Cable Colours

[PrenticeBoyofDerry]

Appendix 7, which of course is informative says:

Amendment No 2: 2004 (AMD 14905) to BS 7671:2001 implemented the following:
- the harmonized cable core colours

Which implies that's it known that you can only use brown/blue brown/black/grey as it was required by 514-04 of BS7671:2004

Beyond, I can't find anything else

Still can't find it, not anything that implies that old coloured cable cannot be used, only the fact it should be identified and warning notices put in place.

 

[SimonH2]

I have no problem with cores of the same colour (I'm a big fan of YY cable, which is generally all black cores marked 1,2 etc with G/Y cpc) but if they're not pre-marked cores then I could see it being a PITA

As someone used to working with multicore (signal) cables, I can also see the benefit of that. It also avoids the absurdity of core colours when you come to use a 3 core (brown,black,grey) cable for single phase.

I also spent some time as an apprentice in the shipyard. There we had some large multicores that basically went something like "red blue black in the middle, then red blue black black black ... on the next layer, then red blue black black black ... on the next layer. No numbers, you had to keep counting ...

As I understand it the UK concept of usually, on the LV system, being able to trace each phase from the substation to the end (?) connection is rare on the continent, as is the concept of the DNO (or equivalent) stating the phase rotation.

Actually we can do this from generator to end user!

Well perhaps most of the time. At my last employer, the phase rotation was wrong, which caused some confusion when rotation sensitive equipment was being installed. Mind you, one such bit of equipment I recall was a chiller (2x compressors, 3x fans) where one or two of the fans were incorrectly wired by the manufacturer I recall the fun, I was dealing with the control side so got to witness the commissioning engineers working out which bits were running the wrong direction.

 

[bernardgreen]

Compliance with BS7671 is a convenient way to demonstrate the installation is "safe" ( "safe" not safe ).

An installation could be wired using just one colour for all conductors if adequate conductor indentification is used. Adequate being that the wire is put into a labelled terminal and not actually labeled on the conductor. Lack of identification on the conductor carries a high risk of errors during initial installation and later fault finding and modifications.

While these are safe in normal use they can be very "un-safe" when later work is performed on the wiring and the person doing the work is not careful. Not reccomended for domestic installations where there is no resident electrician for its maintainance.

Therefore the use of BS 7671 is the most sensible way to achieve "safe" electrical installations in 99% of domestic properties. Mainly because BS7671 sets a standard that is ( or should be ) understood by all electricians who ever work on the installation.

 

[Iggifer]

Still can't find it, not anything that implies that old coloured cable cannot be used, only the fact it should be identified and warning notices put in place.

In BS7671 or AMD14905?

 

[EFLImpudence]

Any colour can be used as long as it is identified as per Table 51 - by colour or lettering.

Hence all these neutral lives in lighting circuits.

 

[JBR]

as with everything else that was harmonised, we should have put 2 fingers up to the EU and kept Red Yellow Blue and Black. Stupid ignoramous idiots wiritng regulations and rules from desks.

I couldn't agree more. We still have our own plugs (plug tops!) that nobody else will use despite them being the safest on several counts, so why must we comply when it comes to cable colours?

Have the EU dictators ever given a practical reason for the need to change cable colours?

 

[ban-all-sheds]

Not in the eyes of the IET you can't

Try reading 120.3 & 120.4, and then see if you can come up with an argument which says that not doing something which is regarded as introducing hazards which would otherwise not be there, and hence requiring a special warning notice to be added, is less safe than doing something which does introduce hazards which require a warning notice.

That's not to stop a DIYer using the old colours, but I doubt the NIC/NAPIT/ELECSA etc etc would be all that impressed to find old colours on an addition/modification

Depends how twattishly unwilling or unable they are to think for themselves, doesn't it.

You can actually make a convincing case to say that the law requires you to carry on using the old colours if you reasonably can.

 

[ban-all-sheds]

Still can't find it, not anything that implies that old coloured cable cannot be used, only the fact it should be identified and warning notices put in place.

What warning notice?

If you don't introduce mixed colours then you don't have to add this:

 

[ban-all-sheds]

We still have our own plugs (plug tops!) that nobody else will use despite them being the safest on several counts.

And unsafe on other counts, possibly fatally so, and only required because of a fundamentally flawed circuit design which would never be entertained for one second today if it had never been known and someone tried to introduce it.

 

[JohnW2]

And unsafe on other counts, possibly fatally so, and only required because of a fundamentally flawed circuit design which would never be entertained for one second today if it had never been known and someone tried to introduce it.

I presume you refer to ring final circuits - which I agree (in common with tobacco, alcohol and many other things) would not be entertained if someone tried to introduce them for the first time in 2012. However, what do you propose for flexible cables plugged into sockets - if one just had 16A or 20A radials, would you propose that all flexible cables (even for table lamps, small electronic devices etc., etc.) should be meaty enough to be adequately protected by the circuit's 16A/20A OPD?

