I've worked for Duke energy in Greensboro N.C.and yes we set mostly 45 class 4 or 5 poles and 50 class poles almost all the time. And yes they were strict about joint spacing and wanted at least 40 inches from neutral if you were any closer to neutral they will raise hell. However such tall poles are required since they have an 8 foot clearance between neutral and primary. Which means the spacing from the cross arm braces where they meet and not the actual distance between lines. http://www.ncdot.org/doh/preconstruct/traffic/itss/ws/manual/tms1.pdf
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