From owner-freebsd-hackers Fri Mar 6 19:16:24 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id TAA12882 for freebsd-hackers-outgoing; Fri, 6 Mar 1998 19:16:24 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from sendero.simon-shapiro.org (sendero-fddi.Simon-Shapiro.ORG [206.190.148.2]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id TAA12863 for ; Fri, 6 Mar 1998 19:16:00 -0800 (PST) (envelope-from shimon@sendero-fxp0.simon-shapiro.org) Received: (qmail 22618 invoked by uid 1000); 7 Mar 1998 03:24:16 -0000 Message-ID: X-Mailer: XFMail 1.3-alpha-021598 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: Date: Fri, 06 Mar 1998 19:24:16 -0800 (PST) Reply-To: shimon@simon-shapiro.org Organization: The Simon Shapiro Foundation From: Simon Shapiro To: Chuck Robey Subject: Re: SCSI Bus redundancy... Cc: lada@ws2301.gud.siemens.at, hackers@FreeBSD.ORG, julian@whistle.com, wilko@yedi.iaf.nl, dmlb@ragnet.demon.co.uk, Terry Lambert , Karl Denninger Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On 07-Mar-98 Chuck Robey wrote: > On Fri, 6 Mar 1998, Karl Denninger wrote: > >> On Fri, Mar 06, 1998 at 05:49:17PM -0800, Simon Shapiro wrote: >> > Telcos run equipment on 48VDC. In most switching rooms, not only you >> > are >> > not allowed (and do not have) power grid AC, you cannot even generate >> > it >> > inside your own cabinet. > > Unless it's changed in the last 5 years, that's not true. The telco's > test equipment is made by companies like HP, and runs on AC (not to > mention the technicians stereos!). Of course they have AC in their > office, and on every single equipment bay. My hardware people inform me that virtually all Telcos, domestic and international do not allow ANY AC equipment installed. I can belive test equipment is A/C, but test equipment is not permanently attached, rack-mounted. > Of course, their equipment does largely run on 48V nominal (which usually > means around 55-56 V in fact, else the battery plant'd not ever get > charged). Getting buzzed with 48V is nothing, even with 1500 Amps behind > it, I've been bitten countless times. Ringing battery is _much_ more > painful! Old style teletype, at polar +- 130V, would _really_ wake you > up (thank god that was interrupted). We used to run many painful practical jokes with these. I used to powe an old tube HiFi amplifier with a collection of these. BTW, some Telcos now allow A/C equipment in the rack, but not as part of their network. Network equipment must be DC, AFAIK. Simon Note: What has that got to do with FreeBSD? Quite a bit if you want to install a server in a switch... To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message