A very nice clarification; thanks Rich.

As a case in point, I know of a least one high school in this jurisdiction 
where students (instructed persons) are allowed to assemble and test circuits 
consisting of magnitude 3 energy sources.  I wonder if the school board needs 
to review that practice, since the principles of electric circuits can be 
taught just as effectively using magnitude 1 energy sources.

Ralph McDiarmid
Product Compliance
Solar Business
Schneider Electric

-----Original Message-----
From: Richard Nute [mailto:ri...@ieee.org] 
Sent: Thursday, November 09, 2017 1:04 PM
To: Ralph McDiarmid <ralph.mcdiar...@schneider-electric.com>; 
Subject: "persons" in IEC 62368-1

In IEC 62368-1, three different persons are defined with respect to their 
knowledge of safety, not with respect to other parameters.

An "ordinary person" is naïve with regard to the safety of the equipment.  
Therefore, an "ordinary person" must have the full protections specified in the 
standard.  "Ordinary person" is defined in the IEC Glossary, 


A "skilled person" is an expert with regard to the safety of the equipment.  He 
is "expected to use their training and experience to recognize energy sources 
capable of causing pain or injury and to take action for protection from injury 
from those energies."  None of the protections specified in the standard are 
applicable to a "skilled person."  He can work on the equipment with the covers 
off.   Ralph worked on TVs with the covers off and was able to avoid injury 
because of his knowledge of the energy sources, so, with respect to TV safety, 
he was a "skilled person."  "Skilled person" is also defined in the IEC 

An "instructed person" is just that.  He must be instructed as to energy 
sources that could cause pain and the precautions he must use to avoid the 
pain.  And, he cannot be exposed to energy sources that could cause injury.  
Instruction must be by someone who knows the energy sources in the specific 
equipment and knows the precautionary measures that must be taken to avoid 
pain, which means that the instruction must be by a "skilled person."  
"Instructed person" is defined in the IEC Glossary.

Associated with the person definitions, IEC 62368-1 defines three magnitudes of 
energy.  Magnitude 1 may be detectable, but not likely to cause pain or injury. 
 An "ordinary person" may have exposure to magnitude 1 energy sources, e.g., 
low voltage.  

Magnitude 2 may cause pain, but not likely to cause injury.  An "instructed 
person" may (is allowed to) have exposure to magnitude 2 energy sources.

Magnitude 3 may cause injury.   A "skilled person" may have exposure to 
magnitude 3 energy sources, e.g., mains voltages.


-----Original Message-----
From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] 
Sent: Wednesday, November 1, 2017 2:38 PM
Subject: Re: [PSES] Regulatory requirements for MOVs placed line-to-ground on 
AC mains ports?

IEC 63386-1 seems to introduce a lot of new terms I have not seen used in other 
IEC standards.  ( but I haven't read everything out there) I would add that a 
"skilled person" perhaps is a "qualified person" , but qualification is often 
associated with formal training by an accredited institute, not just on-the-job 
experience.  I have fixed a few TVs in my time, but I wouldn't say I was 
qualified; skilled maybe.

Ralph McDiarmid
Product Compliance
Solar Business
Schneider Electric

This email has been scanned by the Symantec Email Security.cloud service.

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 

All emc-pstc postings are archived and searchable on the web at:

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 <sdoug...@ieee.org>
Mike Cantwell <mcantw...@ieee.org>

For policy questions, send mail to:
Jim Bacher:  <j.bac...@ieee.org>
David Heald: <dhe...@gmail.com>

Reply via email to