
4 or so lighting cables,
>3 TV aerial cables
Telephones,
Ethernets,
3 CAT II/CAT5 for audio distribution,
Doorbell, I assume I used CAT II,
Alarm style cables for ELV relay controls,
possibly more.
Another similar point:
45A Supply to Granny annex,
20A supply to shed,
2 outdoor socket cables,
3 lighting cables,
2 TV aerial cables
3 Satelite cables,
Telephone,
Ethernets,
2 CAT II/CAT5 for audio distribution,
Doorbell, I assume I used CAT II,
Alarm style cables for ELV relay controls,
4 UR67 type coax for 2 way radio,
Intercom, think door access - amplified & speaker also used as mic.
Yaesu FT8900 head extention,
I assume more which I currently can't recall

So yes a hotch potch of mixed cable types, different voltage ratings, different voltages and currents.

 

[JohnW2]

I've already replied to that with a spec that shows a CAT6 rated at 125V but a test of 1KV

You have, but CAT6 cable is not telephone cable and, as I've said, all I've found for any telephone cable is the requitrement for >50 MΩ at 500V.

I don't believe I've said or even vaguely implied that, in fact I believe I've been saying exactly the opposite.

You have, indeed, been saying the opposite - which is why I've been a bit confused ...

To confirm what I am saying, I woud not run a mains cable and a signal cable not rated at mains voltage in the same containment.

Fair enough, but what if there is no 'voltage rating' specified? Is it not then reasonable (through lack of alternatives) to base one's decision on the test that the cable is required to pass?

I would happily run such cables in proximity if not contained (think loft space).

What exactly do you mean by 'contained'? Are you saying that you would happy for the cables to run side-by-side, perhaps in contact (maybe even tied/taped together!) for a good proportion of the run, provided they were not within some plastic or metal 'containment'?

Kind Regards, John

 

[SUNRAY]

You have, but CAT6 cable is not telephone cable and, as I've said, all I've found for any telephone cable is the requitrement for >50 MΩ at 500V.

Indeed that particular CAT6 cable appears to be built to a better standard than CAT II so by inference testing at 1KV to give a spec of 125V hints of testing at 500V gives a spec of <62.5V.

but what if there is no 'voltage rating' specified? Is it not then reasonable (through lack of alternatives) to base one's decision on the test that the cable is required to pass?

This takes us to making wild guesses as to suitability

What exactly do you mean by 'contained'? Are you saying that you would happy for the cables to run side-by-side, perhaps in contact (maybe even tied/taped together!) for a good proportion of the run, provided they were not within some plastic or metal 'containment'?

contained within a structure provided for the purpose of intimate contact, yes including plastic or metal or wooden conduit/trunking. No I wouldn't tie/tape fixed mixed cables together but I would attach non rated cables to a conduit.

.

 

[JohnW2]

Indeed that particular CAT6 cable appears to be built to a better standard than CAT II so by inference testing at 1KV to give a spec of 125V hints of testing at 500V gives a spec of <62.5V.

I'm not sure that that 'inference' is very valid. We use testing at 500V (at most 1,000V) to determine whether insulation is 'safe enough to protect from' 230V', so why should the same 'ratio' not be applicable to any type of cable?

... contained within a structure provided for the purpose of intimate contact, yes including plastic or metal or wooden conduit/trunking. No I wouldn't tie/tape fixed mixed cables together but I would attach non rated cables to a conduit. .

I'm not sure that I understand the reason for the distinction you're making. I have plenty of instances in my house of assorted cables running for substantial distances together, undoubtedly 'in contact' for an appreciable proportion of their length, in loft spaces, under floorboards, through cupboards etc. Are you saying that you regard that as acceptable, but that it would not be acceptable if, say, I put some wooden boxing around them? If so, why?

Kind Regards, John

 

[SUNRAY]

I'm not sure that that 'inference' is very valid. We use testing at 500V (at most 1,000V) to determine whether insulation is 'safe enough to protect from' 230V', so why should the same 'ratio' not be applicable to any type of cable?

