After writing a few articles on this subject, I received numerous comments and questions from the readers. These questions and comments demonstrate that the clarity on this subject is far from being complete. Below are eight examples of such questions (with the follow-up answers).

Q. When is the emergency generator required to be used in a building?

A. Article 3.2.7.9. of the National Building Code of Canada (NBC) mandates use of an emergency generator as the source of the emergency power supply for the following life safety equipment:

3.2.7.9. Emergency Power for Building Services

1) An emergency power supply capable of operating under a full load for not less than 2 h shall be provided by an emergency generator for

a) every elevator serving storeys above the first storey in a building that is more than 36 m high measured between grade and the floor level of the top storey and every elevator for firefighters in conformance with Sentence (2),

b) water supply for firefighting in conformance with Article 3.2.5.7., if the supply is dependent on electrical power supplied to the building,

c) fans and other electrical equipment that are installed to maintain the air quality specified in Articles 3.2.6.2. and 3.3.3.6.,

d) fans required for venting by Article 3.2.6.6., and

e) fans required by Clause 3.2.8.4.(1)(c) and Article 3.2.8.7. in buildings within the scope of Subsection 3.2.6.

It means that the emergency generator must be installed in every high building as the required emergency power supply source for smoke control and smoke venting fans and dampers—for the equipment intended to provide pressurization of vestibules constructed for protection of exit opening into an interconnected floor space (into an atrium) and in every high building—for a mechanical exhaust system intended to remove air from an interconnected floor space (from an atrium) at a rate of four air changes per hour.

It also means that the emergency generator must be installed in every high building for every elevator designated as a “firefighter” elevator, and in every high building exceeding 36 meters high, measured between grade and the floor level of the top story.

It means that the emergency generator must be provided in every building of detention, treatment, or care occupancy (regardless of whether it is a high building or not), where area of refuge is created adjacent to the compartments containing rooms such as operating rooms, recovery rooms, delivery rooms, and intensive care units, from which it is impracticable to move patients in an emergency—to provide an emergency power supply source to the mechanical air supply to such area of refuge. And, of course, the emergency generator must be provided in every building (regardless of whether it is a high building or not) for firefighting water supply—to provide emergency power supply to the fire pump if the water supply is dependent on electrical power supplied to the building (i.e. if the electrically connected fire pump is required for effective operation of a sprinkler or standpipe system).

Q. Why must the emergency generator comply with the CSA Standard C282?

A. Article 3.2.7.5. of the NBC states the following:

3.2.7.5. Emergency Power Supply Installation

1) Except as required by Articles 3.2.7.6. and 3.2.7.7., an emergency electrical power supply system shall be installed in conformance with CSA C282, “Emergency Electrical Power Supply for Buildings.” (See Sentence 3.2.7.8.(1) for emergency electrical power supply for voice communication systems.)

In addition, Rule 42-202(3) of the Canadian Electrical Code, Part I (CE Code) provides the following requirement:

46-202 Types of emergency power supply

3) Where a generator is used, it shall be

a) of sufficient capacity to carry the load;

b) arranged to start automatically without failure and without undue delay upon the failure of the normal power supply to any transfer switch connected to the generator; and

c) in conformance with CSA C282.

It should be noted that the scope of CSA Standard C282 offers the following clarification on application of this Standard:

1 Scope

1.1

This Standard applies to the design, installation, operation, maintenance, and testing of emergency generators and associated equipment for providing an emergency electrical power supply to electrical loads

a) in buildings and facilities when the normal power supply fails and an emergency electrical power supply is required by the National Building Code of Canada (NBCC); and

b) of essential electrical systems, where emergency generators are intended for use in health care facilities (HCFs) in accordance with Clause 6 of CSA Z32.

Notes:

1) For guidelines on emergency electrical power supply for life-support equipment, see Annex A.

2) In this Standard, the term “building” also includes facilities.

3) Normative provisions of this Standard are not limited to the installations where an emergency generator is used as the NBCC required emergency power supply source to the “life safety equipment.”

4) For guidelines on the use of emergency electrical power supply equipment for purposes beyond the provisions of Clause 1.1, see Annex D.

5) It is intended by the scope of this Standard that equipment other than “life safety equipment” could be connected to the emergency generator (see Clause 6.4.1).

6) For electrical power supply systems designed and installed to operate for purposes other than those specified in Clauses 1.1, the electrical power supply system should meet the requirements of this Standard, where practical, and in conjunction with the guidelines of Annex E of this Standard.

This means that it is expected that not only the NBC-required emergency generators, but also the generators used for a standby or backup power supply (when the emergency power supply by a generator is not specifically mandated by the NBC) should be installed and operated in accordance with C282.

This approach is consistent with the NBC Appendix A Notes on fire protection, which state the following:

Notes to Part 3 on Fire Protection

The provisions in this Part for fire protection features installed in buildings are intended to provide a minimum acceptable level of public safety. It is intended that all fire protection features of a building, whether required or not, will be designed in conformance with good fire protection engineering practice and will meet the appropriate installation requirements in relevant standards. Good design is necessary to ensure that the level of public safety established by the Code requirements will not be reduced by a voluntary installation.

Q. Is the emergency generator required to provide an emergency power supply for a fire alarm system or for emergency lighting and electrically connected exit signs in the event of a failure of the normal power supply?

A. The NBC does not specifically mandate use of the emergency generator—to provide emergency power supply for emergency lighting and for a fire alarm system. It allows use of batteries or generators for this purpose (see below):

3.2.7.4. Emergency Power for Lighting

1) An emergency power supply shall be

a) provided to maintain the emergency lighting required by this Subsection from a power source such as batteries or generators that will continue to supply power in the event that the regular power supply to the building is interrupted.

3.2.7.8. Emergency Power for Fire Alarm Systems

1) Fire alarm systems, including those incorporating a voice communication system, shall be provided with an emergency power supply conforming to Sentences (2), (3) and (4).

2) The emergency power supply required by Sentence (1) shall be supplied from

a) a generator,

b) batteries, or

c) a combination thereof.

However, when a design decision is made—to utilize the generator as the emergency power supply source for emergency lighting and fire alarm system—installation of such emergency generator must comply with the applicable provisions of the NBC, CE Code and C282.

Q. Is a dedicated service room for a generator required in a high building only?

A. If a generator is required in accordance with Article 3.2.7.9. of the NBC—(regardless of whether it is a high building or not) or whether it is used as an optional emergency power supply source for the emergency lighting or fire alarm system as described in Articles 3.2.7.4. and 3.2.7.8. of the NBC above—then the emergency power supply system, the generator, and auxiliary equipment described in Clause 5.1 of C282 (see below) must be located in a dedicated service room conforming to Article 3.6.2.8. of the NBC as follows:

3.6.2.8. Emergency Power Installations

1) Where a generator intended to supply emergency power for lighting, fire safety and life safety systems is located in a building, except where such building is used solely for the purpose of housing the generator and its ancillary equipment, it shall be located in a room that

a) is separated from the remainder of the building by a fire separation having a fire-resistance rating not less than 2 h, and

b) contains only the generating set and equipment related to the emergency power supply system.

Clause 5.1 of the CSA Standard C282 clarifies the extent of “equipment related to the emergency power supply system“ as follows:

5.1

The emergency electrical power supply system shall consist of all of the equipment and systems necessary to supply reliable electrical power, including the following:

a) the engine generator set, which can include an auxiliary supply tank;

b) the fuel supply system, including tanks and piping as described in Clause 7.3;

c) automatic transfer switches and all associated wiring;

d) the emergency generator ventilation and cooling system;

e) wiring and all electrical components between an emergency generator and the emergency supply terminals of transfer switches specified in Clause 9; and

f) the exhaust silencer and piping to outdoors.

It means that if an emergency generator supplies loads of life safety systems and loads which are not defined by Section 46 of the CE Code as life safety systems, only automatic transfer switches related to the life safety systems could be located in two-hour rated, dedicated generator service rooms. But the automatic transfer switches used in conjunction with non-life safety equipment are not permitted to be installed in these generator rooms.

It should be noted that transfer switches used for feeders supplying life safety systems, including fire pumps, could be installed outside of this dedicated two-hour rated generator service room. However, in such, latter cases, life safety transfer switches, or other emergency power supply or emergency distribution life safety equipment must be located in a one-hour rated service room, as required by Article 3.6.2.1. of the NBC.

Application and installation requirements for emergency generators

Q. Are panels, transformers, or MCCs related to the life safety systems allowed to be located in a dedicated generator service room required by Article 3.6.2.8. of the NBC, as described above?

