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Joined: Oct 2000
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Paul, Sheesh! Sounds like a troubleshooter could have his hands full over there! It's enough to even make him drink warm beer! (kidding) Bill
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Hi Paul, First, I should point out that we don't have combined neutral/ground busbars here; the neutral is kept separate throughout a customer's installationThis, in itself, is the root of much ado here. This is facinating!
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Sparky, Where ya been Bub? Don't We have common Neutral/Grounding Busbar/Terminal Strip at a typical service? Bill
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Hi Bill.. been on vacation, mess machine is full of pleading and/or cursing customers. Don't We have common Neutral/Grounding Busbar/Terminal Strip at a typical service? yes we do, and all the problems that go along with it, which they ( in the UK) avoid. As I understand it, there have been some interesting aurguments, and even ROP's to apply thier system of N & G isolation starting at the X-former on in...
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Sparky, You seem to have told Pauluk that We didn't have this common connection. Originally posted by sparky: Hi Paul, First, I should point out that we don't have combined neutral/ground busbars here; the neutral is kept separate throughout a customer's installation
Bill
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Yes, the voltage-type ELCBs can certainly throw one a few curves. I just went to quote for a job this morning and saw one of these. I'll be advising the customer to let me replace it with the current-operated (i.e. GFI) type, but at a cost of 70 pounds (about $100) plus 17.5% tax I won't be surprised if he refuses.
Another problem with these devices crops up for radio enthusiasts such as myself. Because the house ground doesn't go directly to the ground rod but via the large inductance of the tripping coil, the house earth wiring can carry quite a lot of high-frequency noise, particularly now that computer equipment with its high leakage filters is so common.
Never mind that warm beer, just send me some of that nice American drink from the banks of the Mississippi..!
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Paul, 17.5% Tax? Whoa!! sounds like time for a 'Tea Party' if you know what I mean! Bill
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hmmm, I've messed up here! Paul, could you please review the N & G of your system and the ELCB application ?
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Originally posted by Bill Addiss: Paul, 17.5% Tax? Whoa!! sounds like time for a 'Tea Party' if you know what I mean! BillI know exactly what you mean, and I agree with you completely! The 17.5% VAT (sales tax) applies to almost everything, except a few exempt items such as food, books, children's clothes, etc.) And you really don't want to know how much we have to pay for gasoline.....
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Originally posted by sparky: hmmm, I've messed up here! Paul, could you please review the N & G of your system and the ELCB application ? It happens to the best of us. Re-reading the thread, it looks as though some quotes got attributed to the wrong person at one point. Let's try and straighten things out: In our main panels there are ALWAYS separate neutral and ground busbars/strips with no link between them. There are three distinct grounding methods still in use, depending upon the type of distribution network. 1. Armored underground feeds, found on older services in towns. The ground busbar is bonded to the armor of the supply cable, which in turn is grounded at the utility's xfmr. The incoming neutral goes ONLY to the neutral busbar, there is no N-to-G link on the customer's premises & no ground rod is needed. ELCBs were NOT fitted as standard. (Note: When installed, these town systems had the neutral grounded ONLY at the xfmr star-point.) 2. Overhead twin lines. Standard service for decades in rural areas. Again, incoming neutral goes ONLY to the neutral busbar and there is no N-G link. The house ground is provided by a local ground rod, and because of the resultant high loop impedance, an ELCB was/is almost always used. (As above, originally the only ground on the neutral was at the utility's xfmr.) 3. PME (Protective Multiple Earthing). Used since the 1930s in some rural areas, with overhead feeds. This is the only system with a N-G link at the house. The neutral & ground are still separate at the main panel, but instead of the main grounding lead running to cable armor or a gnd-rod, it is bonded to the incoming neutral AT THE SERVICE BLOCK. This is located before the meter, and is the only point of contact between N & G. No separate rod or ELCB is needed. (With PME the utility co. has ground rods on their neutral along its route at regular intervals.) When reading this, keep in mind that compared to U.S. residential service we tend to use a smaller quantity of larger xfmrs to feed a given number of homes. Since the 1980s, most of the LV distribution networks have been converted to allow PME operation, but many of the houses retain their original grounding method. Does this help, or have I made it worse?
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