I'm not an expert in that standard, but at first glance it looks to me like it makes a distinction between handles that are held or actuated in normal use vs handles that are *continuously* held in the hand in normal use. Similar to distinction made for surface temp limits in standards like 60950.
On Wed, Apr 5, 2023 at 6:52 AM Ken Javor <ken.ja...@emccompliance.com> wrote: > I may be missing something but the way I read it they provide you with two > different approaches to reducing the hazard of electric shock. One is > protective earth grounding, and the other is double insulation, or double > electrically isolated. These are mutually exclusive, being two different > approaches to achieving the same goal. > > Ken Javor > Phone: (256) 650-5261 > > > ------------------------------ > *From: *"Grasso, Charles" <charles.gra...@dish.com> > *Reply-To: *"Grasso, Charles" <charles.gra...@dish.com> > *Date: *Wed, 5 Apr 2023 07:41:02 -0600 > *To: *<EMC-PSTC@LISTSERV.IEEE.ORG> > *Subject: *Re: [PSES] Safety: 60335-1 conflicting clauses question - > earthing (or not) of handles > > 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 <http://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 <http://he...@unit3compliance.co.uk> > <mailto:he...@unit3compliance.co.uk <he...@unit3compliance.co.uk>> or call > 01274 911747. 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