On Wed, 5 Apr 2023 11:23:03 +0100, "James Pawson (U3C)" <ja...@unit3compliance.co.uk> wrote:
> 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. ... > 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. ... > 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 I don't know of the reason of the differences, but it appears clause 22.35 (including the last paragraph "For stationary appliances...") is for constructions, and clause 22.36 is for entier appliances. Regards, Tom On Wed, 5 Apr 2023 11:23:03 +0100, "James Pawson (U3C)" <ja...@unit3compliance.co.uk> wrote: > 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 > <mailto: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 > > <http://www.unit3compliance.co.uk> www.unit3compliance.co.uk | > <mailto:ja...@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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