Re: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[James Pawson (U3C)]

Hello Bernd,

 

Thank you for the links to the additional material on the IEC website. I
didn’t realise there was such a wealth of material in the documents from the
subcommittees.

 

Also, thank you for taking the time to write a considered reply.

 

I understand your interpretation and the notes from the committee. Reliable
earthing of the handles appears to be the simplest way to comply with the
requirements of the standard. I will advise the customer appropriately.

 

Longer term I’m going to do some more reading of the outputs from TC 61, TC
66 and TC 108. Good to know about this useful resource -
https://www.iec.ch/technical-committees-and-subcommittees#tclist

 

All the best

James

 

 

From: Dürrer Bernd  
Sent: Wednesday, April 12, 2023 7:48 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question -
earthing (or not) of handles

 

Hello James,

 

Thank you for providing this additional information and the sketch. My
conclusion that the handles are a class II construction was based on your
statement in your original post that the handles are not “reliably earthed”.
As I understand now from your additional information they are not earthed by
a dedicated wiring to the protective earthing conductor, but incidentally
the measured resistance complies with the requirements of IEC 60335-1,
clause 27.5. Please remember that the protective earthing connection shall
be reliable over the whole lifetime of the appliance. Apart from wear and
grease build up that you already mentioned you should check whether the
parts providing the connection comply with clauses 27.4 (corrosion) and 28
(screws and connections).

 

With respect to the question whether the requirements of clauses 22.35 and
22.36 also apply to handles of a class I appliance that are reliably earthed
(and therefore are not a class II construction), I recommend to check the
decisions of TC 61 that are published at
<https://www.iec.ch/dyn/www/f?p=103:227:100193794009456FSP_ORG_ID,FSP_LA
NG_ID:1236,25> IEC - TC 61 Dashboard > Documents: Working Documents, Other
Documents, Supporting Documents: I have found decisions on the
interpretation of clause 22.35 in the archives “TC 61 Inquiries 2011 and
previous” (
<https://assets.iec.ch/public/tc61/2011%20and%20previous%20Inquiries.zip?202
3041235>
https://assets.iec.ch/public/tc61/2011%20and%20previous%20Inquiries.zip?2023
041235) and “TC 61 Inquiries 2015” (
<https://assets.iec.ch/public/tc61/2015%20Inquiries.zip?2023041235>
https://assets.iec.ch/public/tc61/2015%20Inquiries.zip?2023041235). It seems
that the committee’s view is that these clauses are applicable to class I
constructions. However, as defined in the second paragraph of clause 22.35,
stationary appliances are exempt if their handles are reliably earthed.

 

Kind regards,

 

Bernd

 

Von: James Pawson (U3C) < <mailto:ja...@unit3compliance.co.uk>
ja...@unit3compliance.co.uk> 
Gesendet: Dienstag, 11. April 2023 12:22
An:  <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> EMC-PSTC@LISTSERV.IEEE.ORG
Betreff: Re: [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. 



Thank you to everyone who has replied to this query so far, your thoughts
were very helpful in refining my thinking.

 

To give some further context (some of which I should have provided earlier)

 

1.  The appliance is stationary and of class I construction
2.  The handles are held continuously in normal operation
3.  For a basic overview of construction please see the attached sketch
(or this link
<https://www.unit3compliance.co.uk/wordpress/wp-content/uploads/2023/04/iec-
60335-clause-22.35-and-22.36-context.png>  if the email reflector eats the
attachment)
4.  Whilst the grips are foam, it is light/porous in nature (not good
enough for Supplementary insulation) and it would be very easy for the user
to hold the metal instead
5.  We made some earth bonding resistance measurements on the equipment.
The handles are not explicitly earthed (via a Protective Bonding Conductor)
but the contact to the metal frame through the bearings and shafts (not
shown on sketch) gives a resistance of approx. 40mR @ 25A even under motion
of all joints. We have not accounted for any wear, grease build up, etc)

 

My views:

 

a.  I agree with the below discussions - it feels like the standard
could benefit from a wording change for clause 22.35 and 22.36 with each
clause starting “For class II constructions, […]”
b.  The construction of the appliance, and lengths of wiring involved,
means that if the Basic insulation fails (see 60335-1 Class I definition
below) then there is a very low likelihood of the handles becoming live. The
wires will only contact the earthed frame instead. 

[PSES] AW: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[Dürrer Bernd]

In my understanding this is just an informative note to the decision of the 
international IEC committee that the national committee of Australia and New 
Zealand has modified clause 22.35 in their nationally adopted version of 
60335-1 (as can be seen on the Standards Australia website AS/NZS 60335.1:2020 
- Standards 
Australia<https://www.standards.org.au/standards-catalogue/sa-snz/electrotechnology/el-002/as-slash-nzs--60335-dot-1-colon-2020>,
 AS/NZS 60335-1 is a modified adoption of IEC 60335-1).

