User manual

“We’re The Company Without
a Blimp”
Underwriters Laboratories has become
something of an icon always associated
with US product safety. William Henry
Merrill chartered Underwriters
Laboratories, Inc. in Illinois in 1901. He set
up a small lab in Chicago to test electrical
devices. Over the past 100 years, UL has
tested more than 12,500 different types of
products and employs 5,000 people
worldwide. UL is a very successful not-for-
profit testing organization totally
supported by fees charged to clients. UL is
very independent and, certainly, the most
widely recognized mark in the US and in
more than 70 countries.
But, UL is not the only acknowledged
safety-testing authority. There are several
others with equal credibility. Next to UL in
the US is ETL Testing Labs. Somewhat like
B.F. Goodrich, the tire company that
advertised in the 60’s and 70’s: “we’re the
other company without a blimp.” ETL is an
internationally recognized, fully independent
testing company. The ETL mark is widely
recognized as equivalent to UL. All test
methods and standards used by either
organization are identical. Many people are
not familiar with ETL, I believe, because they
attained recognition as a Nationally
Recognized Testing Laboratory (NRTL) in
1989…relatively recent compared to UL.
Other testing laboratories such as TUV
and Dash, Strauss, and Goodhue, Inc. are
well known as testing authorities. TUV
began in Europe and its services have been
available in the US for many years.
Recently, Inchcape Inspection and Testing
Services, a US corporation, absorbed ETL
Testing Laboratories and Dash, Strauss,
and Goodhue. However, the ETL mark
survives this acquisition.
Trends in Changing Standards
The NFPA 262 (UL 910) standard is
undergoing changes. Several adjustments
January/February 2001 ExtroNews 12.1 9
TECHNICALLY SPEAKING...
While PVC contains chlorine, it is not
fire resistant. PVC and polyolefin
products must have concoctions of
other elements added in order to
achieve any degree of flame resistance.
Most fire resistant compounds contain
fluorine or are said to be fluorinated,
such as FEP (fluorinated ethylene
propylene).
I Can’t Believe It’s Not Halogenated!
European building authorities will not
allow use of halogenated cables. When
halogen-based cables burn (at whatever
level they will produce smoke), the
smoke is corrosive and contains
poisonous gases. There is high concern
about the true safety of halogen-based
cables. More information on the
move away from halogens in cable
insulation may be obtained at:
www.halogenfree.org.
While the European Union designs
the safety tests for that region, there is
great debate over the relevance of their
position on cable flame retardancy and
safety versus that in the US. All cabling
sold in Europe must be halogen-free.
Halogen-free polymers require other
formulations of compounds in order to
obtain low smoke cable products.
Ratings? We Don’t Need
No #@&% Ratings!
The cable rating to use on a project is,
first and foremost, dictated by the
local building authorities. Always check
on your local codes before committing
to the design. Generally speaking (for
the US), general-purpose cable, like
CL2, is acceptable in enclosed raceways
and protected regions not used as
air plenums. Cables run between floors
in air spaces must be riser grade
minimum or else run within metal
conduit. Cables run in horizontal air
plenums must be plenum-rated, or run
in metal conduit.
to the procedures and calibration of the
Steiner Tunnel are anticipated to affect the
qualification of some plenum cables. As
more and more computer network
installations take advantage of plenum
communications cables in air spaces above
ceilings, there is new concern by fire safety
officials that, over time, the buildup of old,
unused plenum cables (primarily this
affects the plethora of CAT 5 type
communications cable) left behind as
systems change is creating additional fire
load that could be cause for concern. We
are likely to see NFPA 262 change in
this area.
In the UK, a Steiner Tunnel is being
installed to allow investigations of US
testing methods with fluorinated polymers
compared to the European position
against halogenated cables. Eventual
harmonization between the US and Europe
could show that our flame test is more
stringent and that halogen cables are not a
bad approach as long as emissions are very
low. Only time and a lot of testing will tell.
Cheap At Any Price?
There is definitely a cost reason for
using plenum cable in commercial
installations. I don’t have specific numbers
on the comparison and it would vary
widely due to local building codes and
labor rates. The popularity of plenum-
rated cable pretty well tells the story. If
you have not used plenum on a job, then
talk to those that have to get real
numbers for your area and situation. I can
say that the incremental cost of plenum is
only a fraction of the cost of labor to run
standard cable within metallic conduit.
However, one hidden concern might be
the cost to clients for the removal of old
cables should code authorities require the
removal of old plenum cables with system
design changes. And yet, the current pace
of business change essentially requires
that system designs be easier and faster
to install.