Emergency systems in buildings or
structures can vary in size and complexity. Some basic
emergency systems provide illumination of the egress paths
through unit equipment connected to local area lighting
circuits. Other more complex and multiple function emergency
systems provide power not only for lighting for the egress
path but for many other essential functions, such as smoke
control systems, life support systems, fire pumps, life
support systems and equipment, etc.
This article focuses on several essential
elements of inspecting all emergency systems, starting with
the electrical system plan review and not ending until the
satisfactory completion of the witness test.
Electrical System
Plan Review
If there is an engineered set of plans for the project, the
engineer’s design should be followed. When the building
inspection department includes a plan review process as part
of its construction permit and conformance assessment process,
the plan review of the project is generally the first part of
a complete code-enforcement program.
Plan reviewers verify the emergency source
to be used, the distribution system, and the lighting provided
in the egress paths and at exits. On more complex systems,
other loads should also be verified. It should be noted that,
generally, only emergency loads are permitted to be connected
to the emergency system, and these could include more than
just lighting loads in some cases [see FPN No. 3 to 700.1].
The type and location of the emergency system source as well
as transfer equipment must be checked. The load on an
emergency system should also be verified to determine adequate
capacity of the system in accordance with 700.5. This
requirement assures enough system capacity to power all
emergency loads at the same time, which becomes even more
critical if there are high capacity emergency loads, such as
fire pumps, connected to the emergency system. Although any
misjudgment in calculating the system capacity will become
apparent during the system witness test or load-bank testing,
problems can be more easily addressed at this early stage.
There are other important elements of the
emergency system design that should be checked in the plan
review process. When the emergency system consists only of
unit equipment (battery back-up) illumination for the egress
paths and exits, then verification of the circuits to which
that equipment is connected should be verified.
The plan review team must work
cooperatively with the electrical field inspection staff. This
is the most thorough and effective method of attaining
code-compliance. When there is no electrical plan review,
whether it is a small alteration or a larger and more complex
project, the job of the electrical inspector in the field is
much more difficult. It is the field inspector who provides
the final and time-consuming verification that electrical
installations and systems meet the minimum requirements of the
applicable codes and standards. The importance of electrical
plan review to the code-conformance assessment process cannot
be understated. It is essential.
Capacity of the
Emergency System Source
Arguably the most important characteristic of the emergency
system is that it has adequate capacity for the intended load.
There are a few key inspection issues that relate directly to
the capacity of an emergency system, and which differ based on
the type of system or source used.
When inspecting a battery-powered system,
verify that the charging and storage capacity of the batteries
meet the time durations and other specific
requirements contained in 700.12(A). Battery powered systems
must operate under emergency conditions for a minimum of 1½
hours and the voltage applied to the load must not fall below
87½ percent of the normal battery voltage.
If unit equipment (battery back-up units)
is provided as the emergency system, the equipment must
consist of the following components in accordance with
700.12(F):
1. A rechargeable battery
2. A battery charging means
3. Provisions for one or more lamps mounted
on the equipment, or shall be permitted to have terminals for
remote lamps, or both
4. A relaying device arranged to energize
the lamps automatically upon failure of the supply to the unit
equipment (see photo
1).
Or the unit equipment shall supply and
maintain not less than 60 percent of the initial emergency
illumination for a period of at least 1½ hours. Unit
equipment, generally, is required to be connected to the
normal lighting branch circuit serving the area and is
required to be connected to the branch circuit ahead of any
local switches to maintain continuous power to each unit. An
exception to 700.12(F), for separate and uninterrupted areas
served by at least three branch circuits, allows a separate
branch circuit to supply the unit equipment for the area as
long as the separate circuit originates from the same
panelboard as the other lighting circuits and the branch
circuit is provided with a lock-on feature.
An important and often overlooked
requirement for unit equipment is the wiring method allowed
for the dc circuits supplying remote luminaires that obtain
emergency (battery) power from unit equipment but are not part
of the unit equipment. The dc circuits run to remote
luminaries supplied by the unit equipment must be installed in
a wiring method specified in Chapter 3. Flexible cord-and-plug
connections are permitted for the supply wiring for unit
equipment provided the cord length does not exceed 3 feet.
Calculating the correct capacity for
generator-type emergency systems involves verification of the
connected load and comparing it to the capacity of the
generator. (Remember to include all emergency loads, including
the fire pump load if one is provided). Section 700.5(B) has
additional information about the allowances for load shedding
and peak load shaving process.