Kind Regards, John

 

[SimonH2]

Not in the eyes of the IET you can't

Try reading 120.3 & 120.4, and then see if you can come up with an argument which says that not doing something which is regarded as introducing hazards which would otherwise not be there, and hence requiring a special warning notice to be added, is less safe than doing something which does introduce hazards which require a warning notice.

However, what do you propose for flexible cables plugged into sockets - if one just had 16A or 20A radials, would you propose that all flexible cables (even for table lamps, small electronic devices etc., etc.) should be meaty enough to be adequately protected by the circuit's 16A/20A OPD?

Here we go again, where's my popcorn

Do we need a couple of sticky threads so there can be a BAS style "post links" whenever the subjects come up ?

 

[ban-all-sheds]

(in common with tobacco, alcohol and many other things)

Including salt, I read somewhere once. Were it discovered by a food scientist and proposed as an additive for its preservative and flavour-enhancing properties it would fail the safety tests.

However, what do you propose for flexible cables plugged into sockets - if one just had 16A or 20A radials, would you propose that all flexible cables (even for table lamps, small electronic devices etc., etc.) should be meaty enough to be adequately protected by the circuit's 16A/20A OPD?

John - this has been discussed before, including recently, and a B16 does indeed provide fault protection for any size flex.

 

[bernardgreen]

[and a B16 does indeed provide fault protection for any size flex.

I am not sure about that, there are some thin flexes that would become very hot if carrying 16 amps for a length of time until the B16 tripped on thermal.

In a dead short fault with very high current the B16 is likely to trip before the flex becomes dangerously hot. But on an overload say 20 amps it is possible for the flex to become hot enough to be a serious hazard before the B16 trips.

Twenty amp flex on a table lamp ( less than one amp ) looks untidy and the stiffness of the flex can result in the lamp being less stable than it would be with a more flexible flex.

The fuse in the plug enables common sense use of the plug to make things safer. Unfortunately it cannot prevent the accidents caused by people who act stupidly or ignorantly but it can reduce the risks they create.

 

[EFLImpudence]

[and a B16 does indeed provide fault protection for any size flex.

I am not sure about that, there are some thin flexes that would become very hot if carrying 16 amps for a length of time until the B16 tripped on thermal.

But they won't (carry more than 16A I presume you mean).
If they did then they would not comply with the regulations regarding overload protection omission.
Single loads cannot overload the cable. That is why the posts are concerned with fault protection.

In a dead short fault with very high current the B16 is likely to trip before the flex becomes dangerously hot. But on an overload say 20 amps it is possible for the flex to become hot enough to be a serious hazard before the B16 trips.

No, not 'likely', it will.
How do you get a 20A overload on a flex?
If this were so then it does not comply and has been wrongly installed.

Twenty amp flex on a table lamp ( less than one amp ) looks untidy and the stiffness of the flex can result in the lamp being less stable than it would be with a more flexible flex.

Why would you fit 20A cable to a load of less than one amp?
How can the lamp overload the flex?
The cable must be able to cope with the fault current.

The fuse in the plug enables common sense use of the plug to make things safer. Unfortunately it cannot prevent the accidents caused by people who act stupidly or ignorantly but it can reduce the risks they create.

That is true but are the regulations written for electrical safety or a as a safeguard against stupidity ?
Obviously they are written to counteract ignorance.

 

[ban-all-sheds]

I am not sure about that, there are some thin flexes that would become very hot if carrying 16 amps for a length of time until the B16 tripped on thermal.

Flexes are appropriate for the load. If you take mad DIYing out of the equation (which you must, otherwise all bets are off), a manufacturer of an oven is not going to put a thin flex on it.

But on an overload say 20 amps it is possible for the flex to become hot enough to be a serious hazard before the B16 trips.

How does, say, a portable radio, start to draw 20A?

Twenty amp flex on a table lamp ( less than one amp ) looks untidy and the stiffness of the flex can result in the lamp being less stable than it would be with a more flexible flex.

Yes, but unless you were barking mad you would not put flex that size on a table lamp, unless you were going to put a 4.6kW lamp in it. Sticking to the ratings of lamps which could be used, what size flex would you need? And what kind of fault could occurr which would draw more current than the flex could carry but not enough to trip a B16?

The fuse in the plug enables common sense use of the plug to make things safer. Unfortunately it cannot prevent the accidents caused by people who act stupidly or ignorantly but it can reduce the risks they create.

It creates a false sense of security because of the ease with which numpties can circumvent the protection which its adherents claim it provides.

Far from being "the safest on several counts" our plugs are integral components of a system which is unsound, and which the Wiring Regulations should deprecate.