I recalled that this subject had been discussed in depth at a BSI committee meeting, but had to dig back to 1995 to find it. The BSI committee stated, in response to any enquiry such as yours : - ---------------------------------------------------------------------------- --- Please be aware that the third amendment to IEC 950 explains that Tables 1 and 2 are informative, the requirements being contained within the text of 2.7.1. and 2.7.4. Incorporating fuses in both the phase and neutral conductors remains an option and you may prefer to design your products using this approach. We have learned that, in practice, there are many items in circulation in Europe which incorporate only single pole fusing. Furthermore, the NOTE in 2.7.4 says that the examples are not necessarily valid for protective devices in the building installation. Where single pole fusing is adopted for Class 1 equipment to be installed in countries without a polarised supply connection, then 2 alternative construction practices which you may like to consider are : - 1. provide double insulation between both the phase and neutral and Protective Earth; or 2. Ensure that both the Protective Earth and un-fused conductor are capable of carrying the maximum fault current available from the building wiring. This information is provided in good faith and without liability. ---------------------------------------------------------------------------- --
I have noted that at least one manufacturer of fused inlet/filters, Schaffner, I think, have stated in their adverts for such double fused inlet connectors, that double pole fusing IS a requirement of IEC 950. I wrote complaining about this (as I tend to do), but I can't recall any response. We use single pole fusing in our products, though I note that the monitors we buy from an Italian supplier, certified by VDE, have double pole fusing. Regards. John Crabb, Development Excellence (Product Safety) , NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2 3XX E-Mail :john.cr...@scotland.ncr.com Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. VoicePlus 6-341-2289. --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