Von: Elliott Martinson 
Gesendet: Mittwoch, 12. April 2023 15:32
An: EMC-PSTC@LISTSERV.IEEE.ORG
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.
For Australia and New Zealand; which have a reliable earthing system; it was 
agreed at the EL-002 (TC61 national committee) meeting in Wellington, February 
2009 that 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.

Found this in the TC 61 inquiries 2011 and previous
Would it count as "separated from live parts by earthed metal"?

From: Dürrer Bernd mailto:bernd.duer...@wilo.com>>
Sent: Wednesday, April 12, 2023 1:48 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - 
earthing (or not) of handles

Hello James,

Thank you for providing this additional information and the sketch. My 
conclusion that the handles are a class II construction was based on your 
statement in your original post that the handles are not "reliably earthed". As 
I understand now from your additional information they are not earthed by a 
dedicated wiring to the protective earthing conductor, but incidentally the 
measured resistance complies with the requirements of IEC 60335-1, clause 27.5. 
Please remember that the protective earthing connection shall be reliable over 
the whole lifetime of the appliance. Apart from wear and grease build up that 
you already mentioned you should check whether the parts providing the 
connection comply with clauses 27.4 (corrosion) and 28 (screws and connections).

With respect to the question whether the requirements of clauses 22.35 and 
22.36 also apply to handles of a class I appliance that are reliably earthed 
(and therefore are not a class II construction), I recommend to check the 
decisions of TC 61 that are published at IEC - TC 61 Dashboard > Documents: 
Working Documents, Other Documents, Supporting 
Documents<https://www.iec.ch/dyn/www/f?p=103:227:100193794009456FSP_ORG_ID,FSP_LANG_ID:1236,25>:
 I have found decisions on the interpretation of clause 22.35 in the archives 
"TC 61 Inquiries 2011 and previous" 
(https://assets.iec.ch/public/tc61/2011%20and%20previous%20Inquiries.zip?2023041235)
 and "TC 61 Inquiries 2015" 
(https://assets.iec.ch/public/tc61/2015%20Inquiries.zip?2023041235). It seems 
that the committee's view is that these clauses are applicable to class I 
constructions. However, as defined in the second paragraph of clause 22.35, 
stationary appliances are exempt if their handles are reliably earthed.

Kind regards,

Bernd

Von: James Pawson (U3C) 
mailto:ja...@unit3compliance.co.uk>>
Gesendet: Dienstag, 11. April 2023 12:22
An: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Betreff: Re: [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.
Thank you to everyone who has replied to this query so far, your thoughts were 
very helpful in refining my thinking.

To give some further context (some of which I should have provided earlier)


  1.  The appliance is stationary and of class I construction
  2.  The handles are held continuously in normal operation
  3.  For a basic overview of construction please see the attached sketch (or 
this 
link<https://www.unit3compliance.co.uk/wordpress/wp-content/uploads/2023/04/iec-60335-clause-22.35-and-22.36-context.png>
 if the email reflector eats the attachment)
  4.  Whilst the grips are foam, it is light/porous in nature (not good enough 
for Supplementary insulation) and it would be very easy for the user to hold 
the metal instead
  5.  We made some earth bonding resistance measurements on the equipment. The 
handles are not explicitly earthed (via a Protective Bonding Conductor) but the 
contact to the metal frame through the bearings and shafts (not shown on 
sketch) gives a resistance of approx. 40mR @ 25A even under motio

Re: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[Elliott Martinson]

For Australia and New Zealand; which have a reliable earthing system; it was 
agreed at the EL-002 (TC61 national committee) meeting in Wellington, February 
2009 that 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.

Found this in the TC 61 inquiries 2011 and previous
Would it count as "separated from live parts by earthed metal"?

From: Dürrer Bernd 
Sent: Wednesday, April 12, 2023 1:48 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - 
earthing (or not) of handles

Hello James,

Thank you for providing this additional information and the sketch. My 
conclusion that the handles are a class II construction was based on your 
statement in your original post that the handles are not "reliably earthed". As 
I understand now from your additional information they are not earthed by a 
dedicated wiring to the protective earthing conductor, but incidentally the 
measured resistance complies with the requirements of IEC 60335-1, clause 27.5. 
Please remember that the protective earthing connection shall be reliable over 
the whole lifetime of the appliance. Apart from wear and grease build up that 
you already mentioned you should check whether the parts providing the 
connection comply with clauses 27.4 (corrosion) and 28 (screws and connections).

