Emergency power for Fire Safety Systems
For many years there
were no accepted standards for the design of emergency and standby power
systems, even though these systems have been in use since World War II.
Recognizing this need, NFPA formed the Technical Committee on
Emergency Power Supplies in 1976. Although the committee developed a report
proposing adoption of NFPA 110: Standard for Emergency and Standby Power
Systems, it wasn’t until the 1984 NFPA Fall Meeting that the document was
adopted as a standard and became the 1985 edition.
Today emergency and
standby systems are used to provide backup power for building systems to
provide assurance that life safety systems and critical equipment can maintain
their operation during a power outage. The use of these systems almost comes as
second nature when designing large, complex facilities. Yet, how well do you
know the specific requirements for these systems? Questions we must consider
include:
- When is emergency and standby
power required?
- What are the requirements for
the design of an emergency and standby power system?
- What building fire safety
systems need to be provided with emergency and standby power?
What
is it?
In general terms, as
defined in NFPA 70: National Electrical Code (NEC), there are three types of
emergency and standby power: emergency power, legally required standby power,
and optional standby power. Emergency power is required by codes for systems
whose operations are essential for safety to human life. Legally required
standby power is required by codes for illumination and power equipment that is
not categorized as requiring emergency power, but whose failure could create
hazards or hamper rescue or firefighting operations. Optional standby power is
not required by code and provides equipment whose failure will not impact life
safety.
When
is it required?
The basic requirements
for where the provision of an emergency and standby power is necessary come
from the building and fire codes. Whether the local jurisdiction follows NFPA
5000: Building Construction and Safety Code, NFPA 1: Fire Code, NFPA 101: Life
Safety Code, the International Building Code (IBC), or the International Fire
Code (IFC), the requirements are reasonably consistent. Each of these codes
broadly defines the fire, life safety, and critical operations power systems
(COPS) that require emergency and standby power systems. While the building
codes primarily deal with requirements for new or remodeled buildings, the
requirements of the fire codes and NFPA 101 may also apply to existing
buildings, as such there may be retroactive emergency and standby power issues
to be addressed under these documents.
Specific requirements
for emergency and standby power will vary based on building occupancy type,
facility use, and critical function. With these parameters, the need for
emergency or standby power is determined and described in either a building or
fire code. For example, the 2009 IBC requires emergency power for:
- Emergency voice/alarm
communications systems in Group A assembly occupancies
- Exit signs
- Means of egress illumination
- Fire alarms and exhaust
ventilation in HPM facilities
- Power operated doors in
detention facilities.
- Some of the places where the
IBC requires standby power include:
- Smoke control systems
- Emergency voice/alarm systems
in large covered mall buildings
- Accessible means of egress
elevators and platform lifts
- Horizontal sliding doors used
for egress
- Membrane structure auxiliary
inflation systems
- Mechanical vestibule and stair
shaft ventilation systems and fire detection systems for smokeproof
enclosures.
While the 2009 edition of the IBC and NFPA 5000 have similar
requirements for emergency and standby power (such as high-rise buildings and
healthcare facilities) there are some requirements that differ slightly. Some
of these differences include:
- NFPA 5000 identifies elevators
in towers that are used as a second means of egress, in such buildings,
the elevator equipment, communications, machine room cooling, and
controller cooling all must be provided with normal and standby power
- Also in NFPA 5000, in buildings
more than 120 ft in height, a first responders use elevator must be
provided that is served by standby power.
NFPA
101 and NFPA 99
NFPA 101 and NFPA 99 are
two principal documents widely used in the design of healthcare facilities.
While NFPA 101 covers all classifications of building occupancy use, NFPA 99
specifically addresses healthcare facilities.
The 2009 edition of NFPA
101 presents basic requirements for emergency lighting in Section 7.9.
Emergency power systems for emergency lighting are to comply with the 2005
edition of NFPA 110. Stored electrical energy systems are required to comply
with the 2005 edition of NFPA 111: Standard on Stored Electrical Energy
Emergency and Standby Power Systems. Each of the occupancy chapters identifies
whether emergency lighting is required in that occupancy.
High-rise building
requirements in NFPA 101 are presented in Section 11.8. Among the requirements
are the need for the installation of automatic suppression, fire detection, alarm,
and communications systems. To provide assurance that these systems will be
available in a fire emergency, emergency and standby power are required. The
system is to be in accordance with NFPA 110 to serve the electric fire pumps,
emergency command center equipment and lighting, elevators, mechanical
equipment for smokeproof enclosures, and mechanical equipment serving the smoke
control systems.
