Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!gatech!bloom-beacon!husc6!cca!mirror!datacube!dje From: dje@datacube.UUCP Newsgroups: sci.electronics Subject: Re: Lightning Rod Problem Message-ID: <100500015@datacube> Date: Thu, 9-Jul-87 13:41:00 EDT Article-I.D.: datacube.100500015 Posted: Thu Jul 9 13:41:00 1987 Date-Received: Sun, 12-Jul-87 11:33:44 EDT References: <204600003@prism> Lines: 29 Nf-ID: #R:prism:204600003:datacube:100500015:000:1279 Nf-From: datacube.UUCP!dje Jul 9 13:41:00 1987 I understand that this rule applies: A direct lightening strike will be drawn to a thing only if the lightening was going to hit within a cone defined by the thing's top and a circle on the ground whose radius was that thing's height. That only counts for direct strikes. The Electric fields near the lightening get very high. I was unfortunate to be out on Mass Bay in an INTENSE lightening storm in a sailboat (40' mast) with ungrounded rigging. No direct hit, but I saw giant bolts hit 100 feet away. I recieved shocks from wet ropes and saw a 2" discharge from my hand to boat hardware. New underware was in order. I agree that lightening rods dissipate the field from nearby lightening, and I think they prevent damage from direct strikes. All masts should be grounded at *least* to a metal keel. If you get caught out in the water and you wonder if you're grounded, shackle a length of chain from a stay or shroud and let it drag in the water. Then stay away from everything. Dave Erickson ---------------------------------------------- ------ Datacube Inc. / /| 4 Dearborn Rd. ------ | Peabody, Ma 01960 || \| | ihnp4!datacube!dje || /|/ Human:(617)535-6644 ------ Fax: (617)535-5643