tage of having some low-voltage expertise is the ability to
schedule these projects in-house. The more we can do is also
more revenue. If we are competitively bidding and the scope
for the work is Division 27 [communications systems and
related infrastructure] or Division 28 [electronic safety
and security systems and infrastructure], we will
subcontract with low-voltage firms. With these
bigger IT-centric projects, low-voltage-only
contractors do the design. Then we step in to
do the physical installation.”
In the markets served by Pacific Elec-
trical Contractors, Myers has seen
network-based controller configurations
technologically evolve in fire alarms and
nurse call installations. For example, low
voltage has allowed today’s control sys-
tems to operate on fewer cables, making
“It’s become a plug-and-play world,” he said.
Ten years ago, the company was busy
installing data cable throughout medical facilities. It has since been called back to many of these
facilities to install networked systems.
“It was a future-proofing effort on the part of these customers,” Myers said. “Now, we are applying today’s technology that
takes advantage of a low-energy cabling infrastructure so customers can perform daily processes faster and cheaper; allow remote
access. In our industrial sector, a lot of controls are programmable
logic controllers connected through Cat cable. Every sensor is
hardwired. In the office, and to a degree in industrial settings, we
set a wired infrastructure but add a wireless network on top of it.”
Though the residential market isn’t the company’s core
business, low voltage has played a big part in it.
“We see low voltage applied as wireless control of the home
thermostat, door bells, security and other areas,” Myers said.
“With home routers and smartphone apps, it seems the home-
owner is probably leading the way with wireless.”
The company’s municipal work also is touched by low volt-
age, as roadway lighting becomes networked and communicates
through overhead controls or underground fiber optics. This has
enabled remote troubleshooting and quick traffic management.
The Code takes notice
Myers has seen a transition in how ECs deal with low-voltage work.
“Some 20 years ago, little care was taken with low-voltage
installation,” he said. “Due to the sheer volume of this work and
its rapid growth, low voltage is now referenced more specifi-
cally in the NEC [National Electrical Code]. In-house quality
control and outside inspectors have also emerged. In fact,
installation inspection is required in many states.”
The 2017 NEC provides new and specific guidance regard-
ing low-voltage cabling. As building controls meet greater
demand, more energy runs through low-voltage cable, present-
ing potential for overheating cable.
“More and lower energy devices have come online,” said Mark
W. Earley, P.E., chief electrical engineer, National Fire Protection
Association, Quincy, Mass. “Cables that formerly only carried
data signals are now being used to supply power to connected
devices including lighting [also known as power over ethernet].
The internet of things [Io T] is serving as a sort of launching pad
for more low voltage. This has focused us to go back and take a
While clarifying amendments are being discussed, the 2017
NEC addresses the issue of heat buildup in low-voltage cables in
two ways: the conductor capacity of certain bundled cable must
be limited, and bundles must be limited to four pair cable per
bundle. Such direction is referenced as transmission of power
and data (Article 725) and premises powering of communication
equipment over communication cable (Article 840).
“Some jurisdictions have not inspected communications
or data circuits because they are not power circuits,” Earley
said. “In the past, these circuits have not produced much heat.
Now some will and so there is a greater need to inspect them
for code compliance.”
Though definitions of low voltage vary, Earley prefers the
National Electrical Manufacturers Association (NEMA) fram-
ing of anything 1,000 volts or lower.
“If we are using the 1,000-volts definition, it is the work
most contractors are doing now,” he said. “Some will refer to
Lighting controls marry low and high energy.
Curriculum for low-voltage installation
has expanded through the Electrical