How exactly does one measure "likely" as in likely to touch? Is it a %age? Of course my question is tongue in cheek...
On Wed, Apr 5, 2023, 4:23 AM James Pawson (U3C) <ja...@unit3compliance.co.uk> wrote: > * This message originated outside of DISH and was sent by: > ja...@unit3compliance.co.uk <ja...@unit3compliance.co.uk> * > ------------------------------ > > Hello experts, > > > > In running through some safety checks on a customer’s product I’ve come > across what appears to be a conflict between two clauses. This resulted in > some head scratching! I’m sure it is my misunderstanding or misreading, but > I could do with some pointers in how to unpick this. > > > > *Context* > > - Standard is IEC EN 60335-1:2012 (+amendments) > - Context is an exercise machine (the appliance) > - Supply is AC mains Class I > - Appliance has metal handles that are held during normal use. These > are connected through bearings to the metal frame but are not “reliably > earthed” (no explicit wired connection) > > > > *Earthing of metal parts is acceptable* > > *22.35 For constructions other than those of class III, handles, levers > and knobs that are held or actuated in normal use shall not become live in > the event of a failure of basic insulation. If these handles, levers and > knobs are of metal and if their shafts or fixings are likely to become live > in the event of a failure of basic insulation, they shall be adequately > covered by insulating material or their accessible parts shall be separated > from their shafts or fixings by supplementary insulation.* > > > > *For stationary appliances and cordless appliances, this requirement does > not apply to handles, levers and knobs, other than those of electrical > components, provided that they are reliably connected to an earthing > terminal or earthing contact or separated from live parts by earthed metal.* > > > > - Class I appliance, with metal handles held during use so this > requirement is applicable > - Handles are not reliably earthed so we are advising manufacturer to > make an explicit bond to PE > - With Basic insulation and Earthing we have our two safeguards > between live and user = reduced risk of shock > - No complaints with this clause > > > > *Earthing of metal parts is not accpetable* > > Then the next clause seems to contradict this: > > > > *22.36 For appliances other than those of class III, handles which are > continuously held in the hand in normal use shall be constructed so that > when gripped in normal use, the operator's hand is not likely to touch > metal parts unless they are separated from live parts by double insulation > or reinforced insulation* > > > > - This clause appears to *not* allow for earthing of the metal handles > - Instead, only rouble or reinforced insulation are acceptable > - Thoughts / speculation: > > o Would this clause make more sense if it read “For appliances other > than those of class I…”? i.e. unearthed > > o Talks about “appliances” (whole product) rather than “constructions” > (parts of appliance) > > > > *Conclusion* > > I’m happy that the approach of reliably earthing the metal handles will > reduce the electric shock risk in the context of the equipment, this > approach being consistent with other safety standards I know like 62368-1 > and 61010-1. I just can’t rationalise this with clause 22.36. As I say, I’m > sure I’ve misread or misunderstood something so any help would be greatly > appreciated. > > > > Otherwise, if anyone has a link to an explanatory document or contact for > someone who could help at standards or committee level again that would > help. > > > > All the best > > James > > > > James Pawson > > Managing Director & EMC Problem Solver > > > > *Office hours:* > > *My mornings are reserved for full attention on consultancy, testing, and > troubleshooting activities for our customers’ projects. I am otherwise > contactable between 1300h to 1730h from Monday to Friday.* > > *For inquiries, bookings, and testing updates please send us an email on > he...@unit3compliance.co.uk <he...@unit3compliance.co.uk> or call 01274 > 911747. Our lead times for testing and consultancy are typically 4-5 weeks.* > > > > *Unit 3 Compliance Ltd* > > *EMC : Environmental & Vibration : Electrical Safety : CE & UKCA : > Consultancy* > > > > www.unit3compliance.co.uk > <http://www.unit3compliance.co.uk> > | ja...@unit3compliance.co.uk > > +44(0)1274 911747 | +44(0)7811 139957 > > 2 Wellington Business Park, New Lane, Bradford, BD4 8AL > > Registered in England and Wales # 10574298 > > > - > ---------------------------------------------------------------- > > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. 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To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1