It is very encouraging to read numerous e-mails from the readers with feedback on my articles and with specific questions. I recently compiled ten new questions raised by the readers regarding the use of emergency generators, and in this article, I will post these questions and provide answers to them.
Question 1
Under what conditions an emergency generator is required?
Answer to question 1. Sentence 3.2.7.9.(1) of the National Building Code of Canada (NBC) specifically mandates the use of an emergency generator – to provide an alternate (emergency power supply source to the following electrically connected 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 in high buildings, such equipment as all elevators in buildings exceeding 36 m high, fire fighters’ elevators, smoke control, and smoke venting equipment and mechanical systems required in interconnected floor spaces (in atriums) must be provided with the emergency power supply delivered by an emergency generator, which must be capable of operating under a full load for not less than 2 h. It also means that in any building (hi-rise or low-rise, an emergency generator must be provided as an alternate source of power for an electrically connected fire pump.
Question 2
When is the optional use of an emergency generator recognized by the NBC?
Answer to question 2. While the NBC mandates the use of an emergency generator as the emergency power supply source for life safety equipment, described in answer to question 1, the NBC allows an option of an emergency generator or battery (or both) as an emergency power supply source for emergency lighting and fire alarm system (including voice communication), as follows:
“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.”
Question 3
What is the minimum quantity of fuel supply required for an emergency generator?
Answer to question 3. As indicated in answer to question 1, Article 3.2.7.9. of the NBC mandates that a required emergency generator must be capable of operating under a full load for not less than 2 h. In addition, CSA Standard C282, Emergency electrical power supply for buildings, has the following requirements regarding the minimum quantity of fuel supply for operating an engine:
“7.3 Fuel supply
7.3.1 Minimum quantity
A quantity of fuel sufficient for operating the engine under maximum site design load for at least 2 h shall be maintained on site at all times. The fuel supply shall be monitored with a local alarm indication and remote alarm annunciation in accordance with Table 1, and inspected in accordance with Table 2.
7.3.2 Health care facilities
In addition to Clause 7.3.1, where a generator set is required for emergency power supply to essential electrical systems in conformance with CSA Z32, a fuel supply shall be maintained on site at all times that is sufficient for operating the engine under full load for at least
a) 72 h for Class A HCF;
b) 24 h for Class B HCF; and
c) 24 h for Class C HCF.”
Readers are welcome to review the CSA standard Z32 regarding health care facility classifications.
Question 4
What constitutes “an emergency electrical power supply system”?
Answer to question 4. CSA standard C282 defines “emergency electrical power supply system” as follows:
“Emergency electrical power supply system — the local generation of electrical energy for supplying a load requiring emergency electrical power, as mandated by the NBCC, when the normal power supply fails.”
Clause 5.1 of C282 describes in detail all components comprising “an emergency electrical power supply system” as follows:
“5 Emergency electrical power supply system
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 lockable disconnecting means and overcurrent devices described in Clause 8.7.1;
c) the fuel supply system, including tanks and piping as described in Clause 7.3;
d) automatic transfer switches supplying the “essential electrical system” defined in Section 24 or the “life safety systems” defined in Section 46 of the Canadian Electrical Code, Part I;
e) the emergency generator ventilation and cooling system;
f) electrical components between an emergency generator and the transfer switches described in Item d), including but not limited to control and power wiring and overcurrent devices;
g) the overcurrent protective devices installed in the feeders supplying permanent or temporary load banks; and
h) the exhaust silencer and piping to outdoors.”
It means that such emergency equipment as distribution panelboards, transformers, disconnecting means, located on the load side of automatic transfer switches supplying life safety equipment listed in Section 46 of the Canadian Electrical Code, Part I (CE Code), is not a part of the “emergency electrical power supply system,” and it cannot be located in a service room, specifically dedicated to the “emergency electrical power supply system.”
Question 5
What are the requirements for the location of an emergency electrical power supply system?
Answer to question 5. Clause 5.2 of C282 and notes on this Clause offer the following provisions regarding the location of the emergency electrical power supply system:
“5.2 Unless otherwise specified by the authority having jurisdiction or as required by the NBCC, all of the components specified in Clause 5.1shall be separated from the remainder of the building by a fire separation with a fire-resistance rating of not less than 2 h.
Notes:
1) Not all of the components need be in the same room or other location in the building.
2) See Clause B.1 for commentary on this Clause.
3) The fire resistance rating for a room that contains any fuel storage, such as the auxiliary supply tank, might need to be increased in accordance with the requirements of CSA B139 and/or the authority having jurisdiction depending on the volumes of storage in each room.”
Provisions of this Clause are also confirmed by the following requirement of the NBC:
“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.”
It is interesting to note that while the emergency generator must be located in a 2 h rated service room, Note 1 on Clause 5.2 of C282 above clarifies that some components of the emergency electrical power supply system, such as automatic transfer switches, could be located in other service rooms. However, when such equipment is located in other service rooms, these service rooms must be separated from the remainder of the building by a fire separation having a fire-resistance rating not less than 1 h in accordance with Article 3.6.2.1. of the NBC.
