I'm just replacing an old room stat with a new one. The old one is the
2-wire (plus CPC) version, and the new one is a Honeywell 3-wire (plus CPC). I have no problem with the actual wiring (cable is already run).However, is there any convention for which of the three colours is used for live, switched live, and neutral? My instinct would be brown for live, grey for switched live, and black for neutral....
Brown for line, black with brown sleeve for switched line and grey with blue sleeve for neutral.
Use of a black core for neutral is strongly deprecated since it is now a line (phase) colour.
Bloody hell, that was quick for this time of night...
I did wonder about the black, but was pretty sure about the brown...and yes, I do have brown and blue sleeving...
Thanks...will get on with that tomorrow.
Bob Eager coughed up some electrons that declared:
Perversely, I've heard of a lot of people (IET Forums) trying to avoid black for neutral to positively break the old association (eg 3 core SWA taking L/N/E to a shed).
I think that's taking things a bit far, but it's what I've heard.
Everyone seems agreed that the usual single phase line colour (ie brown) is a good candidate to use for the permanent live.
At the end of the day, as long as it's sleeved correctly to remove all ambiguity that's what matters most, but grandma, eggs etc... ;->
Cheers
Tim
On Thu, 28 May 2009 00:13:39 +0100, Andy Wade had this to say:
Isn't that totally crackers?
It's the sort of thing that could only be dreamed up by the EU.
On Thu, 28 May 2009 00:47:03 +0100 someone who may be Frank Erskine wrote this:-
Nice try, but it wasn't dreamed up by the EU. Neither is it crackers.
It was "dreamed up" by the IET. They gave members and interested people some time to cogitate on the matter. To make cogitation easier they provided a table of wiring colours in (IIRC) at least western Europe. I couldn't think of a better solution to the one they implemented, but if you can do so then why not suggest it to show that if only they had asked you they would have been amazed by you spotting something thousands of others didn't. By the way the main issue was not with black, that was a fairly easy one, but whether to retain separate colours for each phase and, if so, after brown and black what third colour to use. Grey was the best option for this third colour in my view.
David Hansen coughed up some electrons that declared:
In my view, they should have left it alone. Red, yellow and blue were not only fine, but visually very clear - far better IMHO than brown, grey and black.
Whilst I can see the merits of harmonised colours on appliance flex, as those are made and marketed across the world, I see few merits in EU harmonisation down to this level.
Just my 2p's worth.
Cheers
Tim
Nobody asked me :-(
These colours don't seem 'natural' to me. With the old colours red was the obvious live - red for danger, black the obvious neutral.
With the new colours they seem the wrong way around; electricity is 'blue' to me, brown is a drab nuetral colour.
The Medway Handyman coughed up some electrons that declared:
I agree completely. I really don't know what demon of stupidity made them think switching a perfectly good established system was a good idea :(
On Thu, 28 May 2009 08:54:09 +0100 someone who may be Tim S wrote this:-
It was explained at the time. Quite possibly the IET/IEE web site has copies of their reasoning should you wish to point out the flaws in it. "We don't like change" is not a particularly convincing flaw.
Start wiring purple.
The whole problem stems from the problematic re-use of blue & black. So we shouldn't have done this - there's hardly a shortage of other colours.
It's only not convincing to people who have to fill their day dreaming up schemes where it's change for changes sake...
On Thu, 28 May 2009 06:28:30 -0700 (PDT) someone who may be Andy Dingley wrote this:-
Blue was only used in three phase wiring. Anyway the harmonised blue is a light blue, not the deep blue of the L3 conductor insulation.
Black is a more difficult case. However, my recollection of the discussion is that it is used to indicate an energised conductor in several wiring schemes and thus it made sense to adopt it.
"We" did this in the interests of standardisation. My recollection of the discussion is that the "plenty of other colours" become fewer when one looks into it. It is most unlikely that people would adopt a brand new wiring colour scheme just because the IET devised it.
Does seem strange to me too - since most used blue for neutral on the old colours when using three phase wiring for this purpose.
But I can understand the reasoning behind it. It might make sense to have triple and earth available for this purpose where the colours weren't used for anything else. Or even three browns would make sense.
Snag is brown now denotes one of the phase colours - and triple and earth is three phase wiring.
Isn't brown the earth wire;-)?
Adam
Hasn't it always?
Well can be either single or three...
Yes - but with RYB, blue wasn't an old colour for neutral - unlike black is now. Do try and keep up. ;-)
Then why those colours - then as now?
Well, yes. Earth is brown, red for danger/live. Magnolia for neutral? Sorted! :-)
David Hansen coughed up some electrons that declared:
I don't need to read their reasoning to have an opinion David.
I've also not seen *anyone* on the IET's forum (ie the "users") who have had a good word for it. Some are neutral but I don;t recall a single person praising it as a radical improvement that is solving a problem that everyone's been grumbling about for years.
Coming up with a less crap domestic installation cable than T+E would rate higher on my personal list.
To me it appears an wholly unnecessary change from a perfectly well understood and clear system.
Then I didn't have some invisible body pressurising me to "harmonise" for the sake of it.
Having used some new triple + E, it's a bloody pain in dimly lit areas to discern the colours - no where near as clear as R/Y/B.
How can this possibly be classed as "progress"?
Cheers
Tim
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