I hope they do better with the Missile Defense Project at Fort Greely, Alaska. If they engineered a tunnel that leaks, I wonder if the Missiles will hit another missile? Oh well, they aren't the only one's. Fluor oversaw the construction of the Valdez Marine Terminal on the Trans-Alaska Pipeline in 1975-76. They somehow forgot to make sure the tray cables had equipment grounding conductors in them or around them (they were in nonmetallic sheaths.) The entire terminal with all 14 miles of cable trays was a grounding disaster. The steel tray cable support system was used as an equipment ground. But oops, what happens when the cables leave the tray and go underground to get to the loads in buildings and outside buildings. Well, they put the cables in directly buried rigid conduit with no protective coating in concrete . The conduits were bonded to the tray at one end and at the equipment at the other end to serve as the grounding path. But after 14 years the conduits started rusting through and equipment grounds were being lost all over the place. Valdez is a very wet place! Considering that many areas are Class 1, Division 1 hazardous locations this was a real safety hazard. Also, consider that almost 20 per cent of the Nation's Oil was being loaded onto tankers from this terminal and you can see the concern. So how did Fluor fix this after the federal whistleblowers went to Congress in 1993. They engineered there way around the problem by jumpering all the conduits together at both ends so the rusted ones would be bonded to the conduits that had not rusted open yet. That is the way it is today. Oh yes, one State Electrical Inspector would not accept this fix so they run his ass off and replaced him with an in house appointed inspector. Believe me, I know. This is a true story.
"Gerald Newton3" wrote in message news:4192fb31$ snipped-for-privacy@news.acsalaska.net...
For those of you that might be reading this post, I will follow-up with some more tidbits, since I had the rare opportunity to have such a personal relationship with Alyeska Pipeline Service Company, Whistleblowers, and Fluor engineers. One of the defenses for allowing and entire cabling system to be installed without equipment grounding conductors in the cables was the fact the design for all voltages above 208V, such as 480/277 volts used high impedance grounding with ground fault alarms. This would limit the ground fault current to some low magnitude on the order of a few amperes above the charging current. This is fine until a second fault occurs on a different phase before the first fault is cleared. And the likelihood of this occurring is nil? Not quite. In the year 2001, apparently, Alyeska had cut the maintenance electricians so badly that there were not enough manpower to repair a ground fault for several months. This is particularly true when such a fault occurs the the winter. Valdez gets up to 20 feet of snow making it very difficult to find faults in outside runs of conduit and equipment in the winter. Such was the case in 2001. So during the summer the maintenance electricians were attempting to find a ground fault that had been left over from winter. During that summer a temporary installation was made by a contractor to supply power to for other subcontractors using parts of the same system. This was done by using the existing feeders to mixers on crude tanks. Somehow during the 20 years of maintenance someone had used varnished cambric to insulate some damaged wires on these feeders. Of course, with the high annual rainfall, these repairs were wet and varnished cambric is absolutely worthless when wet. As such, the cambric was in contact with a grounded metal object. Now when the maintenance crew started to troubleshoot the ground fault, they turned on the circuit having the ground fault. Now the varnished cambric repair was on a different phase so instead of seeing 277 volts to ground it saw 480 volts RMS or 1.4 times this for a peak voltage of 678 volts. The cambric broke down and smoked the repair job and no breakers tripped because the equipment grounding path back to the source was of too high an impedance. This led to a major investigation by Alyeska into the contractors workmanship that did the work using the cambric repaired wire for temporary power. This investigation was short and incomplete but did not address the real problem of NO EQUIPMENT GROUNDING CONDUCTORS IN THE CABLES because no one wanted to even mention the root cause of the problem, especially since Alyeska had spent about $400 million doing an upgrade project in 1993-94. And part of that was to repair the grounding problem at the Valdez terminal.
Fortunately, the 2002 Code contains a small but important change to prevent this in Section 250.4(B) (4) Path for Fault Current. Electrical equipment, wiring, and other electrically conductive material likely to become energized shall be installed in a manner that creates a permanent, low-impedance circuit from any point on the wiring system to the electrical supply source to facilitate the operation of overcurrent devices should a second fault occur on the wiring system. The earth shall not be used as the sole equipment grounding conductor or effective fault-current path. FPN No. 1: A second fault that occurs through the equipment enclosures and bonding is considered a ground fault. FPN No. 2: See Figure 250.4 for information on the organization of Article
250.
If this requirement had been in effect when the terminal was built, the justification of using a high impedance grounded sytem could not have been used to justify not having equipment grounding conductors in the cables. The clear solution to this error is to replace the cables.
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