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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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