While emergency and
standby power requirements are found in several other occupancy use areas, the
healthcare occupancies have the most detailed requirements. NFPA 101 provides
the overall requirements where fire detection, alarm, and suppression systems
are required, where emergency lighting is required, and other basic fire and
life safety needs. However, when it gets to the details of what specific
systems need to be served by what level of power reliability, NFPA 99 takes the
lead.
The 2009 edition of NFPA
99 identifies three classifications of essential electrical equipment
categories based on the level of criticality of the systems served:
- Life safety branch
- Critical branch
- Equipment system.
The life safety branch
is defined as:
A subsystem of the
emergency system consisting of feeders and branch circuits, meeting the
requirements of Article 700, of NFPA 70 and intended to provide adequate power
needs to ensure safety to patients and personnel, and that is automatically
connected to alternate power sources during interruption of the normal power
source.
The life safety branch
of the emergency system provides the emergency power for:
- Illumination of the means of
egress
- Lighting of the exit and
directional signage
- Fire detection and alarm system
- Non-flammable medical gas
system and vacuum systems alarms
- Hospital emergency
communication systems
- Task lighting, battery charger,
and selected receptacles in generator set location
- Elevator control,
communication, and lighting
- Automatic operating egress
doors
- Auxiliary fire alarm system
functions.
The critical branch is
defined as:
A subsystem of the
emergency system consisting of feeders and branch circuits supplying energy to
task illumination, special power circuits, and selected receptacles serving
areas and functions related to patient care and that are connected to alternate
power sources by one or more transfer switches during interruption of normal
power source.
The critical branch may
be divided into multiple branches. The critical branch is dedicated for use in
powering specific circuits related to patient care and includes the following:
- Task illumination, selected
receptacles, and fixed equipment in critical care areas using
anesthetizing gas
- Isolated power systems in
special environments
- Task illumination and selected
receptacles in patient care, medication preparation, pharmacy dispensing,
and nurses stations
- Task illumination and
receptacles in specialized patient care areas
- Nurse call systems
- Bone, blood, and tissue banks
- Other selected illumination and
receptacles.
In order to be able to
meet the time requirements of these two essential equipment categories, it is
typically necessary to have some combination of stored power and generator
power solution.
The equipment system is
defined as:
A system of circuits and
equipment arranged for delayed, automatic, or manual connection to the
alternate power source and that serves primarily 3-phase power equipment.
The equipment system is
allowed to serve the following delayed-automatic or manual connection to the
alternate power source:
- Heating equipment serving
various treatment spaces
- Patient rooms under specific
conditions
- Certain elevators
- HVAC systems for select areas
- Hyperbaric and hypobaric
facilities
- Autoclaving equipment
- Controls for the above listed
equipment
- Other selected equipment.
Fire
codes
While the fire codes are
companion documents to the building codes, remember that the fire codes are an
occupancy and use enforcement document, not a construction enforcement document
per se. As such, it is unusual to find requirements in a fire code that would
require a new system to be installed in an existing building under a fire code.
The typical requirements of a fire code will be to maintain the systems in the
building that were required under the version of the code followed when the
building was first built. Exceptions to this distinction would include:
- Substantial changes made in
building construction, occupancy, or use after the adoption of the code
- Existing buildings, structures
or operations that were not legally in existence prior to adoption of the
code
- Specific hazardous conditions
when specifically addressed by the code
- Existing facilities that have
been identified as constituting a distinct hazard to life or property.
With this basic
differentiation, the following are some of the primary fire code implications
for emergency and standby power.
Since the primary focus
of both NFPA 1 and the IFC is on assuring that fire protection and life safety
equipment is properly maintained, it should come as no surprise that both
documents require building owners to keep up to date records on inspection and
maintenance of their emergency and standby power.
In Section 604 of the
2009 IFC, requirements for emergency power systems are delineated. The section
is consistent with the requirements of Section 2702 of the IBC and requires
compliance with the 2005 NFPA 110 or the 2005 NFPA 111 where emergency and
standby power systems are to be installed. The required locations and systems
include emergency voice and alarm communications systems for assembly
occupancies, smoke control systems, exit signs, means of egress illumination,
accessible means of egress elevators, horizontal sliding doors, membrane
structures, semiconductor manufacturing facilities, and several other
facilities. It further requires stationary emergency and standby power systems
to be in compliance with the 2004 edition of UL 2200: Standard for Stationary
Engine Generator Assemblies.
