Ash and John, I seem to remember here in the US that even a lab technician can work on circuits that are external to the building 'mains' wiring. If the building 'mains' need modifications then an electrician is called in. Test labs (the actual test set up part) as stated fall into that gray area of not 'mains' wiring. Therefore, no issue with the actual wiring to the EUT. However, the exposed contacts in our test gear has bothered me somewhat over the years. I was told that our test gear is somewhat exempt from some NEC requirements because it is test gear, (ungrounded hipot comes to mind). This is where the specialist training comes into play for the lab / test technician.
Michael Sundstrom Electronic Lab Analyst, EMC Lead Overhead Door TREQ Center, Dallas [email protected] OFC: 214-579-6312 CELL: 940-390-3644 KB5UKT Philo Beddo <[email protected]> 07/30/2009 04:01 PM Please respond to Philo Beddo <[email protected]> To [email protected] cc Subject Re: [PSES] Workplace Safety Rules John, I work in the EH&S organization of my company. We've had to evaluate our lab's "Best Practices" against the OSHA requirements. In English, how we handle power and safety while performing EMC and safety testing. The biggest issue at hand was exposed connectors on LISN's and breakout boxes used for EMC and safety testing. This was many years ago, what we did was change nearly all the connections to "protected types". I'm not sure if there is an IEC number for them but Multi-contact makes safety connectors that fit nearly all current ratings. We modified LISN's, breakout boxes, and all test (banana) leads. That seem to satisfy the requirements. Ten years ago it cost us a bit less than $2000. When questions come up now, I point out that we don't ever have a situation where there is exposed live AC. I often worry that because we work with AC power from 120-480 that we'll get cited for not having a ceritified electrician on staff. On the other hand, I keep hoping for that so they'll get me certified and I don't have to worrry about all the wiring in my old farm house I've upgraded (to the NEC specs.) without having it inspected. I really think that a "best practice" document and training records documenting that all staff is trained in proper precautions and current the best practice document should fit the bill even for an over zealous plant manager. It's not a bad thing to have your lab audited for safety from time to time. The reality of EMC and Safety testing is that equipment may be ungrounded for brief moments during a leakage current test, that nearly all EMC testing is done over a ground plane with an prototype non-safety approved product, and in some cases the product may become unsafe as a result of the testing. But that is the nature of the job. Ash ________________________________ From: "Flavin, John" <[email protected]> To: [email protected] Sent: Thursday, July 30, 2009 1:56:02 PM Subject: Workplace Safety Rules I like to know this group's experiences regarding the following, which has been put into my lap to resolve. Our plant manager recently arranged a class on electrical safety (based on OSHA regulations and the NFPA 70E standard) for our engineering staff who work in all of our labs. The instructor was given a tour of our facility, including our Safety and EMI labs (due to the large size and power requirements of our products, we have our own safety and EMI labs. Safety testing is witnessed by a test engineer from an outside lab, which writes the CB reports for us; our EMI lab is NVLAP accreditted). During the course of the class, the instructor showed several "examples" of items taken from both these labs as possible items which were "unsafe". For example, he showed a power cord which had a section of the outer insulation stripped off, so that the individual insulated conductors were visible, and asked if this was safe. (How else do you put a current clamp around one conductor in a 3phase, 5 wire cord?). Our plant manager wanted to know why a 32A pin and sleeve connector with the appropriate HAR cordage (which we use when our product is sold in Europe) didn't have 6 gauge UL approved cordage. Adapters to allow us to connect our EUT to LISNs and CDNs for EMI testing likewise were suspect. There were other examples, but you get the idea. We're not talking about using wire nuts and duct tape to kludge together some AC cords to provide 50A service to our product. All these adapters have been built for a specific purpose, and use the appropriate sized conductors for the rated current of the plug/connector. The class also covered activities which can only be performed by a "qualified worker" (as defined by OSHA). Examples given were using a voltmeter to read AC line voltage, or replacing plugs/connectors on AC mains cords. As we test our products for both domestic (60Hz) and European (50Hz), we have two large synthetic power sources, and to avoid destroying very expensive racks of equipment, we routinely check the AC voltage before we plug in our products. Apparently, we are not qualified to do this. I understand our plant manager's concern that OSHA might cite some of these things as safety violations, which would cost us $$$ to rectify, and would probably shut down our lab from doing any work until we satisfy OSHA. His view is that it's not sufficient that these two labs are restricted access (all of us working in these labs have been issued numbered, "do not duplicate" keys), but that there must be detailed instructions for the use of every item, and for every type of measurement we make, and that any of this equipment should be locked away within these locked labs (which is a non-trivial issue for our EMI lab). He argued that these types of things are the proverbial "attractive nuisance", prone to abuse. My questions are 1) If an OSHA inspector were to visit an EMI or safety lab, would he be sufficiently knowledgeable as to what type of work is normally done there, or would he essentially "go by the book", and if it isn't in the NEC or NFPA, it's bad? Does anyone have any experience (good or bad) with this? 2) The thought of having to write, in excruciating detail, a procedure for every conceivable type of measurement we make, or could make hardly seems a productive use of my time, considering that the intended audience are already well versed in these practices, and that I couldn't possibly cover the universe of measurements we may do in the future. As part of our EMI lab training, we make a general statement that lab personnel shall be capable of using lab equipment such as voltmeters, current probes, oscilloscopes, spectrum analyzers etc. for debugging, which implies knowing how to use them to make appropriate measurements. Is this good enough? What level of detail is appropriate? What do other labs do to address this? John D. Flavin Teradata TCP Engineering 17095 Via del Campo San Diego, CA 92127 [email protected] V: (858) 485-3874 F: (213) 337-5432 - 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] <mailto:[email protected]> > All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc <http://www.ieeecommunities.org/emc-pstc> Graphics (in well-used formats), large files, etc. can be posted to that URL. 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