Hi James, Please find below some additional thoughts on the subject that have accidentally been discussed off-list.
Kind regards, Bernd Von: Dürrer Bernd Gesendet: Donnerstag, 6. April 2023 11:36 An: John Woodgate <j...@woodjohn.uk> Betreff: AW: AW: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles Agreed. The standard would be clearer if clauses 22.35 and 22.36 would start with "For class II constructions, [...]". However, I am neither a member of the national nor international committee for IEC 60335-1. Kind regards, Bernd Von: John Woodgate <j...@woodjohn.uk<mailto:j...@woodjohn.uk>> Gesendet: Donnerstag, 6. April 2023 11:14 An: Dürrer Bernd <bernd.duer...@wilo.com<mailto:bernd.duer...@wilo.com>> Betreff: Re: AW: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles [EXTERNAL E-MAIL] This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender. Noted, but the standard doesn't explicitly address that situation, which is surely very rare, and I understand that the handles could be reliably earthed. I still recommend the simple solution of covering them with reinforced insulation, but the standard needs to be clarified. ====================================================================================== Best wishes John Woodgate OOO-Own Opinions Only www.woodjohn.uk<http://www.woodjohn.uk/> Rayleigh, Essex UK I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi (340 - 245 BC) On 2023-04-06 10:00, Dürrer Bernd wrote: As I understand from James' explanations, the metal handles of the appliance in question are not reliably earthed. As such, these parts of the appliance do not comply with the requirements for a class I appliance (IEC 60335-1, 3.3.9) that all conductive accessible parts shall be connected to the protective earthing conductor in the fixed wiring of the installation. Therefore, these handles shall be assessed as class II construction (IEC 60335-1, 3.3.11 and 5.14) for which the requirements of clauses 22.35 and 22.36 are applicable. Kind regards, Bernd Von: John Woodgate <j...@woodjohn.uk><mailto:j...@woodjohn.uk> Gesendet: Donnerstag, 6. April 2023 10:46 An: Dürrer Bernd <bernd.duer...@wilo.com><mailto:bernd.duer...@wilo.com> Betreff: Re: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles [EXTERNAL E-MAIL] This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender. It still doesn't make sense to require double or reinforced insulation for a Class I product. Doing so, causes the safety of Class 1 construction to be questioned. ====================================================================================== Best wishes John Woodgate OOO-Own Opinions Only www.woodjohn.uk<http://www.woodjohn.uk/> Rayleigh, Essex UK I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi (340 - 245 BC) On 2023-04-06 09:40, Dürrer Bernd wrote: Hi James, actually, these two clauses address two different, but related risks: Clause 22.35 addresses the risk that the handle itself may become live. In any case, a conductive surface (like the handle) has to be separated from live parts by basic insulation. Due to the higher risk that handles are actually touched in the event of failure of basic insulation, the standard requires additional precautions. Either the handles itself shall be covered by insulating material (i.e. supplementary insulation) or they shall be separated by supplementary insulation from their fixing. In both cases, the handle will be protected by double insulation from live parts. Clause 22.36 addresses the risk that other parts than the handle in the vicinity of the handle may become live. Again, there is a higher risk for the user in the event of failure of basic insulation that these surfaces may be actually touched, so also for these neighbouring conductive surfaces either double or reinforced insulation is required. Kind regards, Bernd Von: James Pawson (U3C) <ja...@unit3compliance.co.uk><mailto:ja...@unit3compliance.co.uk> Gesendet: Mittwoch, 5. April 2023 12:23 An: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Betreff: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles [EXTERNAL E-MAIL] This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender. 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 1. Standard is IEC EN 60335-1:2012 (+amendments) 2. Context is an exercise machine (the appliance) 3. Supply is AC mains Class I 4. 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. 1. Class I appliance, with metal handles held during use so this requirement is applicable 2. Handles are not reliably earthed so we are advising manufacturer to make an explicit bond to PE 3. With Basic insulation and Earthing we have our two safeguards between live and user = reduced risk of shock 4. 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 1. This clause appears to not allow for earthing of the metal handles 2. Instead, only rouble or reinforced insulation are acceptable 3. Thoughts / speculation: * Would this clause make more sense if it read "For appliances other than those of class I..."? i.e. unearthed * 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. 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