Well, just briefly. The backwards UR is a component recognition. It can
be used in a end unit only if the conditions of acceptability that are placed
in the UL report are met. E. G. Power supplies would have obvious things like
the end use product must provide and adequate fire enclosure etc. Less obvious
might be the requirement for a specific amount of airflow across the power
supply itself - this one can bite the unwary.
The UL in a circle indicates a Listed product - those products that are
fully ready for a user. Plug it in and go. A computer for example. (Inside of
which is probably a recognized power supply - which is now properly housed and
cooled)
Then there is the ULc which means its a listed product and evaluated to
bi-national standards for the US and Canada. (CSA has a similar mark)
There are actually other forms of markings as well, the words
Underwriters Listed for example could be used instead of the UL in a circle
thing. Then there are Classified items such as sheet rock, roofing materials
etc. Haven't a clue what that marking looks like.
I suppose there are variants that I haven't mentioned but these are the
essentials to your question I believe.
Gary
-----Original Message-----
From: Chris Maxwell [mailto:chris.maxw...@nettest.com]
Sent: Friday, February 22, 2002 6:40 AM
To: EMC-PSTC Internet Forum
Subject: Different shades of UL
Hi all,
I know that this has been covered before. But please indulge my
ignorance.
There are many different forms of UL marks, each with subtle
differences.
There is the "UL" in a circle. There is also the mirror lettered "RU".
There are also some subscripts denoting approval for Canada as well.
There may be some other variations that I can't remember. Anyone care
to blow a few minutes on a Friday afternoon to explain which symbol
means what?
Thanks,
Chris Maxwell | Design Engineer - Optical Division
email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797
8024
NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA
web www.nettest.com | tel +1 315 797 4449 |
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