The Earth colour is not G/Y because that throws up all kinds of moulding difficulties, and means a complex second set of expensive dies and a double (2 shot) moulding machine.

Some DIN rail earth terminals look like they've been single-shot moulded using a mix of yellow and green plastic - result is more of a smear of blotches rather than any kind of neat stripe and to my mind they look absolutely terrible - but presumably comply with standards.. Give me a plain colour and use symbol marking to identify the terminals any day.

   - Andy.

davezawadi (David Stone): 
 

The Earth colour is not G/Y because that throws up all kinds of moulding difficulties, and means a complex second set of expensive dies and a double (2 shot) moulding machine. It doesn't matter does it and this is not cable insulation so out of scope for BS7671?

It's not out of scope for BS EN 60445 though, which in this case aligns with BS 7671 … 

I am much more concerned that wires are not tightly fixed as I said above.

Agreed, that is concerning. I've not seen this with properly fitted screwless connectors I've used … but I've not had hands-on with this particular product.

You need to study creep somewhat Graham, it is not a normal temperature phenomenon in copper, only perhaps if the wire gets very hot (hundreds of degrees), and usually work hardening will limit any small change due to the screw pressure (which is very high hopefully). 

I'm happy with experience which tells me, better than trying to break down the particular element of theory in play, that screw terminals for copper conductors need tightening after a few years, regardless of whether they were tightened properly in the first place. Yes, copper has a much better resistance to creep than aluminium, but I know it still happens. It might not actually be “creep” proper, but other mechanical stresses coming to play all at the same time, and the fact that the copper is not evenly stressed - I say that because properly made crimp connections seem to fare far better.

AJJewsbury: 
 

The Earth colour is not G/Y because that throws up all kinds of moulding difficulties, and means a complex second set of expensive dies and a double (2 shot) moulding machine.

Some DIN rail earth terminals look like they've been single-shot moulded using a mix of yellow and green plastic - result is more of a smear of blotches rather than any kind of neat stripe and to my mind they look absolutely terrible - but presumably comply with standards.. Give me a plain colour and use symbol marking to identify the terminals any day.

   - Andy.

plain yellow would be permissible on this premise in BS 7671, but not in BS EN 60445.

What BS EN 60445 actually says is “The single colours GREEN and YELLOW are only permitted where confusion with the colouring of the conductors in accordance with 6.3.2 to 6.3.6 is not likely to occur.” 

Which is another way of saying what BS 7671 says regarding green alone.

In this case, there is clearly confusion as green is used for the function.

Colours may be applied to terminals or conductors for identification according to BS EN 60445 (Table A.1 of that standard).

I perfectly agree that the earth terminal is marked with the graphical symbol  for protective conductor, but the terminal is also identified incorrectly as “E” not “PE” on some products: BS 1363-2 only specifies the graphical symbol, so I don't know where “E” comes from.

(OK you could loop one of the c.p.c.s through the back box terminal if you're using reduced size c.p.c.s. (e.g. T&E) - but it's a bit messy and probably isn't going to work with full sized c.p.c.s. as most many back box terminals won't take more than one larger conductor).

Is the earth terminal in the metal back box a BS 1363 accessory or junction box to BS EN 60670-22?

If not, should the use of it as part of a ring final circuit be recorded under 133.5 even when looped?

Regards

BOD

Well in terms of green and yellow,  you could use a marbeling screw prior to injection - it is what wago do for their DIN rail terminals, but the results are not stripes,  more of a badly mixed paint appearance.

 But there is no problem here, the coloured levers are neither terminals nor  insulation they could just as easily be black or pink for all 3 groups …  And even if it wasn't might be cheaper to lobby the BSI to change the standards to match the product, than to redesign it  significantly. That seems to work for AFDDs.

Mike.