Hi Ray. You wrote:
<My question is: are twist on type connectors allowed for this type of equipment in Europe? Is there any standard or guide lines that I could refer to? Most standards that I have reviewed, only state that the connection must be reliable. So if there is an IEC standard for twist on connectors, and these connectors meet that standard, would not they be considered reliable?> These are the ceramic internal corkscrews, right? My answer would be that I would not design with these, and I would not recommend anybody use them. I've seen them used all over the world in various forms and I've never seen them fail, but then I've seen wooden houses, Ford Model 'T's and antique clocks all working perfectly, doesn't mean they are the best way to go. Crimped connections done with a proper tool are absolutely repeatable, and infallible. My dog could do a good crimped joint if I put the tool in his mouth. Twist on connectors joints are just too variable in quality, depending on grip strength, oily fingers, thickness of strands, anneal state of the copper, how much wire has been stripped, etc. etc. To meet IEC1010 the tracking and air distances would have to be better than minimum, something not predictable with twist-on's, particularly if they are subject to some pull, when they unwind a bit. If I told a Law Court or Insurance Company that we used these things to save a few cents, there would be a hushed silence before they pulled the lever. Why stop there? Why not use cotton wound insulated wire, or Vulcanised India Rubber mains cables, they were great in their time, but modern materials and methods have made them obsolete, not failures, but obsolete. In the States I saw a chap throw away the DIN standard 40 amp terminal blocks we provided in a motor casing, and wind the feed and motor winding tails round a bolt which had a washer and nut run on, tightened, then wrapped in PVC tape. The chap explained that 'He couldn't be doing with the terminals, he wanted the two wires to actually touch'. To my ultimate shame I couldn't think of anything to say. Just a few not-so-humble self opinionated cents worth... :-) Chris Dupres Surrey, UK.
