Return-Path: Received: from rly-dc05.mx.aol.com (rly-dc05.mail.aol.com [172.19.136.34]) by air-dc04.mail.aol.com (v123.4) with ESMTP id MAILINDC041-b2349e6f57d30; Thu, 16 Apr 2009 05:08:17 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dc05.mx.aol.com (v123.4) with ESMTP id MAILRELAYINDC057-b2349e6f57d30; Thu, 16 Apr 2009 05:08:16 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1LuNZK-0000yu-H6 for rs_out_1@blacksheep.org; Thu, 16 Apr 2009 10:07:38 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1LuNZK-0000yl-4E for rsgb_lf_group@blacksheep.org; Thu, 16 Apr 2009 10:07:38 +0100 Received: from mhost01h.leeds.ac.uk ([129.11.77.238]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1LuNZI-00024H-DK for rsgb_lf_group@blacksheep.org; Thu, 16 Apr 2009 10:07:38 +0100 Received: from APOLLO2.ds.leeds.ac.uk (apollo2.leeds.ac.uk [129.11.5.5]) by mhost01h.leeds.ac.uk (8.14.3/8.14.3) with ESMTP id n3G98j7P012755 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT) for ; Thu, 16 Apr 2009 10:09:17 +0100 (BST) Received: from HERMES8.ds.leeds.ac.uk ([fe80::7de0:fde9:3ffd:6b3]) by APOLLO2.ds.leeds.ac.uk ([129.11.5.5]) with mapi; Thu, 16 Apr 2009 10:07:18 +0100 From: Chris Trayner To: "rsgb_lf_group@blacksheep.org" Date: Thu, 16 Apr 2009 10:07:17 +0100 Thread-Topic: Arcs and sparks - user beware Thread-Index: Acm89bhbmRrsB2NgTQSNirFbfi+ydgBeovaZ Message-ID: <38F4A9873A5B474DB6FB337B1B69ABA10D7B925641@HERMES8.ds.leeds.ac.uk> References: In-Reply-To: Accept-Language: en-US, en-GB Content-Language: en-GB X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB MIME-Version: 1.0 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: LF: RE: Arcs and sparks - user beware Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=TO_ADDRESS_EQ_REAL autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) Dear Laurence, Thanks for your post. > (Its got a bit of MF in it honest)=20 Whether it has or not, it could save one of our lives some day! A friend who worked for the London Electricity Board years ago told me a sim= ilar story about working on 3-phase underground cables. You disconnect both=20= ends, then before you touch them you short each phase to earth. Rarely will=20= you have happened to disconnect at the zero-volts part of the cycle, so appa= rently you get some satisfying bangs. But that may not completely explain your recent experience. One would guess=20= that (a) you turned off the Tx before unplugging the aerial and (b) the Tx h= as a DC path across the aerial socket (e.g a transfo secondary). So did some= other process charge up your cable? Your experience might suggest that, for those who fiddle with their aerials=20= frequently, it might be worth permanently fitting a resistor (100k, say) acr= oss the two halves; or two, one from each pole to earth. 73, Chris G4OKW