I think people are missing the core differences (pun intended). I lived in the UK for a while, and I believe the UK has stranded wires (easier to pull through conduit), whereas North America (I now live in Canada) has solid copper core wires. Twisting the solid core wires creates a significantly strong mechanical join, which is contained, enhanced, and insulated by the cap. Multi-strand wire when twisted does not provide as good a mechanical joint, and the cap is not easy to apply. Multi-strand wire is better anchored with a screw-down, not a twist. This is where I believe the motivation for the differences arise. Rolf Howard Winter wrote: >Dave, > >On Mon, 08 Aug 2005 13:26:16 -0400, Dave Tweed wrote: > > > >>...< >>We're actually a step ahead of you, then, because we (NEC) don't allow >>inaccessible joins at all. >> >> > >I didn't realise we were in a race! :-) > >The techniques and regulations are vastly different between here and there, maybe due to historical reasons. >It seems that the main emphasis there is on preventing fires, whereas here preventing people getting current >through them seems more important. Possibly the voltage differences account for some of that, but who knows? >For example we aren't allowed to have sockets in a bathroom, except for special "shaver sockets" that need a >different type of plug, are low-current only, with an isolation transformer built in. Consequently when my >girlfriend is here, she has to dry her hair in the bedroom, because hairdryers in bathrooms are a no-no! :-) > >It may be that some differences are due to different construction methods (most houses here are brickwork with >wet-applied plaster over it, rather than studwork and boarding over there) but what would you do if you had a >socket which you wanted to move in a direction away from the cable run, so needing a longer cable? That's the >only situation I have encountered where an inaccessible join was necessary. As I said, there is much >discussion as to whether, for example, under a floorboard is accessible or not! :-) > > > >>Wirenuts are not just a "cap" over a twisted join. The metal thread forms >>a high-quality gastight connection with the wires. When properly applied, >>they are at least as good as crimps and screw terminals, if not better. >>In fact, if you've got more than one wire to attach to the same terminal >>of an accessory, it's actually preferred if you use a wirenut to join the >>wires, including a short pigtail that goes to the accessory. >> >> > >Right, but the problem with that is that you end up with a lot of cable and nuts to "lose" behind the fitting, >which may not be that easy. Our wall-boxes are much more shallow than yours - 25mm is common, again probably >because of construction methods, and the accessories are designed to take multiple wires, either by having >large sized terminals (on sockets and switches) or blocks with several smaller ones (in ceiling roses). I >can't find any really good photos of the rear of sockets, but page 2 of this .PDF: >http://www.mkelectric.co.uk/PDF/technical/LOGIC_PLUS_tech.pdf does show an example slightly!. This is a >typical ceiling rose designed for what's known as "loop-in" wiring: >http://www.tlc-direct.co.uk/Images/Products/size_3/AACR.JPG As you can see, there would not be space in there >to get four wirenuts and cables (that's Neutral, Live, Earth, Switched Live) - the way it's wired is: >Earths all go into the single terminal away from the rest. >Neutral in, out and to the lamp go in one of the three-way blocks. >Live in, out and to the switch go into the other three-way block. >Switched Live from the switch and to the lamp go in the two-way block. >Loop-in wiring isn't the only way lighting is wired, but it's by far the most common these days. > > > >>Seriously, if you're going to do wiring over here, you'd be well-advised >>to become familiar with the National Electric Code, upon which nearly all >>state and local codes are based, if you don't want to create unnecessary >>grief for your GF down the road. It's published by the National Fire >>Protection Association (http://www.nfpa.org/). >> >> > >I'm not really "doing wiring" - the most I've done is to replace 2-pin with 3-pin sockets in situ, making sure >to get Al-compatible ones, since her house is wired in aluminium. During whatever copper shortage it was, we >went for having reduced-size earthing conductors and ring-main wiring to save copper, whereas over there they >seem to have gone for using Al instead. > >Incidentally, we don't have any "local codes" - the Wiring Regulations (16th Edition) applies across England >and Wales (not sure if it applies in Scotland - they are doing their own thing at the moment) but the move is >to harmonise with Europe, and there is talk that any standard in any country of the European Union be accepted >in any other, but there is some resistance since a lot has been established with one set of rules in mind, and >mixing them may result in dangerous situations falling between the cracks... > >Cheers, > > >Howard Winter >St.Albans, England > > > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist