"Leave Colour Changing to Chameleons!"
The problem with humans is that when something has worked successfully for many years, they change it! And it is no different in the UK and Ireland. The primary colours in electrical installations are being changed to 'harmonize with Europe'. I personally think this is absolutely crazy! And mark my words, it will result in many unnecessary deaths!
Let's first investigate the colours that have been used in the UK for years. I personally like to couple them to resistor colours (I might be too young to remember, but I suspect that such colours have been around longer than phase colours). Black is zero, red = 2, yellow 4, and blue 6. This makes life logical as this means each of the 'colours' (bar black) has a value. All sorts of 'systems' come to mind to couple the values to a property of a phase.
But, which ever 'memory system' you adopt to link colours to phases, black is still zero making it an ideal colour for Neutral. Black is known in the printing trade as a 'non-colour' as it absorbs (analogy here is it could be likened to the return path). All other colours reflect to some degree or another (so they carry voltage). Based on this, it does not make sense to change logical thought!
To call black anything but Neutral leads to mistakes. I can recall a complete computer system being blown to smithereens because of it! The power protection on the computer system would clamp any N-E voltage above 25V. When the Black and White (what was intended to be Live and Neutral respectively) got swapped, the part that 'let go' was the Earth - and the 230V was then disseminated throughout all the peripherals and blew every port of the pretty expensive mainframe!
The Earth being weaker than it should have been also caused the cabinet of the mainframe to rise far above ground potential meaning someone could have been seriously hurt (thankfully, no-one was). OK, so harmonization may alleviate this as everyone will now know that black is stupidly called Live, but the only relationship this has to any logic is that black is called "death".
If one investigates the above table closely, it will be noticed that an older trained sparky and a more up to date one working on an installation together could lead to a few domestic items being strapped to 400V (and if you cannot work it out, please do some serious further learning... Now!).
There are some who are saying this change is nothing more than a means to generate work as there are going to lots of devices and installations that will need to be changed. Also, can you imagine how many training courses will have to set up too! Even more employment!
But there is another argument that must be brought to the fore. What have the Health and Safety Executive, which have such a grip on working practices in the UK, said about this? This must call into question whether they exist for the benefit of everyone, or just themselves!
The scary part is it appears the UK has already signed up to this colour change and that they have only (probably on safety grounds) managed a "stay of execution" ('scuse the pun!) till April 2004. This does not leave a lot of time to propagate the changes throughout the ranks!
So this is my little bit towards trying to save lives. Though there is an old rule that says one should treat all wires as live, I suppose it is now more true than it ever was! I will be making a positive move and praying for everyone's safety.
Many may ask why there is such distaste shown at the proposed BS7671 changes, well, most of us have seemed to find out by accident this was being done. It's not as if I am against using a common colour code as it does have merits of safety.
It's the fact that till now there has been no public awareness campaign. I can only go by personal experience when the "Brown & Blue" got adopted into domestic use, there were adverts in every available media. With this change - nothing!
Maybe everyone is waiting for the "change-over period" to begin. New installations must comply as of April 2004, but all change is only required by 2006. Hopefully, during this time, electrical outlets will have adverts plastered all over their trade counters, and also have the cable with the new colours on the shelves!
If this can be guaranteed, then I too would cautiously welcome the harmonization of colours.
Till then, don't assume a single thing!
Let's face it; You would not like to be in the middle of a professional indemnity law suit because you only did what the regulations said you should, but someone died because of it! That's the law. If you do something, regardless if it's the correct thing, and someone is hurt as a direct result, you're to blame. Yip, the people who caused this change to happen did not think of this!
However, there is something you can use to your advantage! And it's even allowed within in the ammendments to BS7671. Imagine, they have even allowed you to rebel against the full whack of changing colours. How kind!
You only need use one colour!
I have already seen such a board where the designer was not prepared to accept the consequnces of using Black as a Live, and the whole board was Brown for Live and Blue for Neutral (obviously Green/Yellow for Earth). Now, c'mon, when one sees these colours, with having used them for years in domestic environments, there is very little chance of confusion.
The only requirement here is to identify the various phases, and this can be done with any means you wish! This chap simply left phase A as Brown, and then used electrical tape wrapped on the ends of the cables; Phase B as Red, and C as Orange (yip, resistor colour codes 1, 2, & 3).
Some will argue and claim that the cables need to be marked '1', '2', & '3'. Well, using the above chap's example, there are plenty of marked sleeves in the colours mentioned; slip-on, clip on, and heatshrink types. Best of both worlds!
Steering totally clear of using Black as Neutral - even though it is quiet rebellion, I reckon less deaths is a good reason to follow this route.