Generally, in order to develope the full tensil strength of the bolt, it should be engaged by a minimum of 5 threads. Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 <http://www.berkeleysolar.com/> www.berkeleysolar.com
_____ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of North Texas Renewable Energy Inc Sent: Thursday, April 21, 2011 2:28 PM To: RE Wrenches Subject: [RE-wrenches] METAL ROOF ATTACHMENT Wrenches I'm proposing a PV array on a metal building with L feet attached directly thru the roof into the purlins. The plan is to use thread cutting SS bolts, a minimum of ¼-28 pitch. The metal is 14 ga and will engage over 2 full threads and because the array is only 2 landscape modules on NS rails there will be 2 bolts for every module. 36 total. Im using a mag base drill press so the144 holes will be straight & round. What surprises can I expect or is there an easier way to go about this. Your 2¢ is welcome. Jim Duncan North Texas Renewable Energy 486 W.N. Woody Road Azle Texas 76020 NABCEP Certified Solar PV Installer No.031310-57 TECL 27398 <mailto:nt...@1scom.net> nt...@1scom.net 817.917.0527 <http://www.ntrei.com/> www.ntrei.com
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