Recent events have reshaped the
world and increased building
safety awareness in North
America. During the past
decade, more and more design engineers
are putting fire safety at the top of the priority
list and specifying products that keep
a building’s critical electrical system intact
longer, while protecting emergency
personnel in the event of a disaster.
Technically Advanced Wire Cable
Trays Hold Fast in Fire
One safety concern being addressed
more by U.S. engineers today is a building’s
overhead wiring. As offices become
more technically advanced, more cabling
is needed for both power and communications.
In many cases, much of the cabling
is managed above the ceiling in the air handling space above the ceiling tiles,
since it is the most readily available
space. Sometimes, it is supported in aluminum
ladder trays, plastic netting or “J”
hooks. In a fire, these cable management
systems can easily fail and bundles of cables
can fall, rendering the building’s vital
services inoperable, blocking
evacuation routes and hindering emergency
response personnel.
Having the overhead wiring stay in
place during a fire extends the functionality
of a building’s critical services, such
as emergency lighting and fire alarms,
helps to keep the egress of a building
open for occupants to escape, and lessens
the amount of tangled debris that emergency
personnel must search through during
and after a fire.
Cablofil, located in Mascoutah, IL, is
the first wire cable tray, support brackets
and hardware to be certified E-90 according
to German standard DIN 4102-12:
1998-11. Cablofil is constructed of highstrength
steel wire, making it inherently fire safe, durable and extremely strong.
The German standard serves as the
global reference, since it is the only standard
available specifically referring to fire
resistance for cable trays. The test configuration
was comprised of a 4.1-foot Cablofil
cable tray with a maximum
permissible load of 6.7 lbs. The temperature
of the test fire was raised according
to the temperature curve (ETK) defined
by DIN 4102-12.
The German standard DIN 4102-12
specifies that the complete system of cable
trays, accessories and cables must be
tested in an oven measuring at least 3m
long, for a period of 30, 60 or 90 minutes
up to a temperature of 1000ºC or 1832ºF.
The purpose of the test is to validate the
correct operation of the electrical system
and to ensure that the critical services
(emergency light-ing, fans, emergency exit, fire alarm, etc.)
remain functional for long enough time to
organize a rescue in the event of a fire.
“I have seen buildings where MI cable
was put into aluminum ladder tray,” said
Tim Place, president of Cablofil. “During
a fire, the ladder tray would have completely
failed leaving the cables sagging
and unsupported. This would have probably
resulted in a short and early failure of
the feed.”
MI cable (mineral insulated) is often
specified for mission critical circuits. MI
cable is an older technology, but a very
durable type of cable. It was originally designed
for use in submarines to carry power
circuits. MI cable has a copper sheath filled
with mica powder that insulates the inner
conductors from intense heat.
Cable management systems made of other materials have been proven to fail
during a fire. Aluminum has been found
to melt at 900º F and plastic at 300º F. The
Cablofil wire mesh trays, cable and supporting
hardware were able to withstand temperatures of more than 2,000º F for a
period of 90 minutes.
“In many cases, the performance of an
electrical system in an emergency is the
primary consideration,” said Place. “Understanding
how components react when
exposed to fire is essential. Cablofil’s steel
construction is proven to meet the E-90
standard, essentially providing a 1.5-hour
fire rating.”
U.S. fire and electrical safety codes currently
do not require the installation of “fire safe” wire cable trays in structures,
and there is no fire safety certification in the U.S. for wire cable trays. NFPA 101 “Life Safety Code” Chapter 7 has requirements
for the separation of rooms,
like the requirement for a one-hour fire
rating for exit corridor walls, but none directed
to the overhead structures inside of
facilities. Awareness of Cablofil’s product
and its fire safety benefits have been
brought to the attention of the National
Fire Protection Agency, which is currently
researching the issue. Additionally, Cablofil
wire cable tray meets all applicable
U.S. standards and requirements including
NEC, UL, NEMA,
CSA and ANCE.
Having wire cable
trays that can withstand a
fire is vital for life safety
in arenas, stadiums, commercial
schools or any
facility with significant
personnel capacity. Fire
safe cable trays ensure
that means of egress are
not blocked by falling cables
or cable supports,
which is critical for
emergency workers already
working in a dangerous
situation. They also ensure that
support is maintained for critical circuits
such as fire alarms, security and fire
pumps.