A. Only equipment that directly relates to the components listed in Clause 5.1 of C282 are permitted to be located in the two-hour rated generator service room, as only such equipment represents the emergency power supply system. All other types of life safety distribution or utilization equipment is not allowed to be located in this dedicated generator service room, because the equipment is not a part of the emergency power supply system.

Q. Is life safety equipment allowed to be located in the same service room as non-life safety equipment?

A. The NBC does not place any restriction on location of the life safety equipment and non-life safety equipment in the same service room. The NBC only mandates that the service room which contains life safety equipment (distribution or utilization) must have a fire resistance rating of not less than one hour. The NBC even allows use of a common service room for electrical and mechanical equipment (see Article 3.6.2.3. below):

3.6.2.3. Service Equipment

1) A service room containing space heating, space cooling and service water heating appliances is permitted to contain other service equipment such as electrical service equipment.

Q. Does Rule 46-204 mandate fire protection of conductors between an emergency generator and the emergency power supply equipment be located outside the generator room, even if a building is a non-high-rise building, has no fire pump, and the generator is only used as the emergency power supply source for emergency lighting?

A. Scope of Section 46 states that this section applies to the life safety systems and emergency systems which are required by the NBC.

Thus, when a generator is required by Article 3.2.7.9. of the NBC, protection of conductors between the generator and such components of the emergency power supply system which could be installed outside a two-hour rated generator room (i.e. a ATS) would have to be protected against exposure to fire in conformance with Article 3.2.7.10. of the NBC.

If a generator is not required by Article 3.2.7.9. of the NBC but is used in accordance with Article 3.2.7.4. of the NBC as an optional emergency power supply source for emergency lighting, and the installation is not in a high building, then provisions of Rule 46-204 would not apply. An example would be when this type of emergency generator is located in a two-hour rated service room, and the ATS for life safety equipment is located in another one-hour rated service room, as fire protection of conductors between this generator and emergency lighting would not be required by Sentence 3.2.7.10.(1) of the NBC.

Q. Under what conditions/requirements would Article 3.2.7.10. of the NBC for fire protection of electrical conductors apply?

A. Sentence 3.2.7.10.(1) of the NBC states the following:

3.2.7.10. Protection of Electrical Conductors

1) The protection of electrical and emergency conductors referred to in Clauses (a) to (c) shall conform to the requirements stated in Sentences (2) to (11):

a) electrical conductors located within buildings identified in Article 3.2.6.1. serving

i) fire alarms,

ii) emergency lighting, or

iii) emergency equipment within the scope of Articles 3.2.6.2. to 3.2.6.8.,

b) emergency conductors serving fire pumps required to be installed under Article 3.2.5.18., and

c) electrical conductors serving mechanical systems serving

i) areas of refuge identified in Clause 3.3.3.6.(1)(b), or

ii) contained use areas identified in Clauses 3.3.3.7.(4)(a) and (b).

Sentence 3.2.7.10.(1) above is quite clear that the emergency conductors supplying certain equipment in high buildings only (i.e. fire alarm systems, emergency lighting, elevators, smoke control, and smoke venting equipment) is required to be protected against exposure to fire. This NBC Sentence also clarifies that when any building (regardless of whether it is a high building or not) is provided with the electrically connected fire pump, or if any building (regardless of whether it is a high building or not) is provided with mechanical systems in areas of refuge conforming to Clause 3.3.3.6.(1)(b) or in contained use areas conforming to Clause 3.3.3.7.(4)(a) to (b), then fire protection of conductors is required.

Sentences (2) and (3) of this NBC Article describe the methods under which such fire protection could be accomplished, and Sentences (5) to (11) explain the extent of such fire protection, depending on the location of the emergency conductors and on the location of the equipment served by these conductors.

Hopefully, the eight answers above to the posted questions will provide necessary clarification on this issue. However, as usual, the local authorities having jurisdiction should be contacted on any concerns regarding specific installation conditions.

Ark Tsisserev is president of EFS Engineering Solutions, an electrical and fire safety consulting company, and is a registered professional engineer with a master’s degree in Electrical Engineering. Prior to becoming a consultant, Ark was the Chief Electrical Inspector for the City of Vancouver. He is the immediate past chair of the CSA TC for the CE Code, Part I and for the CSA Strategic Steering Committee for the Requirements of Electrical Safety. Ark also represents the CE Code Committee on the CMP-1 of the National Electrical Code. Ark can be reached by e-mail at: ark.tsisserev@efsengineering.ca His company web site is www.efsengineering.ca

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