When an emergency system has a generator
with a combustion engine as the prime mover, the capacity of
the fuel system is an important factor. Where internal
combustion engines are used as the prime mover, an on-site
fuel supply shall be provided with an on-premise fuel supply
sufficient for not less than 2 hours’ full-demand operation
of the system. Where the generator prime mover is fueled by a
public utility gas system it must not depend on that one fuel
supply alone. Where two fuel supplies are used, they must be
arranged for automatic transferring from one supply to the
other in the event of failure in one of the supply systems.
The primary focus is redundancy of the fuel supply to assure
reliability of the emergency system.
Rough-in Wiring
Inspection
Once the project is underway, inspections of the
field-installed electrical wiring and equipment are performed
at various stages of construction to verify compliance with
the code. There are a few key points for inspecting an
emergency system during the rough-in stages of a construction
project.
Before stepping onto the site, the
inspector must understand the single-line diagram and be able
to identify essential components of the emergency system and
the emergency distribution system. During an initial visit to
the jobsite, the field inspector has an obligation to verify
that the planned location of the emergency system source will
not be subject to adverse conditions such as flooding, icing
or fire. This important design consideration is required by
700.9(C). Note: During the plan review process there is
limited ability to verify the suitability of the source
location and/or the proper use of equipment. Although these
are considerations for the engineer or design professionals,
the field inspector always has the right to examine their
decision and to question prior approvals. Any questioning
usually is done in the plan review stages of a project. This
is just another of many good reasons for having electrical
plan review as part of any inspection team (see figure
1).
The rough inspection of any construction
project that has an emergency system should include the
awareness that emergency system conductors, generally, are not
permitted to be installed in the same raceways or enclosures
with the normal circuit conductors. There are four conditions
where emergency system wiring and normal wiring are permitted
to occupy the same enclosures, such as transfer equipment,
exit or emergency luminaries, etc., as indicated in
700.9(B)(1) through (4) [see figure
2]. This requirement is to minimize the possibility of
failures in the normal system circuits causing damage to the
emergency system circuits. It should be understood that
emergency systems are required to operate in the event of a
premise crisis situation, which often includes the loss of
normal power. Failure of the emergency system during these
conditions is a safety issue and can be avoided by compliance
with the Code. Good emergency system designs strive for
redundancy on many levels, often exceeding the minimum
requirements of the applicable codes and standards.
Emergency System
Equipment Approvals
Product listing is the basis for the final installation
approval. Sometimes the Code specifically requires
certain types of equipment to be listed, but in the case of
equipment used in constructing an emergency system, approval
is required. The general requirement in Section 700.3 is that
all equipment used in an emergency system be approved; and approved is defined in the NEC as "acceptable to the
authority having jurisdiction." This is a valuable and
effective tool for the inspectors who are charged with the
task of approving electrical installations and systems. While
electrical equipment may be manufactured to product safety
standards and be listed, this section mandates the inspection
and approval of the entire emergency system. Listed equipment
has been evaluated for electrical safety and is identified for
a specific use, so the inspector must verify that the
equipment is installed and used in accordance with those
installation instructions.
Inspectors should verify that transfer
equipment is of the automatic type and is identified for use
on emergency systems in accordance with 700.6. Identified is defined in the Code as "recognizable as
suitable for the specific purpose, function, use, environment,
application, and so forth, where described in a particular Code requirement" (see figure
3). Generally, the means of determining suitability of
equipment for specific purposes, environments, uses or other
applications includes product evaluation by a qualified
testing laboratory (listing and labeling), an inspection
agency, or other organizations concerned with
product evaluations. Field evaluation services are also
available to assist inspectors in the approval process.
Field Marking and
Identification Requirements
Equipment and enclosures used in emergency systems are
required to be permanently marked so that they can be readily
identified as components of the emergency system in accordance
with 700.9(A) [see figures 4 and 5]. This
verification often occurs as equipment and wiring are being
installed during the early phases of a project, but much of
the equipment marking is also verified during the final
inspection process. One example of readily identifiable as a component of an emergency system is substantial labeling
that states the word "emergency" in the text of the
label such as "Emergency Transfer Switch." Marking a
junction box cover for an emergency system branch circuit with
"E-1, 3, 5" is an example of noncompliance with this
requirement. This marking is not readily identifiable. The
local authority having jurisdiction has the final word as to
what is acceptable and meets the requirements of permanent and readily identifiable as used in that Code rule.
Another field-marking requirement in
700.8(A) requires a sign to be placed at the service-entrance
equipment that indicates the type and location of the on-site
standby system source. Once again, the local authority having
jurisdiction has the final word as to what is acceptable and
meets the requirement (see photo
2).
