From owner-freebsd-questions@FreeBSD.ORG Thu Oct 17 12:15:06 2013 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id E59F7EB2 for ; Thu, 17 Oct 2013 12:15:06 +0000 (UTC) (envelope-from frank2@fjl.co.uk) Received: from bs1.fjl.org.uk (bs1.fjl.org.uk [84.45.41.196]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 6B9612A73 for ; Thu, 17 Oct 2013 12:15:06 +0000 (UTC) Received: from [192.168.1.35] (host86-163-34-162.range86-163.btcentralplus.com [86.163.34.162]) (authenticated bits=0) by bs1.fjl.org.uk (8.14.4/8.14.4) with ESMTP id r9HCF3bs065362 (version=TLSv1/SSLv3 cipher=DHE-DSS-CAMELLIA256-SHA bits=256 verify=NO) for ; Thu, 17 Oct 2013 13:15:04 +0100 (BST) (envelope-from frank2@fjl.co.uk) Message-ID: <525FD4C8.1090600@fjl.co.uk> Date: Thu, 17 Oct 2013 13:15:04 +0100 From: Frank Leonhardt User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: freebsd-questions@freebsd.org Subject: Re: UPS buying suggestion References: <525F0138.1020304@fjl.co.uk> <20131017093820.6a8428de@X220.ovitrap.com> <1381988697.5852.16.camel@archlinux> <20131017142910.61325830@X220.ovitrap.com> <1381992680.5852.45.camel@archlinux> In-Reply-To: <1381992680.5852.45.camel@archlinux> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.14 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 Oct 2013 12:15:07 -0000 On 17/10/2013 07:51, Ralf Mardorf wrote: > On Thu, 2013-10-17 at 14:29 +0800, Erich Dollansky wrote: >> Industry is much worse. Their machines made early computers fail when >> the bigger machines started work. > I worked for an audio company. The audio workshops were rented rooms on > a farm, and the boss missed to check the values of the RCCB, which > nearly killed a friend. Bigger machines are a PITA ;). The RCCB had a > value that high, that it was dangerous to life for an audio workshop. A > big machine not only pollutes the mains, if you turn it on, it also will > "eat" the complete power and lots of it going in, doesn't come out. A > "normal" RCCB would turn off immediately. > > Most RCCB (aka ELCB, RCD) work (hereabouts anyway) work with counter-wound coils on the input and output of the supply such that he magnetic field is neutral if the current is the same. If it goes out of balance, it trips the switch. Normally 30mA difference is the rule. They don't have a value, as such. I heard that only 10mA is needed to interrupt your heart, but I've also heard 100mA. They're all potentially dangerous. It depends on the route taken by the current passes through your body - you'd have to try quite hard to get even 10mA in the wrong place, but I guess you could do it with rubber shoes and grasping the mains one your one hand and an earth spike with the other. I was taught to keep my left hand in my pocket when poking around stuff that might be live, and do it quite subconsciously.