Use caution once again. IEC 60825-2 is NOT single fault. You need to
go further and consider if a condition is "reasonable foreseeable" even
if you need multiple faults to get there. Often there is congruence
between single fault and reasonably foreseeable, but not always.
>From 60825-2:
reasonably foreseeable event
event the occurrence of which under given circumstances can be predicted
fairly accurately,
and the occurrence probability or frequency of which is not low or very low.
Examples of reasonably foreseeable events might include the following:
component failure,
fibre cable break, optical connector disconnection, operator error or
inattention to safe
working practices.
Reckless use or use for completely inappropriate purposes is not to be
considered as a
reasonably foreseeable event
The assessment of hazard levels shall always consider worst case
conditions, including
reasonably foreseeable fault conditions (see 4.4.3). Consequently, it
may be necessary to
include multiple fault conditions, the probability of which shall be
judged by the
responsible organization.
NOTE Whereas IEC 60825-1 refers to single fault conditions, it may be
reasonably foreseeable that more
than one fault will combine to cause a dangerous situation.
FDA laser notice 50 issued in July of 2001 allows you to harmonize with
IEC 60825-1, so as long as you slightly modify your FDA certification
statement label to note that you are using the deviations in Notice 50
you can use the IEC 60825 labels. The FDA is contemplating a rule
making to adopt the IEC versions and has therefore put manufacturers on
notice that they will not take enforcement action against those choosing
to use the IEC standards. Note that you still have additional
administrative requirements under the CDRH rules.
Jon Curtis
Curtis-Straus LLC
Davis, Mike wrote:
I agree with Doug and with John but, I have the same question. And I will
add, Doug is speaking of the FDA-CDRH requirement for the US. But, to
ascertain what the European mode is, this requires a single-fault condition
for classification as described by John Juhasz. That, I understand. John, is
there a free downloadable copy of ANSI Z136.1 and .2 specs?
I have used the calculations to determine the classification of a laser
based on the no fault and a single fault mode. These lasers are operating in
a pulsed mode at a 50% duty cycle. I have attached a sample calculation of a
1310nmn and a 1550nm laser that I used to determine that the lasers either
do or do not fall within the Class 1 laser classification. Another
question...
Can the same label be used for FDA as for IEC? Has anyone had any feedback
or problems with laser labels that deviated from recommended markings by the
21 CFR or IEC 825-1?
------------------------------------------------------------------------
Subject:
Re: Laser Safety
From:
Doug Mckean <dmck...@corp.auspex.com>
Date:
Tue, 5 Mar 2002 17:16:54 -0500
To:
emc-p...@majordomo.ieee.org
Do the acid test type question ...
During normal use, what are you exposing the end user to?
For instance, with a laser pointer using a Class IIIb
laser that emits unprotected from the pointer, the
pointer is Class IIIb.
If instead, you are using a Class IIIb laser for fiber optic
communication and the entire beam is contained within
the fiber, no lasing is emitted from the product during
normal operation and/or service or maintainance, then
you *could* declare the telco product as Class I.
- Doug McKean
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