PSNet - including Mel Pedersen...
Why would you, Mel, look any other place then to UL for a Plastics
Recognized Component Directory? From the beginning of their history UL has
focused on fire prevention in electrical installations and equipment. This
focus has been reinforced because of the North American use of lower
voltage for commercial and residential systems than those used in Europe
and much of the rest of the world. This lower voltage (V/2) draws a higher
current (2xI) which leads to 4x the heating effect (remember I**2 x R) and,
historically, more fires in equipment and installations. This UL focus
joined with the other forces at work within UL to develop methods for
pre-qualification of plastic materials for use in installation components
(wiring, switches, outlets etc) and equipment. Thus, the world's largest
public database - the UL Plastics Recognized Component Directory.
The European approach (until more recently) was not to qualify
materials, but qualify parts and pieces of construction using tests such as
the Oxygen Index test on finished pieces. This methodology meant that the
same material used in another configuration would be tested again and
again. So there is plenty of European data, but it doesn't seem to be
published in any useable form available to worldwide users.
With the ongoing harmonization of standards on a worldwide basis,
even the Europeans recognize the benefit of pre-qualification of materials
and have been accepting this approach in many standards... IEC 950 and IEC
1010 make heavy use of these prequalified materials to demonstrate adequacy
in any application... Moreover, over the last 20 or more years, UL has
been quietly moving their requirements into IEC (e.g. IEC 60674 -1, 2,
3-2,3-3, 3-4 to 6, 3-7 (and European standards)) so that the UL database is
now more important than ever in showing compliance to the requirements
stated in the standards... Further, plastics manufacturers worldwide
submit their materials to UL for evaluation enlarging the usefulness of
this database.
There is some competition, CSA publishes a directory...
CAN/CSA-C22.2 No. 0.17-92 (R1997) evaluation of Properties of Polymeric
Materials. The Canadian requirements shadow the UL requirements. They
have been accepting materials for evaluation for the last 10 years or so.
The last CSA directory I used was quite a bit thinner than the UL
directory...
Well, I didn't intend for this to be a UL sales pitch, but do
believe that their large database will be the basis of choice for selection
of plastics materials for use in equipment meeting worldwide requirements.
- - - - -
Peter E Perkins
Principal Product Safety Consultant
Tigard, ORe 97281-3427
+1/503/452-1201 phone/fax
[email protected] email
visit our website:
http://ourworld.compuserve.com/homepages/peperkins
- - - - -
