DC Positive - Red
DC Negative - Black
DC middle wire - Blue
This is the
new system in Ireland?
How come you still have red in there?
The old system for D.C. here (since 1966) is:
Positive "outer" = red
Negative "outer" = blue
Middle wire = black
The association of blue with D.C. negative has been around for a long time across fields well outside the IEE's scope, e.g. the distribution equipment for the traction supply on the London Underground (neither pole solidly grounded) is coded red=positive, blue=negative, and blue has long been used as the identifying color for -50V busbars in telephone exchanges.
Under the new system the IEE lists the following (Mike, you'd better get yourself a drink and sit down before you read this!):
Positive = brown
Negative = gray
Middle = blue
For a 2-wire circuit, the grounded conductor should be blue with brown or gray as appropriate for positive or negative "hot" line. If neither pole is grounded, then brown & gray should be used for positive & negative respectively.
http://www.iee.org/Publish/WireRegs/IEE_Harmonized_colours.pdfI recall discussing it in another thread.
