Re: [PSES] Touch temperature limits for accessible parts

[Richard Nute]

 

Hi Scott:

 

A 1st degree skin burn occurs when skin temperature is 44 C.  Plastic material 
has relatively high thermal resistance.  80 C plastic is unlikely to cause a 
burn regardless of contact time.  In a separate message, I will send separately 
my paper on thermal injury from the 2014 ISPCE.  From this you can calculate 
whether or not a burn will occur.  

 

Stay safe, and best regards,

Rich

 

Ps:  A charger running at more than 80 C is poorly designed.   

 

 

From: Scott Xe  
Sent: Thursday, September 2, 2021 6:02 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Touch temperature limits for accessible parts

 

I am looking for advice on temp measurements and the requirements. I have an 
in-car charger with a temp of 80 degC on external plastic enclosure at max 
load.  Referring to EN 62368-1, the max temp is from 48 - 94 degC depending on 
the time to be touched to operate the equipment.  During operation, it is 
unnecessary to touch the external enclosure except plugging in and taking out 
from cigarette socket.  Is it deemed to apply 94 degC?

 

Should the max temp be measured at room temp of 25 degC or the maximum 
operating temp?  If at max operating temp, how to derive the max temp limits in 
such conditions?

 

Thanks and regards,

 

Scott


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Re: [PSES] [EXTERNAL] [PSES] Touch temperature limits for accessible parts

[Ted Eckert]

Hello Scott,

IEC 62368-1 clause 3.3.7.4 defines "normal operating condition" as the "mode of 
operation that represents as closely as possible the range of normal use that 
can be reasonably expected". It specifies the range of possible uses, not the 
"typical" use. Note 1 for the clause makes it clear that the most unfavorable 
default conditions must be considered for normal use.

If your charger is permanently connected to the device that it is charging, is 
it possible to load the device such that it continuously draws the maximum 
power from the charger? If the charger has a connector, allowing different 
loads to be connected, could the user charge a series of devices, one after the 
other, keeping the charger at maximum power for an extended time? "Normal" does 
not mean "likely" or "common". "Normal" is what is allowed and foreseeable.

In the United States, a number of mountain and southwestern states have freeway 
speed limits up to 80 miles per hour. The vast majority of cars in the United 
States will never travel at 80 mph for extended periods. If you did a survey, I 
would expect you to find that, on average, the typical American car spends less 
than 0.1% of the time at 80 mph. However, travelling continuously at that speed 
is allowed and possible, and a small subset of drivers will drive at that speed 
regularly. It's neither typical nor common, but it is "normal" and must be 
considered a normal condition.

Ted Eckert
The opinions expressed are my own and do not necessarily reflect those of my 
employer.

From: Scott Xe 
Sent: Thursday, September 2, 2021 8:02 AM
To: Ted Eckert 
Cc: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [EXTERNAL] [PSES] Touch temperature limits for accessible parts

Dear Ted,

Many thanks for your good considerations!  I need to re-assess this issue 
inclusive of those conditions.  I have one conflicted point about the touch 
temperature of 80 degC which is at full load.  As you may know it, the full 
load may happen at the initial charging and the charging current will gradually 
decrease.  In general, it may not be so hot in normal conditions.  What is your 
view on this?

Kindest regards,

Scott

On Thu, 2 Sept 2021 at 21:43, Ted Eckert 
mailto:ted.eck...@microsoft.com>> wrote:
Hello Scott,

Touch temperatures are measured at an ambient of 25 C. However, there are a 
number of additional considerations.

  *   What are normal operating conditions? Is it true that the user would 
never touch the charger while it is in operation? There is no chance that they 
would try to disconnected it from the car's socket while it is at maximum 
temperature?
  *   If the user could disconnect it, how long do they need to hold it to pull 
it out of the car's socket? Consider all users. For example, somebody with 
arthritis and a poor grip might need more time to disconnect the charger.
  *   Think about how TS2 limits apply to touch temperatures. What are the 
abnormal and fault conditions?
  *   Even if the standard would only require testing at 25 C, you need to 
consider that a car charger will be used at much higher ambient temperatures. 
Have you done a hazard analysis based on the specific use of this device?
  *   Will elevated temperatures on the charger result in customer complaints? 
If the charger gets very hot, will it be perceived as unsafe?

Ted Eckert
The opinions expressed are my own and do not necessarily reflect those of my 
employer, TC 108 or the Society of Automotive Engineers.

From: Scott Xe mailto:scott...@gmail.com>>
Sent: Thursday, September 2, 2021 6:02 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [EXTERNAL] [PSES] Touch temperature limits for accessible parts

I am looking for advice on temp measurements and the requirements. I have an 
in-car charger with a temp of 80 degC on external plastic enclosure at max 
load.  Referring to EN 62368-1, the max temp is from 48 - 94 degC depending on 
the time to be touched to operate the equipment.  During operation, it is 
unnecessary to touch the external enclosure except plugging in and taking out 
from cigarette socket.  Is it deemed to apply 94 degC?

Should the max temp be measured at room temp of 25 degC or the maximum 
operating temp?  If at max operating temp, how to derive the max temp limits in 
such conditions?

