Date: Thu, 17 Oct 2013 13:15:04 +0100 From: Frank Leonhardt <frank2@fjl.co.uk> To: freebsd-questions@freebsd.org Subject: Re: UPS buying suggestion Message-ID: <525FD4C8.1090600@fjl.co.uk> In-Reply-To: <1381992680.5852.45.camel@archlinux> References: <CACo--msUpY-6r7MkuEvrPDpSVdFZyBotSA-eS7aLGMFDeq_vDQ@mail.gmail.com> <alpine.BSF.2.00.1310150911510.97788@wonkity.com> <CACo--mvUfcAy=0hyun21DZwSmdd=SmP7EeU-FVxJyiT_h4Rxkg@mail.gmail.com> <525F0138.1020304@fjl.co.uk> <20131017093820.6a8428de@X220.ovitrap.com> <alpine.BSF.2.00.1310162309200.14022@wonkity.com> <1381988697.5852.16.camel@archlinux> <20131017142910.61325830@X220.ovitrap.com> <1381992680.5852.45.camel@archlinux>
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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.
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