prophet@umcp-cs.UUCP (07/10/84)
<>
In my search to find a decent surge protector and line filter, I have found an
interesting fact: Practically none of the ones I have looked at are U.L.
(Underwriter's Laboratories) listed. These include high quality units ( such
as the Peach and the Orange), and more expensive units costing over $300.00.
I am interested in a surge protector/line filter made by Electronic
Specialists, Inc., of Massachusetts. When I called the company to ask why
their products are not U.L. listed, they said that their products are built to
U.L. standards, and that they back them up fully. They said the reason their
products are not U.L. listed is that the units themselves are housed in a
bakelight (sp?) cabinet, and that U.L. frowns upon this.
My question is: Exactly what does it mean when an electrical device such as a
surge protector is U.L. listed? Is it necessarily an indication of quality if
the product is U.L. listed? What might the consequences be of using a device
that is not U.L. listed? I would greatly appreciate some advice from all you
Electrical Engineers out there.
Thanks,
Dennis
--
Call-Me: Dennis Gibbs, Univ. of Md. Comp. Sci. Center.
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BITNET: GIBBS@UMDB
ARPA: prophet@Marylandhull@hao.UUCP (07/11/84)
Yep. We have a surge protector of the bakelite-body class as part of a
transient protection system at one of our mountain-top Solar Observatory
sites. It was installed in 1978 and has self-destructed twice in the time
since then - once a few months after installation, and again recently during
the middle of the night while on local generator power. Each time, the body
was blasted open, and a half-dollar size puck of bakelite ejected (presumably
at less than Mach 1). Considerable smoke and flames followed, but since the
device is installed inside a standard UL-approved NEMA enclosure, damage was
limited to the interior of the box. In each case, the 60 Ampere entry circuit
breaker place in the line ahead of the surge protector *did not trip*.
HOWEVER, it finally dawned on us that in spite of the marvelous statistical
reliability this package has shown, IF one of our observers or technicians
just happened to be standing in front of the box with the lid off when this
happened, the consequences would be very serious. The site is more than
40 miles from any hospital or medical services on a road which rental cars
are specifically prohibited (by contract) from traveling.
Replacement cost for the surge protector is $299.00, but for the observer/
technician it is substantially higher [due to the more sophisticated cognitive
systems installed in the observer :-)]
We are just beginning to discuss the matter with the manufacturer. It is
presumed that UL would be primarily concerned with *A PREDICTABLY SAFE MANNER
OF FAILURE, ONE WHICH WOULD CONTAIN THE BLAST AND FIRE, AND WHICH ALSO WOULD
LEAVE EXTERNAL COMPONENTS IN AN ENVIRONMENT NO WORSE THAN WOULD BE EXPERIENCED
IF THE SURGE PROTECTOR WERE NOT IN THE SYSTEM.* This would require a metal-
cased device and fire-proof (probably expanded mica) cushion inside.
The following is extracted from the Standard Handbook for Electrical Engineers,
11th Ed. Edited by Donald G. Fink (A McGraw Hill Publication).
"UL. Underwriters Laboratories, Inc. 207 East Ohio Street, Chicago, Ill 60611,
H. Baron Whitaker.
Founded in 1894, UL is an independent, not-for-profit organization which
maintains and operates laboratories for testing devices, systems, and materials
with relation to public safety. Products so tested and meeting its requirements
are eligible for UL 'listing.' UL maintains an inspection and follow-up program
in factories where UL listed devices are manufactured. UL representatives
conduct in-factory and in-the-field inspection of manufacturer's procedures for
assuring production compliance with UL requirements. Such requirements appear
in appropriate UL Standards for Safety which are developed by UL under
procedures that involve consultation with industry and government experts and
consumers, among others.
Services available from UL include:
UL's listing and follow-up service, applicable to products evaluated with
respect hazards to life and property."
...Three other services itemized in the text...
...Relationship to government and organization
of the lab discussed, & departments listed...
"UL publishes (lists) the names of companies who have demonstrated the ability
to provide products conforming to its requirements. Listing authorizes the
manufacturer to use the Laboratories' listing mark(classification marking,
recognition marking, or certificate) on the listed products.
Underwriters Laboratories submits its standards to ANSI for adoption as
American National Standards. It presently uses the canvass method almost
exclusively to achieve national consensus. In addition, it is active in
international standards, is represented on the Executive Committee of the
USNC/IEC, and provides experts and technical advisors for developing U.S.
positions for IEC and ISO committees."
Regards, Howard Hull
{ucbvax!hplabs | allegra!nbires | decvax!stcvax | harpo!seismo | ihnp4!stcvax}
!hao!hullseifert@ihuxl.UUCP (D.A. Seifert) (07/25/84)
A UL listing doesn't guarantee quality. You can walk into
most any store which carries electrical/electronic products
and find all sorts of trash that has a UL stamp on it. What
it supposedly does is give a *reasonable* assurance of safety.
If you believe their story that their product is UL except
for the bakelite box, then find out *why* UL frowns on the
bakelite box and then decide if their reason(s) apply to
your application.
It does seem really odd that none of them are UL listed.
If I were trying to sell these things, I would definately
want to get the thing UL approved.
--
_____
/_____\ "Get out there and keep moving forward!"
/_______\ - Leo Franchi
|___| Snoopy
____|___|_____ ihnp4!ihuxl!seiferttech@auvax.UUCP (Richard Loken) (07/26/84)
The Underwriters Laboratory is interested in safety not quality - they don't really care how well it works as long as it doesn't eat small children or something. Their standards are to some degree a matter of opinion - ie in Canada the usual referance for safety is approval by the Canadian Standards Association while in the US it is preferred if a device is listed by the UL. Note that their acceptance referred to differantly - the UL insists that they do not approve anything (they list it) while the CSA sticker says approved whateeveritis but in addition, they have slightly differant require- ments for approval (the CSA in one case in a Short Wave receiver that I own requires a 1Mohm resister between the grounded and grounding wires that the UL listing did not require). In short, I beleive in the UL with all my heart and all my soul and I wouldn't take a bakelite surge protector as a gift since it just might explode all over the place. Richard Loken