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Joined: Feb 2002
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Paul,
Just a question to satisfy my curiosity. I was cruising the TLC website and I wondered if their prices are reasonable by your standards? Are they the "trade counter" price or are they marked up considerably. I know the mail order places in the US tend to be a rip-off.
Also, as you probably know, electricians get a discount from the wholesalers here.
Peter
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Joined: Oct 2002
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Bjarney, The outer sheathing of the SWA cable referred to in your link is PVC. SWA cables should be terminated in brass cable glands that grip the wire armouring, & an earth tag which enables a crimp lug with earth wire to be attached. We are still permitted to use the wire armouring as a circuit protective conductor (EGC in US terminology) in most circumstances. However it is increasingly common for 3 core cables to be used instead of 2 core in single phase circuits to provide a copper cpc/earth wire in addition to the wire armouring.
Trumpy, I would like to see our T&E cables changed to incorperate an insulated earth core, but it's true they are bare. Incidentally, we have been required to insulate & identify bare earth cores at terminations since the mid to late 1960's. Originally plain green sleeving or tape was used, after Dec 1977 green & yellow was the only colour acceptable for identifying earth wires. Green & yellow sleeving is widely available, & at less than £4 for 100M it is not expensive.
Paul, I don't understand your dislike for the adoption of g/y as the colour for earth wires. We both know it was done for sound safety reasons, colour blind people. A striped conductor stands out to all. Whoever came up with the idea of g/y as the international code for earthing cables was a genius. One day even the US will adopt it.
I understand what you are saying about some cables only having a thin stripe(s) of green on a yellow base. G/Y cables are supposed to have not less than 30% of either colour, & not more than 70% of the other colour, if you understand what I am trying to say. I only use British made, BASEC approved, branded (AEI, Pirelli etc.) cables & these are usually fine, but I have noticed some earth sleeving appears to be more than 70% yellow. Either way it still has 1 or more green stripes, making it apparent that the conductor is for earthing.
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Peter, TLC isn't too bad compared to some mail order prices, probably on a par with a lot of the "Big Orange" type stores, although there's often a lot of variation between different products so it's hard to be specific. They're certainly not as cheap as the big wholesaler that I generally use: BDC Electrical . The latter often has extra deals on discount cable etc. which is handy. They're also strictly trade-only, whereas TLC will sell to anyone. David, I've never been entirely convinced about the colorblindness argument. Sure, I can see how having just one-striped conductor out of three (or more) makes it easy to identify no matter what, but was it really necessary? I was always under the impreession that the most common form of color-blindness is the inability to distinguish red from green, and that bnth colors would appear the same to an afflicted person. If someone saw two wires which appeared to be the same color, wouldn't he go and ask for some help? I can't help wondering just how much trouble the old red/black/green system actually caused to colorblind people trying to wire a plug prior to 1970. Probably not half as much confusion as was caused to the numerous people who were totally lost by the introduction of brown and blue at the same time.
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Paul, I've just waded and driven through 2-3foot of snow to come up with an answer to your Colour-Blindness question!. Yes, another Fault Call-out, to repair a 3-phase Lathe, that kept on blowing HRC fuses. R-class, they were and there was a dead short to earth. Got my Avo-Megger on the case and found that there was a transposed Phase and Neutral, caused by the use of the Blue wire as a Neutral, in a Delta(mesh) connected system(it was hooked into a 3-pole MCB at the supplying board), I only found this because of the low reading to Earth, hooked it up the right way and he was turning like never before! Turning Brass of all things!, but who am I to argue!. . One of the easiest Faults calls I've done in a wee while, if you discount the snow!!!. And if you're wondering why I mentioned two lots of Circuit Protection, that's because it was hooked up that way!!!!. [This message has been edited by Trumpy (edited 07-05-2003).]
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I'm not quite following what had been done here. Was it a blue phase which had been erroneously connected to the neutral by someone following the "flex" code?
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Sorry Paul, At the time of posting that message, I was in a bit of a panic here, as the roof timbers were creaking and carrying on, with the weight of all the snow on it. What resulted, was I only told some of the story,here's the rest!. What had happened was, the owner of the Lathe, had hooked it up himself and he thought that with having a Blue wire, a Yellow wire and a Red wire at the lathe, as well as the Earth wire(Green), that he would hook up the Red and Yellow wires as per normal(he still had an empty B terminal, when I turned up). The Blue wire(that he thought was a Neutral) was joined to the frame of the Lathe, with the Earth wire, when I asked why this was so, he replied, "because it's like that at the switch-board".(Older MEN switchboards, here used to have the Main Neutral and Earth solder lugs on the same stud on the Neutral Busbar, along with the Range Neutral) Must have gone off, with a big bang!. Regarding the fusing, the HRC's fed the MCB and then to the Lathe sub-circuit, which also had no isolator. I have since been back to fix all of this up, it's fed via HD Flex and a chemical-proof isolator(because of the cutting fluid).
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That just goes to illustrate the perils of the British/Commonwealth systems usiung blue as both phase C and neutral in different circumstances. Maybe those who don't really know what they're doing shouldn't be messing around with the wiring, but we all know that they're going to anyway..... I think that when the standardized European colors were being agreed upon that the committees should have chosen something other than blue for neutral, and preferably a "neutral" color such as black, white, or gray. Looking at ECN's compiled list of colors then in cmmon use, I think I might have voted for gray. Black was neutral in the UK and Ireland, but a phase most everywhere else, so that's out. White was used as neutral in some places, but had only just been taken out of British regs. as an acceptable phase color a few years earlier. Gray was already in use as neutral in several countries and appears to have not been used as a phase elsewhere at that time.
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Paul, It would be a GOOD idea, if the WHOLE world, just moved to ONE single standard wiring colour, but I can't see that ever happening.
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It would be a GOOD idea, if the WHOLE world, just moved to ONE single standard wiring colour, but I can't see that ever happening. I think the best option is to just leave the color codes alone. "If it ain't broke......." It's unthinkable to mess with the color codes here in the U.S. Most people have enough trouble with the one we use allready!!
Peter
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At one time [>40 years ago] there was a similar problem with reversed phase and equipment ground in some North-American systems. Type-SO flexible supply cord is furnished with black, red, white and green insulated conductors. Before the grounding conductor was universally green, {if you can imagine back in the stone age} some used white for equipment grounding. Of course the problems were the same as in Trumpy's lathe case.
[This message has been edited by Bjarney (edited 07-08-2003).]
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