I agree with your sentiments below but they don't explain how using the IT
standard can make an audio product safer.  Are you sure that the creepage
and clearance distances are more stringent in 950 than they are in 65?

Chris Colgan
Compliance Engineer
TAG McLaren Audio Ltd
The Summit, Latham Road
Huntingdon, Cambs, PE29 6ZU
*Tel: +44 (0)1480 415 627
*Fax: +44 (0)1480 52159
* Mailto:[email protected]
* http://www.tagmclaren.com


> -----Original Message-----
> From: Gregg Kervill [SMTP:[email protected]]
> Sent: 27 September 2001 20:57
> To:   'Colgan, Chris'; [email protected]
> Subject:      RE: Applying the appropriate ENs
> 
> I feel that we are missing the point of Product Safety and trying to
> over-simplify the issues (please read John Woodgate's excellent reply).
> 
> The culture for product safety is totally different to that required for
> EMC
> and Functionality testing.
> 
> 
> Let me answer by giving another example - also real life......
> 
> A company designs a motor speed controller rated 250 kVA. It is
> programmable
> via an external PC thorough an RS232 port.
> Question - what standard do we take the Creepage and clearance distance
> from.
> 
> ANSWER - EN60950
> 
> Reason:- the PC user accepts a certain level of risk when using the PC.
> That
> level of risk is defined by EN60950.
> 
> If the Motor Controller RS232 port does not provide the SAME LEVEL OF
> PROTECTION (i.e. those defined by EN60950) then the user will be exposed
> to
> a higher level of risk.
> 
> The Product Safety Engineer MUST consider WHAT can go wrong - HOW might it
> be used - How might it be connected - How can someone be injured - etc. So
> in our previous example - let's think of a situation where the motor
> controller might be connected to a computer network and the implications
> of
> that.
> 
> YES there are limits (the poodle in the microwave oven) BUT there are
> plenty
> of real life examples where cutting corners - or failing to take into
> account had serious outcomes.
> 
> Examples from history - Titanic (material failure) - Challenger (O-ring
> failure) - Zeebrugge (failure to follow instructions). ALL could have been
> avoided given 20-20 hindsight
> 
> 
> 
> This is a fundamental issue and the correct understanding and application
> of
> it is the foundation of everything that product safety is about.
> 
> 
> I believe that it is the role - the duty and the responsibility of Product
> Safety Engineers to close the odds on those and similar tragedies
> occurring.
> Sometimes we will get it wrong - and when we get it right no-one will
> notice - but I do not see any option.
> 
> 
> Best regards
> 
> Gregg
> 
> 
> -----Original Message----- with a big SNIP ----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Colgan, Chris
> Sent: Thursday, September 27, 2001 9:21 AM
> To: [email protected]
> Subject: RE: Applying the appropriate ENs
> I don't understand how testing to a different standard can make a product
> "safer".  If there is a product specific standard, use it.  If you are
> testing a CD Recorder (presumably what you mean by a CDR) then you should
> use IEC60065.  If you want to exceed the requirements of IEC60065 then you
> are of course at liberty to do so.
> 
> IEC60065 has been written by people who understand audio/video products,
> the
> same may not apply to the people who wrote IEC60950.


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