With respect to the question whether the requirements of clauses 22.35 and 
22.36 also apply to handles of a class I appliance that are reliably earthed 
(and therefore are not a class II construction), I recommend to check the 
decisions of TC 61 that are published at IEC - TC 61 Dashboard > Documents: 
Working Documents, Other Documents, Supporting 
Documents<https://www.iec.ch/dyn/www/f?p=103:227:100193794009456FSP_ORG_ID,FSP_LANG_ID:1236,25>:
 I have found decisions on the interpretation of clause 22.35 in the archives 
"TC 61 Inquiries 2011 and previous" 
(https://assets.iec.ch/public/tc61/2011%20and%20previous%20Inquiries.zip?2023041235)
 and "TC 61 Inquiries 2015" 
(https://assets.iec.ch/public/tc61/2015%20Inquiries.zip?2023041235). It seems 
that the committee's view is that these clauses are applicable to class I 
constructions. However, as defined in the second paragraph of clause 22.35, 
stationary appliances are exempt if their handles are reliably earthed.

Kind regards,

Bernd

Von: James Pawson (U3C) 
mailto:ja...@unit3compliance.co.uk>>
Gesendet: Dienstag, 11. April 2023 12:22
An: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Betreff: Re: [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.
Thank you to everyone who has replied to this query so far, your thoughts were 
very helpful in refining my thinking.

To give some further context (some of which I should have provided earlier)


  1.  The appliance is stationary and of class I construction
  2.  The handles are held continuously in normal operation
  3.  For a basic overview of construction please see the attached sketch (or 
this 
link<https://www.unit3compliance.co.uk/wordpress/wp-content/uploads/2023/04/iec-60335-clause-22.35-and-22.36-context.png>
 if the email reflector eats the attachment)
  4.  Whilst the grips are foam, it is light/porous in nature (not good enough 
for Supplementary insulation) and it would be very easy for the user to hold 
the metal instead
  5.  We made some earth bonding resistance measurements on the equipment. The 
handles are not explicitly earthed (via a Protective Bonding Conductor) but the 
contact to the metal frame through the bearings and shafts (not shown on 
sketch) gives a resistance of approx. 40mR @ 25A even under motion of all 
joints. We have not accounted for any wear, grease build up, etc)

My views:


  1.  I agree with the below discussions - it feels like the standard could 
benefit from a wording change for clause 22.35 and 22.36 with each clause 
starting "For class II constructions, [...]"
  2.  The construction of the appliance, and lengths of wiring involved, means 
that if the Basic insulation fails (see 60335-1 Class I definition below) then 
there is a very low likelihood of the handles becoming live. The wires will 
only contact the earthed frame instead. At the moment, I don't agree that the 
handles would form a class II construction as protection is still provided by 
Basic + Earthing (but I'm willing to be persuaded by a convincing argument)

3.3.9 class I appliance
(basic plus earthing) in such a way that conductive accessible parts cannot 
become live in the event of a failure of the basic insulation


  1.  T

[PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[Dürrer Bernd]

Hello James,

Thank you for providing this additional information and the sketch. My 
conclusion that the handles are a class II construction was based on your 
statement in your original post that the handles are not "reliably earthed". As 
I understand now from your additional information they are not earthed by a 
dedicated wiring to the protective earthing conductor, but incidentally the 
measured resistance complies with the requirements of IEC 60335-1, clause 27.5. 
Please remember that the protective earthing connection shall be reliable over 
the whole lifetime of the appliance. Apart from wear and grease build up that 
you already mentioned you should check whether the parts providing the 
connection comply with clauses 27.4 (corrosion) and 28 (screws and connections).

With respect to the question whether the requirements of clauses 22.35 and 
22.36 also apply to handles of a class I appliance that are reliably earthed 
(and therefore are not a class II construction), I recommend to check the 
decisions of TC 61 that are published at IEC - TC 61 Dashboard > Documents: 
Working Documents, Other Documents, Supporting 
Documents<https://www.iec.ch/dyn/www/f?p=103:227:100193794009456FSP_ORG_ID,FSP_LANG_ID:1236,25>:
 I have found decisions on the interpretation of clause 22.35 in the archives 
"TC 61 Inquiries 2011 and previous" 
(https://assets.iec.ch/public/tc61/2011%20and%20previous%20Inquiries.zip?2023041235)
 and "TC 61 Inquiries 2015" 
(https://assets.iec.ch/public/tc61/2015%20Inquiries.zip?2023041235). It seems 
that the committee's view is that these clauses are applicable to class I 
constructions. However, as defined in the second paragraph of clause 22.35, 
stationary appliances are exempt if their handles are reliably earthed.