Several additional rules in Article 700
pertain to emergency system installations; we have highlighted
only a few of the key areas above. Now, let’s place some
specific emphasis in an essential part of inspecting
electrical emergency systems: the witness test. Section
700.4(A) requires the AHJ to conduct or witness a performance
test of the emergency system operation. This involves
simulation of normal power failure, usually by operating the
service disconnect to the open or off position. Witness
testing of unit equipment used for the emergency system should
be done by de-energizing the local area lighting circuits.
This ensures that the unit equipment is properly connected to
the lighting circuit in the area as required by 700.12(F).
Emergency System
Witness Testing
The National Electrical Code provides primarily
prescriptive rules and little in the way of performance or
systems tests; however, a few performance tests are required.
Two that come to mind immediately are the performance testing
requirements for ground-fault protection systems as specified
in Sections 230.95(C) and 517.17(C) and (D). These required
tests are essentially are for equipment only—to ensure that
the equipment functions properly under ground-fault
conditions. In health care facilities, the performance testing
for GFP equipment required by 517.17(C) and (D) not only
demonstrates successful operation but also selectivity between
the service and feeder ground-fault protection equipment.
The Code is specific in 700.4(A) in
requiring the AHJ to conduct or witness a test of the complete
emergency system upon installation. This is an acceptance
performance test of a complete system, not just the equipment,
and must simulate power failure and verify that the systems
function as designed.
The extent of the witness test inspection
is related to the complexity of the particular emergency
system. Where unit equipment is involved, the test can be
accomplished by switching the circuits supplying each area and
verifying operation of the unit equipment and the minimum
number of foot candles at the floor in the egress paths and at
exits.
During the scheduled outage of the witness
test, Code enforcement officials from various
disciplines—such as the fire department, building inspector
and mechanical inspector—can verify functions such as fire
dampers, smoke evacuation and other systems connected to the
emergency source. If only one inspector is responsible for all
of aspects of the system, the witness testing can take an
extended period of time.
When more complex emergency systems are
supplied by generators, the witness testing of the system
becomes more extensive, and verification of the fuel source is
required. First, the normal power source is removed to verify
that the generator starts and the load is transferred to the
generator. All of this must happen within ten seconds of the
loss of the normal supply power system. The emergency power
must be connected to the occupancy within ten seconds of a
power loss as required by 700.12, and can only be verified
during a true witness test.
I recently had a conversation with an
electrical inspector that included a discussion about a fairly
large medical center that was nearing completion and needed a
certificate of occupancy (C of O) for the project. The
emergency system failed the witness test when the prime mover
refused to start and, obviously, failed to power any of the
emergency loads within ten seconds, or even at all. The
electrical inspector said, "I’m sure glad we require
witness testing of the emergency systems, especially with all
the liabilities connected with the responsibilities of Code enforcement officials." This inspector did his job by
requiring the witness test and all parties concerned were
reminded of the importance of conducting an operation test on
the emergency system.
Specifically witnessing the emergency
systems operation is an essential element of the inspection
process and definitely qualifies as an electrical inspection
hot spot.
Summary
A thorough inspection of an emergency electrical system must
include the rough wiring of the system at various stages of
construction and a witness test of the system performing its
intended function. Since considerable investment and time goes
into designing and installing an adequate and reliable
emergency standby power system, testing protects both the
investment and the expected performance.
An essential element of the approval
process involves performance testing the system under full
load conditions. This test requires simulating a failure of
the normal supply power system to the building or structure.
It is not the responsibility of the AHJ to perform the test by
actually operating the equipment; rather, this task falls
under the scope of the installer or owner. The AHJ must
witness the test and generally will document the results.
Methods of documentation will vary from jurisdiction to
jurisdiction.
Periodic testing of the system is also
required in accordance with 700.4(B). Documented incidents
have demonstrated that emergency systems that are not
performance tested or not tested on a regular basis after the
initial installation, often fail to operate when called upon.
Many jurisdictions have various remedies and interesting
solutions for meeting this Code rule.
Approval of the electrical emergency system
includes conducting or witnessing the system function as
intended, and is not an option; it is a Code requirement. As always, it is best to consult your local AHJ
for any additional requirements regarding emergency system
witness tests or the Code.
Michael J. Johnston is IAEI’s
director of education and an IAEI principal member on
CMP-5. Johnston was formerly employed as an electrical
field inspections supervisor for the city of Phoenix,
Arizona. He is fully certified in many areas. He is a
member of the IBEW. He achieved both journeyman E-2 and
master electrician E-1 licenses in the state of
Connecticut. Additionally, he holds all IAEI
certifications. He also holds ICC Electrical Inspections
Certification. He is a member of the UL Electrical
Council. |