In the 2009 NFPA 1,
Section 11.7.3 covers emergency and standby power requirements. Section
11.7.3.1 requires compliance with the 2005 NFPA 110 for stationary generators while
Section 11.7.4 requires compliance with the 2001 NFPA 111 for stored electrical
energy and standby power systems. Emergency lighting requirements are in
Section 14.13. This section refers to NFPA 101 for specific facilities
requirements.
Design
requirements
Once the building code
establishes the need for an emergency and standby power system, their design
requirements are found in installation standards, such as the 2008 NEC. Article
700 of NFPA 70 establishes the ground rules for emergency system’s components,
equipment and their installation. The article addresses basic requirements for
these systems, defines circuit wiring, sources of power, and emergency system
circuits. In accordance with Section 700.12, the emergency lighting and
emergency power must be available within 10 seconds of a failure of the normal
building power supply. This can be accomplished by:
- A storage battery that can
maintain the load for a minimum of 1.5 hours without a voltage drop below
87.5% of normal
- Generator set that automatically
starts on failure of normal service that has an automatic transfer switch
for all required circuits (if the generator requires greater than 10
seconds to develop power, an auxiliary power supply must be provided until
the generator can pick up the load)
- A UPS that meets the
requirements of one of the two means described above
- Separate service (where
approved by the authority having jurisdiction)
- Fuel cell with a rating and
capacity to supply and maintain the total load for not less than two hours
of full demand operation.
Similarly, Article 701
of the 2008 NEC covers installation requirements for legally required standby
systems. Article 702 of the NEC covers these requirements for optional standby
systems.
Emergency and standby
power systems have different requirements for the time required to transfer the
load. Emergency and legally required standby systems must have automatic
transfer switches. As previously noted, emergency system loads must be
transferred within 10 seconds after the failure of the primary power supply.
Legally required standby system loads must be transferred within 60 seconds
after the failure of the primary power supply. Optional standby systems are not
required, so there is no maximum transfer time. In addition, an optional standby
system is permitted to have a manual transfer switch.
Emergency systems also
have requirements for separation from nonemergency circuits. This requirement
is intended to prevent simultaneous impairment of the normal and emergency
systems. Legally required and optional standby systems can be mingled with
wiring for other power systems.
NFPA 110 provides the
following definitions:
- Emergency Power Supply (EPS) –
The source of electric power of the required capacity and quality for an
emergency power supply system (EPSS).
- Emergency Power Supply System –
A complete functioning EPS system coupled to a system of conductors,
disconnecting means and overcurrent protective devices, transfer switches,
and all control, supervisory, and support devices up to and including the
load terminals of the transfer equipment needed for the system to operate
as a safe and reliable source of electric power.
NFPA 111 provides the
following additional definitions:
- Stored Emergency Power Supply
System – A system consisting of a UPS, or a motor generator, powered by a
stored electrical energy source, together with a transfer switch designed
to monitor preferred and alternate load power source and provide desired
switching of the load, and all necessary control equipment to make the
system functional.
- UPS – A system consisting of a
stored energy source, designed to continuously provide a clean,
conditioned sinusoidal wave of power under normal conditions and for a
finite period of time upon loss of the primary power source.
In NFPA 110, emergency
power supply systems (EPSS) are assigned a class by minimum time (in hours) the
EPSS is designed to operate at its rated load without being refueled or
recharged. In addition to the class, they are further identified by type that
defines the maximum time in seconds the EPSS will permit the load terminals of
the transfer switch to be without acceptable power.
In NFPA 111, stored
emergency power supply systems (SEPSS) are rated by type, class, category, and
level. The type defines the maximum time in seconds the SEPSS will permit the
load terminals of the transfer switch to be without acceptable power. The class
determines minimum time, in hours, the SEPSS is designed to operate at its
rated load without being refueled or recharged. There are two categories;
Category A is devices that receive their energy from the normal supply and
Category B is all other devices not in Category A and not specifically excluded
elsewhere in the standard. There are two SEPSS levels. Level 1 is where failure
of the SEPSS to operate could result in injury or loss of human life. Level 2
are where failure of the SEPPS is not as critical to human life and safety.