Thanks and regards,

Scott
-


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Re: [PSES] Touch temperature limits for accessible parts

[Scott Xe]

Dear Doug,

Thanks for your references!  I will try to obtain those references for
study.

Cheers!

Scott

On Thu, 2 Sept 2021 at 22:34, Doug Nix  wrote:

> Hey Scott,
>
> You might want to have a look at
>
> EN 563, Safety of Machinery—Temperatures of touchable surfaces—Ergonomics
> data to establish temp. limits
> EN 13202, ERGONOMICS OF THE THERMAL ENVIRONMENT - TEMPERATURES OF
> TOUCHABLE HOT SURFACES - GUIDANCE FOR ESTABLISHING SURFACE TEMPERATURE
> LIMIT VALUES IN PRODUCT STANDARDS WITH THE AID OF EN 563
>
> ISO 13732-1:2006, Ergonomics of the thermal environment — Methods for the
> assessment of human responses to contact with surfaces — Part 1: Hot
> surfaces
>
> Doug Nix
> d...@ieee.org
> +1 (519) 729-5704
>
> On 2-Sep-21, at 09:02, Scott Xe  wrote:
>
> I am looking for advice on temp measurements and the requirements. I have
> an in-car charger with a temp of 80 degC on external plastic enclosure at
> max load.  Referring to EN 62368-1, the max temp is from 48 - 94 degC
> depending on the time to be touched to operate the equipment.  During
> operation, it is unnecessary to touch the external enclosure except
> plugging in and taking out from cigarette socket.  Is it deemed to apply 94
> degC?
>
>
> Should the max temp be measured at room temp of 25 degC or the maximum
> operating temp?  If at max operating temp, how to derive the max temp
> limits in such conditions?
>
>
> Thanks and regards,
>
>
> Scott
> -
> 
>
> 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
>
> Attachments are not permitted but the IEEE PSES Online Communities site at
> http://product-compliance.oc.ieee.org/ can be used for graphics (in
> well-used formats), large files, etc.
>
> 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:
> Scott Douglas 
> Mike Cantwell 
>
> For policy questions, send mail to:
> Jim Bacher 
> David Heald 
>
>
>

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Jim Bacher:  
David Heald: 

Re: [PSES] [EXTERNAL] [PSES] Touch temperature limits for accessible parts

[Scott Xe]

Dear Ted,

Many thanks for your good considerations!  I need to re-assess this issue
inclusive of those conditions.  I have one conflicted point about the touch
temperature of 80 degC which is at full load.  As you may know it, the full
load may happen at the initial charging and the charging current will
gradually decrease.  In general, it may not be so hot in normal
conditions.  What is your view on this?

Kindest regards,

Scott

On Thu, 2 Sept 2021 at 21:43, Ted Eckert  wrote:

> Hello Scott,
>
>
>
> Touch temperatures are measured at an ambient of 25 C. However, there are
> a number of additional considerations.
>
>- What are normal operating conditions? Is it true that the user would
>never touch the charger while it is in operation? There is no chance that
>they would try to disconnected it from the car’s socket while it is at
>maximum temperature?
>- If the user could disconnect it, how long do they need to hold it to
>pull it out of the car’s socket? Consider all users. For example, somebody
>with arthritis and a poor grip might need more time to disconnect the
>charger.
>- Think about how TS2 limits apply to touch temperatures. What are the
>abnormal and fault conditions?
>- Even if the standard would only require testing at 25 C, you need to
>consider that a car charger will be used at much higher ambient
>temperatures. Have you done a hazard analysis based on the specific use of
>this device?
>- Will elevated temperatures on the charger result in customer
>complaints? If the charger gets very hot, will it be perceived as unsafe?
>
>
>
> Ted Eckert
>
> The opinions expressed are my own and do not necessarily reflect those of
> my employer, TC 108 or the Society of Automotive Engineers.
>
>
>
> *From:* Scott Xe 
> *Sent:* Thursday, September 2, 2021 6:02 AM
> *To:* EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* [EXTERNAL] [PSES] Touch temperature limits for accessible parts
>
>
>
> I am looking for advice on temp measurements and the requirements. I have
> an in-car charger with a temp of 80 degC on external plastic enclosure at
> max load.  Referring to EN 62368-1, the max temp is from 48 - 94 degC
> depending on the time to be touched to operate the equipment.  During
> operation, it is unnecessary to touch the external enclosure except
> plugging in and taking out from cigarette socket.  Is it deemed to apply 94
> degC?
>
>
>
> Should the max temp be measured at room temp of 25 degC or the maximum
> operating temp?  If at max operating temp, how to derive the max temp
> limits in such conditions?
>
>
>
> Thanks and regards,
>
>
>
> Scott
>
> -
> 
>
> 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
> 
>
> Attachments are not permitted but the IEEE PSES Online Communities site at
> http://product-compliance.oc.ieee.org/
> 
> can be used for graphics (in well-used formats), large files, etc.
>
> 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
> 

Re: [PSES] Touch temperature limits for accessible parts

[Doug Nix]

