1415 75TH ST SW CONTOUR AEROSPACE 2018-01-02 MF Import

C NTOUR INDUSTRIES 23 October 1996 City of Everett Inspection Department 3200 Cedar St. Everett, WA 98201 At(ention: Tim Alaniz Dear Tint, We are writing this letter in regard to ground fault interruption (GFI) requirements for the 480 volt three phase electrical service to he installed at 1415 75th Street S.W., Everett, WA. Mr. Lome Wallitner from Rodgers Electric is designing the electrical installation for this location and, after design approval, will be responsible for the installation of all necessary equipment and wiring. As part of the design process, Lome has discussed with us the possible problems and potential hazards that might be engendered by use of GFI. As we understand the situation, with GFI enabled, a ground fault condition will cause a complete shutoff of electrical power to all equipment connected to the affected service disconnect. In our cr se, we have 3 service disconnects with ratings of 2.500 amps, 2,000 amps, and 1,600 amps. If our understanding is correct, use of GFI will definitely create a potential for personnel hazards and significant production losses. The machines to be installed in this building are designed for milling large structural parts for aerospace use and most of them are controlled by computers. If a power outage occurs during operation, these machines will come to a very abrupt uncontrolled halt. This tvpe of stoppage causes cutter miscuts, :hereby scrapping workpieces, and also causes excessive cutter loads, resulting in breakage of milling cutters. The materials being machined are very expensive, with unit prices ranging from $1,500.00 to as high as $20,000.00 each. A typical power outage might min six pieces of material with a total value well in excess of $18,000.00, not counting our investment in machining time and labor. As you can see, a very significant sum. In addition, although severe injury rarely results, the cutter breakage associated with a power outage does present a level of risk to our machine operators. From the foregoing, it would appear to be in our best interest to make the new electrical installation without incorporating GFI and we ask that you consider this letter a request for authorization to do so. If you should require additional information, or clarification of any data provided, please contact the undersigned or Mr. Lome Wallitner at your convenience. SSii'nncccerreelllyy Yours Del Convis Engineering Manager 2916 tooth St. SW, Unit A, Everett, WA 98204-1474 9 (206) 355-0616 • Fax: (206) 355.7360