Question 6
Are conductors interconnecting components of the emergency electrical power supply system, located outside the service room for the emergency electrical power supply system, required to be protected against exposure to fire?
Answer to question 6. Clause 5.3 of C282 mandates the following:
“5.3 When it is installed outside a service room, power and control wiring interconnecting the components specified in Clause 5.1 shall be protected against exposure to fire in accordance with the requirements of the NBCC, while ensuring continuous operation of the electrical circuit.”
Rule 46-204 of the CE Code also compliments clarification provided by Note on Clause 5.3 of C282 as follows:
“46-204 Protection of electrical conductors and cables
All power, control, and communication insulated conductors and cables between an emergency generator as described in Rule 46-202 3) and electrical equipment required to be installed as a part of the emergency power supply and located outside the generator room shall be protected against fire exposure to provide continued operation in compliance with the National Building Code of Canada.”
Question 7
What makes compliance with the CSA standard C282 mandatory?
Answer to question 7. When the NBC or CE Code is legally adopted for regulatory enforcement in a particular jurisdiction of Canada (in a province, territory or in a municipality governed by a municipal charter), compliance with these legally adopted Codes is compulsory, as these adopted Codes become part of local laws. Therefore, if compliance with C282 is mandated in the bodies of these legally adopted codes, then use of applicable provisions of C282 in electrical design, installation and inspection is also mandatory.
Compliance with C282 is mandated by Article 3.2.7.5 of the NBC and by Rule 46-202 of the CE Code as follows:
“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.”
“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.”
Question 8
Is an emergency generator allowed to be installed outdoors, and if it is, what are the requirements for the outdoor enclosure that houses the generator?
Answer to question 8. Clause 6.2.1 of C282 provides the following requirements:
“6.2.1 The emergency electrical supply system shall be located
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- a) in a separate service room or rooms in a building separated from the remainder of the building by a fire separation with a fire-resistance rating in accordance with the requirements of Clause 5.2; or
- b) in a separate service room or enclosure outside the building located in accordance with the NBCC. The enclosure shall provide the following protection and security for the emergency electrical supply system:
- i) The enclosure shall be structurally adequate to resist flood, snow, wind, and shall be vandal- proof. The enclosure shall be braced for seismic forces where required by NBCC.
- ii) The enclosure shall be weatherproof and insulated to achieve the ambient temperature requirement of Clause 6.8.1to maintain the system in an operable condition and prevent problems due to condensation and corrosion.
iii) The enclosure shall provide adequate clearances as specified in Clause 6.5.1.
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- iv) The enclosure structure shall have provision for electrical grounding in addition to the electrical equipment within the enclosure.
- v) The enclosure shall have provision for quick entry to authorized personnel.”
Question 9
Are there any specific provisions for location of an emergency generator intended to be used in a health care facility?
Answer to question 9. When an emergency generator is required by the health care facility administrator in accordance with Section 6 of Z32 – to provide an emergency power to the essential electrical system, defined and described in Section 24 of the CE Code and in Z32, then additional provisions of Clause 6.2.2 of C282 must be met as follows:
“6.2.2 Where an emergency electrical power supply system is required in conformance with CSA Z32, it shall be located within one storey of grade.”
However, if the emergency generator is not specifically mandated by the health care facility administrator – to provide emergency power supply to the essential electrical system in such health care facility, then compliance with Clause 6.2.2 or with Clause 7.3.2 of C282 above, is not warranted.
Question 10
What are the clearance requirements around an emergency generator?
Answer to question 10. General provisions for clearances around electrical equipment are mandated in Rule 2-308 of the CE Code.
Clause 6.5.1 of C282 provides the following requirements for clearances around an emergency generator:
“6.5.1 Clearances
6.5.1.1 The generator set and its controls shall be located in a way that provides adequate working space and ease of access for maintenance, repair, or removal, but not less than 1 m clearance except for the area of the exhaust air duct.
6.5.1.2 In Class A and Class B HCFs, the clearances defined in Clause 6.5.1.1shall be provided on all sides within the service room or within the enclosure.
6.5.1.3 If the required clearance cannot be provided within the enclosure for non-HCF and Class C HCF installations, the enclosure shall come complete with access doors on all sides of the unit where the clearance is required and shall be installed with not less than the required clearance defined in Clause 6.5.1.1 around the entire enclosure. Where the enclosure is not accessible by maintenance personnel standing on grade then either a permanent working platform shall be provided or the clearance shall be increased to allow for the required clearance plus space for a temporary working platform or ladder.
6.5.1.4 The clearance shall be maintained at all times, which includes keeping the areas around an enclosure free of obstructions such as ice and snow.”
Hopefully, answers provided to the posted ten questions from the readers, will further clarify this subject.
However, as usual, local AHJ should be always consulted regarding specifics of a particular design and installation.
