ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Harmonized Cables -- Arrived!

Yep, that just goes to show how much misinformation is floating around out there.

I still think this is one area where we should have put our foot down and just said "No, we will not be changing."

This change has far more to do with politics than with any genuine technical reason.

In Austria the book says this: Blue is only to be used as a neutral and all neutrals have to be blue. y/g is ground only. Only exception to the rule: grey (as in NYM-J 4x1,5) can be sleeved blue as a neutral. After the changes suppliers ran out of blue heatshrink tube.
Phases can be about any color except blue, y-g, yellow and green (not sure about the two latter, might be just Germany). The Germans just switched back to grey neutrals when using such cable

What I can't figure out is why blue came to be adopted as neutral in the first place.

It was clearly already established standard in some European countries by the 1960s, but does anyone know exactly where and when the use of blue neutrals originated?

If we had to change colors to a common standard, wouldn't gray have been a better choice anyway? Germanic countries were already used to gray being neutral and it wouldn't have clashed with existing British usage of blue as a phase. Were any other countries using gray as anything but a neutral 30-40 years ago?

Would have to dig up the age old thread about the old color codes, but I think there were definitely some countries that used grey as a phase.
All countries around here used dark blue as a phase too! Depending on whether it was a four- or five-wire system you had: black, red blue or black blue black for the phases. Possible combinations were: 4 wire TN-C: L1 black, L2 red, L3 blue, PEN grey. 4wire TT/TN-S: L1 black, L2 blue, L3 black, PE red. 5wire: like 4wire TT/TN-S but with a grey neutral.

The problem with the old color coding was the fact that the colors weren't sepcific. Red could be ground, PEN and phase, grey could be N or PEN, black could be about everything. With three or four way switches every color could become about anything. If conduit was used people didn't care at all as long as PEs if existant were red, but not even that was always the case (seen black and brown ones too in Germany).

Paul,
As I was always taught, the use of a Blue Neutral, came from the flex colouring.
In that, people with colour-blindness are less likely to get the Brown-Blue colours mixed up, as opposed to the old Red-Black.
People that are colour-blind usually cannot distinguish between Red and Black for same reason.
This colouring started with flexes because of consumers transposing the P-N wires on appliance plugs.
Just as a note, this colour coding thing sounds like a right nightmare.
People,(especially Electricians) will have to be doubly vigilant when working on electrical systems in a few years down the track.
With regard to sleeving wires, I don't personally like the idea of doing this, but then again, in existing installations, there is usually little choice, the thing that worries me the most when working on domestic systems, is where wires are sleeved in the middle of a run, 1 circuit I worked on a few years back, had 3 different coding changes along it's length, where new bits had been added over the years.

The colour blind problem is between red and green which under the old 'British' system was potentially fatal.

Doesn't explain where the blue came from though - maybe for a colour-blind person it makes it the most discrimiating trio of wires?

I too was always led to beleive that the inability to distinguish between red and green was the most common form of color blindness.

Obviously with red as phase and green as earth a transposition could be disastrous, but I've often wondered whether this has been over-emphasized. Maybe I've misinterpreted something, but I was under the impression that people suffering from red-green color blindness saw the two colors as being the same. If that's the case, then surely they wouldn't just guess at which is which?

If we're talking about electricians here probably not, but DIYers _would_! Most definitely!