Joe, You can use light blue anywhere you want to as long as its not for grounding or grounded conductors. I think that you are looking for an answer that states 504-80(c). This section is permissive and does not require the use of light blue. It is also a very poorly written section. Does, "and where no other conductors colored light blue", mean that if I choose to use light blue for intrinsically safe circuits, I can't use light blue anywhere else in the structure? Don(resqcapt19)
Well, well, well.... The trusty British 13-amp plug!
I was going to mention the shuttered sockets at some point, but it looks like you've beaten me to it! The shutters have been a feature of the outlets since they first appeared some 50 years ago. Shutters were also adopted on the older round-pin outlets as well.
Some of the latest sockets have adopted a different shutter mechanism which isn't operated from the earth pin. Instead, they rely on equal pressure at the live & neutral to open; pressure on just one leaves it firmly closed. Definitely trickier for inserting test probes!
The cord colors are those I mentiond some time ago. We adopted them for flex in 1970 as part of a European standard, but retained the old colors (red, black, green) for fixed cables. The green has since be changed to green/yellow for earth though.
The fuses at each plug provide good protection for individual appliances, but I'm afraid that many people don't understand their significance. A lot of folk always put in a 13A fuse "because it's a 13A plug." I don't see many with the fuse clips bridged with wire though.
Originally posted by sparky: All told, it looks like a safer arrangement to me, for say...daycare receptacles.
The fact that kids might poke things in outlets is the main point put forward in favor of the shutters. If you consider that our pins are much thicker than those on U.S. plugs, then the range of metal objects which could otherwise be inserted is much greater. The hot side is a full 240V to ground of course, so it would pack quite a jolt.
For several years now it's been possible to buy molded plastic blanks with plastic pins which fit into an outlet. I guess the theory is that kids would be slowed down even more by having to remove that first.
I understand that these blanks are now required to be fitted in unused outlets in certain places, including daycare. IEE Regs. are mandatory in many public buildings, but this rule isn't from the IEE.
Apparently it's from a new amendment to the Healh & Safety at Work Act or one of the other similar gestapo-like depts.