On Saturday, October 08, 2011 08:01:44 PM andy pugh did opine: > On 8 October 2011 22:08, gene heskett <[email protected]> wrote: > > And there weren't any wire nuts in sight, just twisted > > together and taped. > > I am amazed that you guys use wire nuts, they look so gimcrack > compared the the screw clamps that are mandatory here. > (This is a typical UK wiring junction box) > http://www.tlc-direct.co.uk/Images/Products/size_3/AAJB5.JPG
Yikes! Perhaps marginally useful with stranded wire, but cold flow after 6 mo to a year would have me laying awake nights unless your locale has flat outlawed alu wire. Even with copper, I would want to re-tighten them at 3 to 5 year intervals because cold flow will eventually reduce the pressure that maintains the 'gas tightness' of the joint, allowing air/oxygen to enter and oxidize the connection, potentially starting a fire. alu wire will do it in a year, copper 20-40, but it _will_ eventually happen. With alu, it has happened to me! Fortunately, our bedroom was where the service box was in a closet 8 feet from the bed, with the meter head on the outside of the house. With a 6ga alu jumper between the meter head and the bus in the 60 amp box. We had about 5kw worth of electric heaters running at the time. I recognized the sound of an intermittent arc in my sleep, opened the service box door and I could see the light coming in from the meter head. Got dressed (it was about -15 outside, 2AM), went out and cut the seal on the meter head ($25k fine & 6 months in Nebraska for that!), tossed it in the snow, pulled another 1/4" of wire and reconnected it. Put the meter back in and called Ron at Wayne Co Public power and told him what I'd done, and if he would be so kind as to drop by in about 2 days, I'd have that alu crap replaced with real copper & _then_ he could re-seal it. I could get away with that stuff where Joe Lunchbucket wouldn't since I was the engineer in charge of their biggest customer, KXNE-TV, whose hourly power draw was about 225 KWH, 18.5 hours a day. While there are some ultra cheap wire nuts out there that do not have the tapered coil "square wire" spring in the socket, with the square arranged so the sharp inner edge bites into the wire, while at the same time expanding slightly as the wires enter deeper into the taper, most do, and they can remain tight due to the spring tension under some pretty bad vibration and temp extremes if properly tightened. To that end, Scotch has added side wings to the insulator cap, and good electricians carry a couple pieces of plastic pipe with cuts in the end to fit over those wings so they can tighten them properly without blistering fingers and thumbs when doing them for a whole day. That wire nut may look poor to you, but quality ones represent a long life, gas tight joint because the square spring wire bites into the conductor with quite high pressure, and its a spring, so it can maintain that pressure till it rusts away if the weather can get to it. They are however, supposed to be inside, and inside a wiring box, usually about 2"x2"x3.5". In-wall, the box can be plastic, but exposed should be steel. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) One meets his destiny often on the road he takes to avoid it. ------------------------------------------------------------------------------ All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2dcopy2 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