COPS
In the 2008 edition of
NFPA 70 a new Article 708: Critical Operations Power Systems was added to the
mix of emergency and standby power. COPS raises the bar for the reliability of
power systems well above previous versions of NFPA 70.
The article provides for
the protection of vital infrastructure facilities that, if destroyed, would
disrupt public health, safety, or national security. The intended application
would be for facilities such as communications centers, air traffic control
centers, hazardous materials handling, financial data processing,
transportation centers, and other at-risk structures. Potential exposures to
these facilities would include natural disasters, such as hurricanes and
tornados, and manmade disasters such as terrorist acts.
Reason
for COPS
For many years the NEC
has addressed the need for emergency power in buildings to assist in getting
people safely out of buildings. The focus on emergency power in assembly and
healthcare facilities in particular has enhanced the safety for high occupancy
facilities and in the facilities where the occupants may have limited ability
to be moved.
Over the past 20 years
we have witnessed many disasters including devastating wind storms, hurricanes,
and floods, many of which have caused loss of power to many of the key
emergency management operations. Such emergency management facilities need to
be operational in order to appropriately respond to these incidents. Other
recent events that have raised concern over reliability, operation, and
approach to building emergency and standby systems include the Sept. 11, 2001
attacks, threats of biological terrorist attacks, and threats of attacks on our
infrastructure.
COPS have been developed
to provide guidance on the design of power systems for facilities or parts of
facilities that require continuous operation for the reasons of public safety,
emergency management, national security, or business continuity. These
facilities may include:
- Air traffic control centers
- Chemical, petrochemical, and
hazardous material (including biohazard) handling facilities
- Communications centers,
telephone exchanges, cellular tower sites
- 911 call centers
- Central station service
facilities (fire and security system monitoring)
- Financial, banking, business
data processing facilities
- Hospitals and associated
support facilities
- Police, fire, civil defense
facilities including power for radio repeater operations
- Emergency evacuation centers
- Transportation infrastructure
–airports, rail stations, seaports
- Municipal infrastructure –water
and sewer treatment facilities
- Fuel supply pumping stations
(i.e. natural gas distribution and delivery infrastructure
- Offices and facilities deemed
critical to continuity of government
- Radio and television stations.
Similar to the approach
taken to Articles 700 and 701, the determination on where COPS is required is
from the authority having jurisdiction (AHJ) in the form of emergency
management directors, fire officials, police officials, building officials,
Federal Emergency Management Agency, and others.
In accordance with
Section 708.4, a risk assessment must be conducted for COPS to:
- Identify hazards (naturally
occurring and human caused)
- Determine the likelihood of
their occurrence
- Assess the vulnerability of the
power system to those hazards
- Evaluate the need for physical
security
- Develop a mitigation strategy.
The system is required
to be commissioned and periodically tested.
A facility with a COPS
is required to have a documented plan that considers emergency operations, and
response, recovery, and continuity of operations.
As our world continues
to change, the applications for emergency and standby power should be expected
to continue to play a key role in providing reliable power for our most
critical needs. The more we come to rely on consistent delivery of power to run
our world, the more we will need to rely on emergency and standby power.
Type of Equipment |
Maximum Time to
Energize Loads |
Minimum Run
Time(Duration) |
IBC/SBC Section |
IFC/SFC or NFPA Section |
Emergency Power Systems |
||||
Exit Signs |
10 Seconds |
2 Hours |
1013.6.3 |
604.2.9 High rises |
604.2.16 Underground buildings |
||||
1013.6.3 Exit signs |
||||
604.2.13 Temporary tents, canopies, Membrane
Structures |
||||
NFPA 70 |
||||
Exit illumination |
10 Seconds |
2 hours |
1008.3 |
1008.3 |
604.2.9 High-rises |
||||
604.2.16 Underground buildings |
||||
Any emergency voice/alarm communication including
area of refuge communications systems |
Per NFPA 72 |
24 hours; Battery:
4hours |
402.7.3, 402.7.4, and 907.5.2.2 Covered mall
buildings |
907.2.19 Covered mall buildings |
(barrier-free and
horizontal exits) |
|
(generator) |
403.4.8 and 907.5.2.2 High-rises |
604.2.9 High-rises |
405.8, and 907.5.2.2 Underground buildings |
604.2.16 Underground buildings |
|||
907.2.1, and 907.5.2.2 Assembly occupancies |
907.2.1.1 Assembly occupancies |
|||
NFPA 72 |
||||
907.2.11 Special amusement buildings |
||||
Fire detection and fire alarm |
Per NFPA 72 |
24 hours(battery)
and 4 hours (generator) |
403.4.8 High-rises |
604.2.9 High-rises |
405.8 Underground buildings |
604.2.16 Underground buildings |
|||
909.20.6.2 Smoke proof enclosures |
907.6.2 Power supply |
|||
907.2.11 Special amusement buildings |
||||
907 |
NFPA-72 |
|||
Smoke control systems in high-rise buildings, underground
buildings and covered mall buildings, and atriums, including energy
management systems if used for smoke control |
6o seconds |
2 hours |
403.4.8 High-rises |
909.11 Emergency power |
404.7 Atriums |
||||
405.8 Underground buildings |
||||
909.11 Smoke Control |
||||
Fire pumps in high-rise buildings and underground
buildings |
10 seconds |
8 hours (NFPA 20) |
403.4.8 High-rises |
604.2.9 High-rises and NFPA 20 |
405.8 Underground buildings |
604.2.16 Underground buildings |
|||
913.2 All Fire Pumps |
||||
Smoke-proof enclosures and elevator shaft
pressurization |
6o seconds for pressurizatio 1A |
4 hours |
403.4.8 High-rises 909 & 909.20.6.2 |
|
Any shaft exhaust fans required to run
continuously in lieu of dampers in high-rise and underground buildings |
6o seconds |
4 hours |
717.5.3 |
|
Fire service or occupant evacuation elevator car
operation in high-rise and underground buildings (including control system
,motor controller,operation control, signal equipment ,machine room
cooling/heating ,etc.) |
6o seconds |
4 hours |
3003, 3007 and 3008 |
604.2.9 High-rises |
Elevator car lighting and communications in
high-rise and underground buildings |
10 seconds |
4 hours |
3003, 3007 and 3008 |
604.2.9 High-rises |
6o4.2.16 Underground buildings |
||||
604.2.1 Elevators |
||||
604.2.9 High-rises |
||||
Lights, heating, and cooling for building fire
command center and mechanical equipment rooms equipment rooms serving the
fire command center |
6o seconds |
24 hours |
|
604.2.9 High-rises |
Power (other than lights, heating and cooling)
for building fire command center. |
60 |
4 |
|
|
Mechanical and electrical systems required by IFC
Chapter 27 (hazardous materials including UPS rooms) |
60 |
4 |
|
Chapter 27 |
Legally Required Standby-1 |
||||
Exhaust fans for any loading dock located
interior to a building |
6o Seconds |
4 hours |
|
|
Transformer vault ventilation equipment |
6o Seconds |
4 hours |
|
|
Heat tape for sprinkler lines and heating in
sprinkler riser rooms |
6o Seconds |
24 hours |
|
|
Fuel pump system for any legally required system |
6o Seconds |
4 hours |
|
|
Elevators used for accessible means ofegress (in
other than high-rise and underground buildings) |
6o Seconds |
2 hours |
|
|
Elevators (other than re service or occupant
evacuation elevators) in high-rise and underground buildings |
6o Seconds |
2 hours |
|
|
Any shaft exhaust fans required to run
continuously in lieu of dampers (in other than high-rise and underground
buildings) |
6o seconds |
4 hours |
717.5.3 |
|
Auxiliary inflation systems |
6o seconds |
2 hours |
3102.8.2 |
3103.10.4 |
Special purpose horizontal sliding, accordion or
folding doors |
6o seconds |
2 hours |
1010.1.4.3 |
1010.1.4.3 |
firefighter air replenishment systems (FARS) |
6o seconds |
2 hours |
919.7.2 |
919.7.2 |
Requirements covering the performance of emergency and standby power systems providing an alternate source of electrical power to loads in buildings and facilities in the event that the primary power source fails.
ReplyDeleteCovers installation, maintenance, operation, and testing requirements as they pertain to the performance of the emergency power supply system (EPSS).
Intent of standard is to achieve maximum system reliability. Requirements covering the performance of emergency and standby power systems providing an alternate source of electrical power to loads in buildings and facilities in the event that the primary power source fails.
Covers installation, maintenance, operation, and testing requirements as they pertain to the performance of the emergency power supply system (EPSS).