The blind leading the colourblind...

My reader may not be aware that there are some changes in the offing for wiring colour codes in medium voltage electrical installations (i.e. 230v/415v stuff).

Once upon a time, red was nasty, green harmless and black mostly harmless. Yellow and blue could also be nasty as well, and particularly nasty in conjunction with each other and red. Flex cable was red, black green as well until EU harmonisation came along. Then, Red became brown, black became blue and green was also yellow in a stripy sort of way. The green became yellow-green in permanent wiring as well, but red and black stayed.

Now, the brown/blue/yellow-green is making it into permanent installations, but just to make it more complex, yellow becomes black and blue becomes grey. All clear? You can download a handy guide care of PLASA, the professional lighting & sound association.

Just in case you think it is change for changes sake, yellow often used to be white and a very long time ago it was green. So there...

Of course for someone with a background in telephony, the worst we had to worry about was 86v AC superimposed on -50v DC which could give a nasty rash if it resulted in the victim scraping their hand up the back of the jumper tags.

-50v DC might sound quite benign but it could melt spanners when available at several thousand amps...