“A recent spec just came to us from a
New York project that wanted to make
sure that the emergency pump feeds at a
two-hour rating, versus the local code
standard of an hour,” said Place. “I see
more of this all the time.”
As an added safety feature, Cablofil cable
trays feature Safe-T-Edge, a unique
process that T-welds the lateral wires to
the top wire to create a smooth edge that
minimizes the risk of frayed cables and
protects installers from sharp wire ends.
This is an important feature when adding
or changing wires in a cable management
system. Also, Cablofil’s
patented Optimized Wire design keeps
Cablofil lightweight, yet strong, making
it able to hold more than 50 percent of its
capacity.
Cable Management Solutions
in Earthquake Zones
In addition to being fire safe, the
welded wire structure of Cablofil cable
tray withstands earthquake conditions to
a superior level. It is comparable to a net -
it flexes and bends but doesn’t break.
Other more rigid cable management systems
fail when subjected to swaying and
flexing conditions endured in a seismic
event. Cablofil can be equipped with Seismic
Bracing that prevents longer runs of
cable tray from swaying side-to-side.
Having this type of seismic resistant cable
management in place is particularly
important in buildings located in high-risk
earthquake zones such as the Midwest and California. Officials in these areas have
adopted strict seismic building codes that
are being strongly enforced throughout the
construction process. Seismic building
codes are not only being enforced in new
construction, but many older buildings as
well. Buildings constructed as recently as
the early 1980s are undergoing major remodeling
to conform to the newer, stricter
standards. Upgrades on older buildings
can be a difficult and expensive.
Local officials are taking these seismic
building codes very seriously, with strong
consequences for those who break the
rules. Violations in seismic building codes
can result in the denial of occupancy permits,
civil lawsuits, fines and the revocation
of licenses of engineers, contractors,
architects and anyone else involved in the
design and construction of the building.
Wire Cable Tray Has its Roots
in Europe
Since its introduction, Cablofil wire cable
tray has proven to be a safe, sensible
choice for cable management in virtually
any type of installation. First marketed in
Europe in 1972, Cablofil is one of the best
known and most specified brands of wire
mesh cable tray in the world. With over
90,000 miles of Cablofil cable tray installed
worldwide, it is a proven product
recommended by engineers and installers
everywhere. “Cablofil sets the pace in product innovation,
quality control, labor saving products
and timely delivery for more than 30
years,” said Place. “Our ongoing research
and development allows us to find better
and more cost-effective ways to make cable
management even easier.”
While wire mesh cable
tray has been widely used
to support power cables
throughout Europe for
more than 30 years, contractors
in the U.S. and
Canada have only recently
begun to take advantage of
the significant cost savings
and safety features that
these systems provide
Cablofil is Flexible
and Easy to Install
Easy installation, flexibility
and safety considerations
are the primary
reasons why forward-thinking contractors
are choosing wire mesh cable tray. When
combined with MC cable, wire mesh tray
has been found to be a safe, reliable and
cost-effective alternative to conduit.
Unlike conduit, wire mesh cable tray,
which is an open system, requires no special
bending equipment and does not require
the lubing of wires or the installation
of pull boxes. By making simple cuts in
the wire tray, installers can form 90-degree
radius bends, 90-degree vertical
bends or specialized bend combinations,
allowing the tray to wrap around HVAC
units or to avoid other obstacles.
Also, unlike other open systems such
as ladder or trough tray, wire mesh cable
tray does not require special pieces to
make corners, Ts, up/down angles or intersections.
The standard 10-foot lengths
of wire mesh tray can be modified easily
on site using a bold cutter, screwdriver
and wrench to make directional changes.
Nobody knows when a fire or disaster
will strike, but by utilizing commonsense,
cost-effect products, like Cablofil,
that are carefully tested against stringent
safety guidelines, building-owners and the
people who inhabit those buildings can
feel secure knowing that the cables overhead
are going to stay in place and work
as designed before, during and after a disaster.
Think of it not only as buying the
latest technology available, but buying the
time it takes to save lives. Isn’t that most
important?
Bob Crain is a registered professional
engineer and Technical Sales Manager
for Cablofil, a U.S. manufacturer of
cable tray based in Mascoutah, IL.
