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Electrical Maintenance Pays Dividends ELECTRICAL DESIGN LIBRARY
Electrical Maintenance Pays Dividends ELECTRICAL MAINTENANCE CONCERNS ................................................................ 1
POWER DISTRIBUTION SYSTEM SERVICE ............................................................... 3
Electrical Design Library (EDL) publications are prepared for architects, consulting
engineers, and qualified electrical contractors, as well as owners, developers, investors,
and their electrical construction specifying personnel. Issued periodically by the National
Electrical Contractors Association (NECA), the publications provide factual explanations of
the increasing variety of sophisticated electrical systems and the economics of their
installation by professional electrical contractors. They are distributed by the Associations
chapters, located in all sections of the United States. This EDL is the result of ongoing
research being sponsored by The Electrical Contracting Foundation, Inc. into electrical
service contracting by The University of Kansas.
©Copyright 2004 by the National Electrical Contractors Association. All rights reserved.
Published by the National Electrical Contractors Association, 3 Bethesda Metro Center,
Bethesda, Maryland 20814.
Contents
Index No.
3025111
Marketing
9K/10/04 PAGE 1
Electrical Maintenance Concerns
S
ince most building power
distribution systems are
radial, the failure of any
downstream component will interrupt
all upstream loads. Such power
disruptions usually result in lost
production and sales, events that
directly impact the bottom line.
Building power distribution systems
are no different than other building
systems. Over time and with use, the
components that make up a power
distribution system degrade and need
to be maintained or replaced.
However, other building systems
offer an advantage. They usually fail
graduallyfor example, small leaks
through the ceiling, which allows you
to take corrective actionreplace or
repair a roofbefore catastrophe
occurs. With power distribution
systems, wear or system failure is
rarely immediately visibleout of
sight and out of mind.
Regular maintenance programs are
key to getting advance notice of
impending power distribution failure.
They reveal problems such as discol-
ored insulation or overheated conduc-
tor terminations that allow you to take
early corrective action. They also
increase the chances that
uninterruptible power supplies (UPSs)
will actually operate properly in an
emergency.
Further, poor electrical mainte-
nance is expensive. It causes unnec-
essary equipment replacement,
preventable repairs, avoidable service
disruptions, and prolonged downtime.
This Electrical Design Library
discusses issues to consider when
creating an effective
electrical maintenance
program.
Environmental
Concerns
Effective electrical
maintenance should
address both the electrical
environment and the
physical environment
where equipment operates.
Motor and transformer
life expectancy decreases
significantly when the
equipment is operated for a
short period of time at
temperatures only moder-
ately above the rated
insulation temperature.
Excessive heat causes
insulation failure and
internal short circuits.
Excessive heat may be
generated when transform-
ers and motors operate in
unconditioned and
nonventilated spaces,
ventilation openings are
blocked, ventilation fans are
inoperable, or dirty air filters
dont get replaced.
Similarly, exposing
distribution equipment to
dust and moisture it is not designed to
handle will shorten its life. Dust and
moisture can lead to arcing and
insulation failure. Further, dust buildup
reduces the ability of equipment to rid
itself of excess heat, which leads to
insulation failure.
Electrical equipment must be
selected and rated based on the
environment where it will be placed.
After installation, the equipment needs
to be inspected and cleaned regularly
Poor electrical maintenance is
expensive; it leads to avoidable
disruptions and prolonged
downtime PAGE 2
so that corrective action can be
taken and premature failure of the
equipment can be avoided.
Other Concerns
Age and use are not the only
things that impact the reliability of
a buildings power distribution
system.
Few people would install a new
piece of production equipment in a
building without first checking to
make sure that the structure could
handle it.
However, new and different
loads are added to building power
distribution systems each day
without anyone questioning whether
or not the system can handle them,
how the loads will affect the
operation of other system loads, or
how reliable power distribution
system components are.
Managing power distribution is
complicated enough day-to-day
with mechanical and production
equipment cycling on irregular sched-
ulesto not take into account the
effects of changing load characteris-
tics and power quality requirements as
electronic data processing, communi-
cations, and control equipment are
added to the system.
If everything is sized properly,
overloads and short circuits will be
cleared by the circuit breaker or fuse
protecting the circuit. Still, repeated
overloads and short circuits weaken
system components over time and
result in premature equipment failures.
In addition, every time that a feeder
or branch circuit is opened due to an
overload or short circuit, the systems
fed by that circuit are down until the
problem is identified and corrected.
Further, system conditions such as
harmonics, voltage imbalance, chronic
low voltage, and system transients
often go undetected by circuit break-
ers and fuses. They can, however, be
detected and corrected through an
ongoing maintenance program.
Why is this important?
If undetected, these conditions can
result in overheating and insulation
failure of distribution system compo-
nents that will result in a short circuit
and power interruption.
Exposure to dust and moisture is one sure way
to shorten the useful life of electrical equipment. PAGE 3
W
hen putting together
an effective power
distribution mainte-
nance program, consider the types of
maintenance required in your facility.
Power distribution system service can
be divided into the following three
categories: Demand Service Scheduled Service Programmed Service
Demand Service
Demand service refers to service
that responds to your immediate need.
Typically, demand service occurs
when your system or piece of equip-
ment has failed or is operating at a
significantly reduced capacity and is
affecting your ability to carry on day-
to-day business.
Demand maintenance is often the
result of a run-to-failure (RTF) mental-
ity. Unexpected failure of electrical
equipment can never be eliminated.
There will always be equipment that
fails unexpectedly or fails for reasons
other than just wear and tear, such as
accidents and acts of God.
However, ongoing inspection and
maintenance can identify problems in
advance and help avoid sudden
failures. By identifying potential
problems in advance, you can plan
corrective maintenance around your
operations with scheduled service.
Programmed service is designed to
reduce the amount of demand service
you need.
Power Distribution System Service
Scheduled Service
Scheduled service refers to service
that is planned and scheduled in
advance with the customer. Scheduled
service can include moves, adds, and
changes (MACs or MAXs) to an
existing system to better meet needs.
Scheduled service can also involve
the repair of noncritical or redundant
systems or equipment that have failed
or are running at reduced capacity.
Scheduled service can also occur
when a system or piece of equipment
is suspected to be near failure.
Programmed Service
Programmed service includes both
pre-scheduled and trigger-point service.
Pre-scheduled service includes
preventive maintenance that occurs on
regular intervals. These intervals are
determined by a parameter such as
NEIS Standards Offer Maintenance Guidance
While all NEIS are created to make electrical and datacom system
maintenance easier and less expensive over a buildings life, many of
these installation standards specifically deal with maintenance. In
each case, a short PDF is availablefreewhich contains the
individual documents table-of-contents and scope.
Some sample standards and Web URLs for downloading of the PDFs