I don't have that answer, best you ask the manufacturer.

I'm not sure that I understand the reason for the distinction you're making. I have plenty of instances in my house of assorted cables running for substantial distances together, undoubtedly 'in contact' for an appreciable proportion of their length, in loft spaces, under floorboards, through cupboards etc. Are you saying that you regard that as acceptable, but that it would not be acceptable if, say, I put some wooden boxing around them? If so, why?

My, and many other peoples, interpretation of regs and MI's and interpetations of EI's/TI's I used to work to.

 

[JohnW2]

I don't have that answer, best you ask the manufacturer.

It was you, not any manufacturer, who suggested that "testing at 500V infers a spec of <62.5V.". As I implied, if that were true, it would make nonsense of all the IR testing undertaken by electricians on 230v installations.

My, and many other peoples, interpretation of regs and MI's and interpetations of EI's/TI's I used to work to.

Well, if you and/or "many other people" really believe that putting boxing around multiple insulated+sheathed cables that are at least partially in contact increases the risk of conductors of different cables coming into contact, then I'm not going to waste my time discussing that.

Kind Regards, John

 

[SUNRAY]

It was you, not any manufacturer, who suggested that "testing at 500V infers a spec of <62.5V.". As I implied, if that were true, it would make nonsense of all the IR testing undertaken by electricians on 230v installations.
Well, if you and/or "many other people" really believe that putting boxing around multiple insulated+sheathed cables that are at least partially in contact increases the risk of conductors of different cables coming into contact, then I'm not going to waste my time discussing that.

Kind Regards, John

It is not me who suggestedquoted testing a later/updated version of CAT II cable, namely a CAT6, at 8 times the rated voltage... It is the manufacturer. I know not if CAT II is/was also tested at 8 times the rated voltage, again if you do want the definitive answer, by all means contact manufacturers and report your answers back here for future proofing.

Reverting back to my earlier comment

...I have it in my mind, from my time in BT, that cat II cable is rated at 80V and on training courses it would crop up that ringing current generally accepted as being 80V +/- something possibly exceeds that.

However as a youngster much of my experimenting was done with using CAT II cable for mains only a couple of bangs to my credit.

Do the regs not specify not mixing band I and band II cabling?

 

[securespark]

I am told that the insulation on CW1308B is rated at 600 Volts but have yet to see that in print.

Neither have I, and that is probably because the manufacturers don't want it to be installed in close prox to LV cables.

 

[SUNRAY]

Neither have I, and that is probably because the manufacturers don't want it to be installed in close prox to LV cables.

Personally I compare alarm and CAT II cables and believe them to be very similar, when I have found 'rated' alarm cable it's usually 50V, on that basic I see little reason to make any assumptions CAT II is much different. When a quotable rating for CAT II cable is found I'll be delighted to know the answer and aleviate all the guesswork.

 

[JohnW2]

It is not me who suggestedquoted testing a later/updated version of CAT II cable, namely a CAT6, at 8 times the rated voltage... It is the manufacturer.

Yes, you quoted it, but it was also you who have engaged it speculative extrapolation to other types of cable.

T+E has a 'voltage rating' (Uo/U) of 300V/500V. If you were right in your extrapolation/generalisation, that would mean that it would have to be tested at at least 2,400V, probably 4,000V - yet we happily deem a cable to be safe in a 230v electrical installation if it IRs satisfactorily with a test voltage of 500V.

However as a youngster much of my experimenting was done with using CAT II cable for mains only a couple of bangs to my credit.

Same here, but I think the only (few) 'bangs' or suchlike I ever encountered were due to gross overloading of the conductor, not anything to do with voltage.

There are countless things that I have done in the past, and some that I continue to do, that I would not dream of discussing, or even mentioning here, since they are not things that I would want anyone (particularly 'the unenlightened') to think I was advocating. However, the matter we are discussing in this thread, my views about which seem to 'shock' some of you, does not, in my opinion, even remotely come into that category.

Kind Regards, John