Hey Scott,

You might want to have a look at 

EN 563, Safety of Machinery—Temperatures of touchable surfaces—Ergonomics data 
to establish temp. limits
EN 13202, ERGONOMICS OF THE THERMAL ENVIRONMENT - TEMPERATURES OF TOUCHABLE HOT 
SURFACES - GUIDANCE FOR ESTABLISHING SURFACE TEMPERATURE LIMIT VALUES IN 
PRODUCT STANDARDS WITH THE AID OF EN 563

ISO 13732-1:2006, Ergonomics of the thermal environment — Methods for the 
assessment of human responses to contact with surfaces — Part 1: Hot surfaces

Doug Nix
d...@ieee.org
+1 (519) 729-5704

> On 2-Sep-21, at 09:02, Scott Xe  wrote:
> 
> I am looking for advice on temp measurements and the requirements. I have an 
> in-car charger with a temp of 80 degC on external plastic enclosure at max 
> load.  Referring to EN 62368-1, the max temp is from 48 - 94 degC depending 
> on the time to be touched to operate the equipment.  During operation, it is 
> unnecessary to touch the external enclosure except plugging in and taking out 
> from cigarette socket.  Is it deemed to apply 94 degC?
>  
> Should the max temp be measured at room temp of 25 degC or the maximum 
> operating temp?  If at max operating temp, how to derive the max temp limits 
> in such conditions?
>  
> Thanks and regards,
>  
> Scott
> -
> 
> 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 
> mailto:emc-p...@ieee.org>>
> 
> All emc-pstc postings are archived and searchable on the web at: 
> http://www.ieee-pses.org/emc-pstc.html 
> 
> Attachments are not permitted but the IEEE PSES Online Communities site at 
> http://product-compliance.oc.ieee.org/ 
>  can be used for graphics (in 
> well-used formats), large files, etc.
> 
> 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:
> Scott Douglas mailto:sdoug...@ieee.org>>
> Mike Cantwell mailto:mcantw...@ieee.org>>
> 
> For policy questions, send mail to:
> Jim Bacher mailto:j.bac...@ieee.org>>
> David Heald mailto:dhe...@gmail.com>>
> 


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Jim Bacher:  
David Heald: 

Re: [PSES] [EXTERNAL] [PSES] Touch temperature limits for accessible parts

[Ted Eckert]

Hello Scott,

Touch temperatures are measured at an ambient of 25 C. However, there are a 
number of additional considerations.

  *   What are normal operating conditions? Is it true that the user would 
never touch the charger while it is in operation? There is no chance that they 
would try to disconnected it from the car's socket while it is at maximum 
temperature?
  *   If the user could disconnect it, how long do they need to hold it to pull 
it out of the car's socket? Consider all users. For example, somebody with 
arthritis and a poor grip might need more time to disconnect the charger.
  *   Think about how TS2 limits apply to touch temperatures. What are the 
abnormal and fault conditions?
  *   Even if the standard would only require testing at 25 C, you need to 
consider that a car charger will be used at much higher ambient temperatures. 
Have you done a hazard analysis based on the specific use of this device?
  *   Will elevated temperatures on the charger result in customer complaints? 
If the charger gets very hot, will it be perceived as unsafe?

Ted Eckert
The opinions expressed are my own and do not necessarily reflect those of my 
employer, TC 108 or the Society of Automotive Engineers.

From: Scott Xe 
Sent: Thursday, September 2, 2021 6:02 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [EXTERNAL] [PSES] Touch temperature limits for accessible parts

I am looking for advice on temp measurements and the requirements. I have an 
in-car charger with a temp of 80 degC on external plastic enclosure at max 
load.  Referring to EN 62368-1, the max temp is from 48 - 94 degC depending on 
the time to be touched to operate the equipment.  During operation, it is 
unnecessary to touch the external enclosure except plugging in and taking out 
from cigarette socket.  Is it deemed to apply 94 degC?

Should the max temp be measured at room temp of 25 degC or the maximum 
operating temp?  If at max operating temp, how to derive the max temp limits in 
such conditions?

Thanks and regards,

Scott
-


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 
mailto:emc-p...@ieee.org>>

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Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/
 can be used for graphics (in well-used formats), large files, etc.

Website: 
http://www.ieee-pses.org/
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unsubscribe)
List rules: 
http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
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Mike Cantwell mailto:mcantw...@ieee.org>>

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-
-

[PSES] Touch temperature limits for accessible parts

[Scott Xe]

I am looking for advice on temp measurements and the requirements. I have
an in-car charger with a temp of 80 degC on external plastic enclosure at
max load.  Referring to EN 62368-1, the max temp is from 48 - 94 degC
depending on the time to be touched to operate the equipment.  During
operation, it is unnecessary to touch the external enclosure except
plugging in and taking out from cigarette socket.  Is it deemed to apply 94
degC?



Should the max temp be measured at room temp of 25 degC or the maximum
operating temp?  If at max operating temp, how to derive the max temp
limits in such conditions?



Thanks and regards,



Scott

-

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Website:  http://www.ieee-pses.org/
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List rules: http://www.ieee-pses.org/listrules.html

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David Heald: