What is a "NEC (National Electrical Code) inspector" ? In any case, the electrical/fire inspector should have noted specific NFPA70 clauses. You cannot conform to code until you know the requirement.
Fault conditions, as described for Type Tests in a product safety standard, are not defined in the NEC. The NEC 'tends' to describe required construction for various combinations of specific ratings and environments. The biggie is for > 150V to P.E., where all exposed metal must be 'grounded' for Class I construction. I do not like this, but there is an NEC clause that allows an exemption for insulated heat sinks. From: [email protected] [mailto:[email protected]]On Behalf Of Christine Rodham Sent: Wednesday, May 13, 2009 7:38 AM To: [email protected] Subject: Re:NRTL Mark vs. NEC Inspector List Members, We have an interesting problem. We sold an OEM product ( very high end Home Theater Movie Projector , better than a movie theater quality) which was listed by a well known NRTL. ( We modify and enhance the SW for high end performance) The projector was installed in a public place and the installation was evaluated by a NEC ( National Electrical Code ) inspector. The projector has a metal ungrounded heat sink attached to the chassis that was added for cooling but was evaluated and approved by the NRTL. The NEC inspector will not sign off on the installation stating non-current carrying exposed metal parts that may be accidentally energized must be grounded to the chassis. Grounding the heat-sink to the chassis will be difficult due to the design of this special aluminum heat-sink. Here are my questions: * What is the criteria to determine if a metal part can become accidentally energized? The only way it could happen in this case is if the power cord that is near the heat-sink is damaged and then touches the heat-sink. The power cord is UL approved and properly rated. * How many fault conditions ( single vs multiple ) are considered to determine if a metal part can become accidentally energized. * What would be our best option in arguing this ruling. Should we request another inspector or get the NRTL involved? Note that this unit is ceiling mounted and only trained service people would have access to it after the initial installation. Thank you! Christine Rodham - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
