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Joined: Jul 2002
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Just a small note, there are the odd gruesome references to injuries in this site. Only in text though, discretion is advised.
[This message has been edited by Trumpy (edited 02-14-2004).]
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Joined: Aug 2001
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Some interesting reports there. The contracts manager contacted the network owner to find out if electrical services were in the area where they were digging, and a verbal reply from his office was that there were no cables. The following day work began on digging holes and on the third hole an air hammer struck an 11,000 volt cable.
Once again the contractor failed to obtain clear assurance that the area was safe to work. A written confirmation would provide suitable evidence that inquiries were made, but I would place the blame with the network employee who apparently told the colntractor that the area was clear without bothering to check properly. A 15 year old youth received serious burns when he made contact with live parts on a berm mounted 11kV oil switch unit. It would appear that the busbar extension end cover had been removed previously by unauthorised persons. The youth was removing the heat shrink cover from one of the busbars when a flashover occurred. In order to ensure better protection from such vandalism of electrical equipment in the public environment, the use of anti tamper type fixing screws on covers needs to be considered It's sad to think that vandal-proof fixings are now necessary in such cases. What part of "Danger - High voltage" did he not understand?
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Joined: Jul 2002
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The sad part about all of this Paul, is I was driving past the Xformer down the road from my place (the one that Faulted a few months back) to find a Fencing Contractor driving a pick into the concrete to break it up. I told him to be careful as there were 33kV cables leading up into the Xformer. He asked me where they were, I checked my cable location diagrams and sprayed the area with neon paint. I came back later, no Contractor, but a failed 33kv feeder and a pick right through my paint mark. In hind-sight, after digging up the cable, the pick was welded to the cable. This is the junction of 6 33kV cables. There was a piece of hardened rock next to the pick though!.
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Joined: Jul 2002
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Just want to relate this to you people. Upon a Faults call tonight, as part of sectionalising a block of 4 roads, I had an ABS(Air-Break Switch) explode and rain down on me. Had I not been wearing my Fire Service bunker coat and Helmet+ visor at the time, I'd be in hospital now. These ABS's are made for dropping loads and can also be closed on load too. This must be one of the faulty batch that were made in the late 1980's, along with the Oil-filled Earth switches, that fire hot oil at you, if you shut them too quickly!.
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Joined: Apr 2002
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Trumpy’s advice is well heeded. A healthy respect for >600-volt gear is always warranted. [As is for <600V gear, too.] There is a phenomenal amount of heat and acoustic-shock energy in electric arcs.
You may not be directly involved with operating >600V distribution equipment, but it still is good to have some understanding of its capabilities in a malfunction. [One source of deadly accidents has been tradesman not identifying higher-voltage equipment, as NOT being 600V-class gear…like attempting to apply a (<1 kV) Simpson or Triplett multimeter to live 15kV-class circuits.]
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Joined: Jul 2002
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Bjarney, Interesting that you should mention Test Equipment with HV. Just how are circuits of different voltage identified in the US?. As in different wire colours? Or is it a case of "you don't know until you test"?. I am thinking that you can't put Warning Signs everywhere.
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Joined: Aug 2001
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Mike, I'm not sure about HV, but on low-voltage where both 120/208 and 277/480V systems are present in a building, different color coding is used to identify them, typically:
Black/red/blue + white neutral for 120/208 Brown/orange/yellow + gray neutral for 277/480
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Joined: Apr 2002
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We must learn to read {large AND small} equipment labels, and treat equipment as live and at a higher voltage until unambiguously determined otherwise. The basic concepts of “OSHA” 29CFR1910.331-335 must be applied.
We’ve all heard it many times—don’t forget that you are responsible for your own safety, but also we should never compromise the safety of our fellow workmates.
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