"Dave Plowman (News)" wrote in message
...
In article ,
Steve Walker wrote:
To be fair the change to colours for fixed wiring was a stupid one for
the UK. Blue is neutral in the current system and a live (3ph) under the
old, causing huge risk of confusion on industrial sites.

Those who don't understand wiring colours shouldn't be allowed near
electricity - let alone 3 phase.

You can know both wiring schemes, but in the heat of the moment you may get
confused when one colour changes its meaning from live to neutral; at least
with the change in the colours for single-phase wiring, red and black were
not reused for other purposes in the new colours, but instead totally new
colours brown and blue were used instead.


The new wiring colours could have been made a lot better: I'd go for

brown-and-red, brown-and-blue, brown-and-yellow for the three lives

blue for neutral


This would preserve the association between brown and live, while allowing
the three phases to be distinguished by the secondary colour that was used
before.

Using black and grey for two different phases is asking for trouble, if the
grey insulation goes a bit dark and the black fades a bit light. Our central
heating system was wired up with 3-phase cable between the timer and the
boiler, for some bizarre reason, and he'd used black and grey for "CH on"
and "HW on", and the two colours were virtually indistinguishable. When I
was replacing the timer with a Hive controller, I stuck labels on the wires
to make it clear which was which, but when I was removing the Hive
controller and replacing it with the old one, when we were about to move
house, the labels ripped off so I had to guess - wire it up and see whether
the radiators started to get hot when the CH button was pressed, or whether
it needed the HW button to achieve this. Inevitably I got it the wrong way
round and had to swap them round. I should have used a spot of tippex on one
of the wires, rather than little labels stuck on with sellotape ;-)