Kind regards,

Bernd

Von: James Pawson (U3C) 
Gesendet: Dienstag, 11. April 2023 12:22
An: EMC-PSTC@LISTSERV.IEEE.ORG
Betreff: Re: [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.
Thank you to everyone who has replied to this query so far, your thoughts were 
very helpful in refining my thinking.

To give some further context (some of which I should have provided earlier)


  1.  The appliance is stationary and of class I construction
  2.  The handles are held continuously in normal operation
  3.  For a basic overview of construction please see the attached sketch (or 
this 
link<https://www.unit3compliance.co.uk/wordpress/wp-content/uploads/2023/04/iec-60335-clause-22.35-and-22.36-context.png>
 if the email reflector eats the attachment)
  4.  Whilst the grips are foam, it is light/porous in nature (not good enough 
for Supplementary insulation) and it would be very easy for the user to hold 
the metal instead
  5.  We made some earth bonding resistance measurements on the equipment. The 
handles are not explicitly earthed (via a Protective Bonding Conductor) but the 
contact to the metal frame through the bearings and shafts (not shown on 
sketch) gives a resistance of approx. 40mR @ 25A even under motion of all 
joints. We have not accounted for any wear, grease build up, etc)

My views:


  1.  I agree with the below discussions - it feels like the standard could 
benefit from a wording change for clause 22.35 and 22.36 with each clause 
starting "For class II constructions, [...]"
  2.  The construction of the appliance, and lengths of wiring involved, means 
that if the Basic insulation fails (see 60335-1 Class I definition below) then 
there is a very low likelihood of the handles becoming live. The wires will 
only contact the earthed frame instead. At the moment, I don't agree that the 
handles would form a class II construction as protection is still provided by 
Basic + Earthing (but I'm willing to be persuaded by a convincing argument)

3.3.9 class I appliance
(basic plus earthing) in such a way that conductive accessible parts cannot 
become live in the event of a failure of the basic insulation


  1.  The low resistance of the incidental bearing connection is further 
mitigation against having to explicitly earth the handles
  2.  If live wiring or basic insulated wiring is routed anywhere near the 
handles on different versions of the appliance then they will need an explicit 
earth connection
  3.  I'm sure the standards committee had a specific case in mind when they 
wrote these clauses, I just wish there was an explainer document like EN 
62368-2!


Again, with thanks.
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 upda

[PSES] WG: AW: [PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[Dürrer Bernd]

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 
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 mailto:j...@woodjohn.uk>>
Gesendet: Donnerstag, 6. April 2023 11:14
An: Dürrer Bernd 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 <mailto:j...@woodjohn.uk>
Gesendet: Donnerstag, 6. April 2023 10:46
An: Dürrer Bernd <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) 
<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.  A

[PSES] AW: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[Dürrer Bernd]

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) 
Gesendet: Mittwoch, 5. April 2023 12:23
An: 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

  *   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:

 *   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. 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<ma

Re: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[T.Sato]

On Wed, 5 Apr 2023 11:23:03 +0100,
  "James Pawson (U3C)"  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)"  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 

Re: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[Scott Aldous]

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 
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" 
> *Reply-To: *"Grasso, Charles" 
> *Date: *Wed, 5 Apr 2023 07:41:02 -0600
> *To: *
> *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

Re: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[Ken Javor]

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" 
Reply-To: "Grasso, Charles" 
Date: Wed, 5 Apr 2023 07:41:02 -0600
To: 
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)
 wrote:
>  This message originated outside of DISH and was sent by:
> ja...@unit3compliance.co.uk
> 
> 
> Hello experts,
>  
> In running through some safety checks on a customer¹s product I¹ve come across
> what appears to be a conflict between two clauses. This resulted in some head
> scratching! I¹m 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 ³reliably earthed²
> (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 ³For appliances other than
> those of class IŠ²? i.e. unearthed
> 
> o   Talks about ³appliances² (whole product) rather than ³constructions²
> (parts of appliance)
> 
>  
> Conclusion
> I¹m 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
> can¹t rationalise this with clause 22.36. As I say, I¹m sure I¹ve 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 customers¹ 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 <mailto: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 : 

Re: [PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[Chas Grasso]

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) 
wrote:

> * This message originated outside of DISH and was sent by:
> 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  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
> 
> | 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. 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/
> 
> 

[PSES] Safety: 60335-1 conflicting clauses question - earthing (or not) of handles

[James Pawson (U3C)]

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 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 |
 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

 


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