Well, heck, why didn't you say so in the first place? If you are talking about a workplace practice with a possible exposure, you go to OSHA, not UL, ANSI, etc.
29CFR 1910.303(g)(2)(i)"....live parts of electric equipment operating at 50 volts or more shall be guarded....." Note that it does not distinguish AC/DC. 29CFR1910.333(a)(1) "....Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electric burns or explosions due to electrical arcs. Keith Gershon [email protected] Electrical Safety Engineer -------------------------------------- List-Post: [email protected] Date: 7/12/96 10:10 AM To: Keith Gershon From: Bob Received: by ehssmtp.lbl.gov with SMTP;12 Jul 1996 10:09:27 +0100 Received: from lbl.gov (lbl.gov [128.3.254.23]) by ehssun.lbl.gov (8.6.12/G) with SMTP id KAA06566 for <[email protected]>; Fri, 12 Jul 1996 10:09:58 -0700 Received: from ruebert.ieee.org by lbl.gov (4.1/1.39) id AA22514; Fri, 12 Jul 96 10:09:53 PDT Received: (from daemon@localhost) by ruebert.ieee.org (8.7.5/8.7.3) id LAA14535 for emc-pstc-list; Fri, 12 Jul 1996 11:20:12 -0400 (EDT) Message-Id: <[email protected]> List-Post: [email protected] Date: Fri, 12 Jul 96 11:01:47 EDT From: Bob <[email protected]> To: [email protected] Cc: [email protected] Apparently-To: [email protected] Subject: RE: Why 42.4AC\ 60VDC Sender: [email protected] Precedence: bulk Reply-To: Bob <[email protected]> X-Resent-To: Multiple Recipients <[email protected]> X-Listname: emc-pstc X-List-Description: Product Safety Tech. Committee, EMC Society X-Info: Help requests to [email protected] X-Info: [Un]Subscribe requests to [email protected] X-Moderator-Address: [email protected] Hello again, I had previously asked for references to an alleged occupational requirement for a maximum touchable voltage of 24V and I thank you for your responses. I saw nothing concrete which gave legitimacy for a 24V limit. I found the references to the telephone company interesting. I have another somewhat related question. What is the reasoning for selecting 42.2V peak and 60Vdc as a limit? Does UL explain this anywhere? The reason for this line of questioning is that I am involved in a debate on an electrical safe work practices policy(working on energized equipment). The issue of applicability involves who is covered. Ideally everything should be de-energized before performing work, but that is not always the case. There are plenty of situations where that will not occur. So, the question is at what voltage should the policy kick in. Regards, Bob Brister Digital Equipment Corp.
