Protection of electrical equipment and electrical conductors against exposure to fire — are we consistent on this subject?

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This subject was raised by me previously in a number of articles during the past ten years, but I am receiving quite a few questions from the readers, as it appears that the requirements of the relevant Codes on this issue are not consistently applied by the designers and regulators. The reality is that the electrical designers must know the provisions of the Canadian Electrical Code and the National Building Code of Canada (NBCC); however, the electrical safety regulators or building inspection authorities may not necessarily be aware of such requirements in both Codes. So, for simplicity of dealing with this subject, let’s pose eight specific questions and provide the answers to these questions.

It should be noted that this discussion reflects practical questions presented by the readers as follows:

 

Does the CE Code mandate protection of electrical equipment against exposure to fire?

Answer: The CE Code provides such requirements in a number of Rules. For example Rule 26-012 states:

“26-012 Dielectric liquid-filled equipment —

Indoors (see Appendices B and G)

(1) Dielectric liquid-filled electrical equipment containing more than 23 L of liquid in one tank, or more than 69 L in a group of tanks, shall be located in an electrical equipment vault.

(2) Except as permitted in Subrule (4), dielectric liquid-filled electrical equipment containing 23 L of liquid or less in one tank, or 69 L or less in a group of tanks, shall be

(a)  installed in a service room conforming to the requirements of the National Building Code of Canada”;

While this requirement in Subrule 26-012(1) may not appear very transparent, Rule 26-354 clarifies it as follows:

“26-354 Electrical equipment vault construction (see Appendices B and G)

Every electrical equipment vault, including the doors, ventilation, and drainage, shall be constructed in accordance with the applicable requirements of the National Building Code of Canada.“

Rule 24-306 requires that loads of the essential electrical system in a health care facility must be provided by an emergency power supply source from an emergency generator and that such generator must be located in a fire-resistant enclosure or room:

“24-306 Emergency supply

An emergency supply shall be one or more generator sets driven by a prime mover that is located on the health care facility premises in a fire-resistant enclosure or room, in accordance with CSA Z32, and located such that the possibility of flooding and damage is minimized.“

Rule 46-202(3) states that an emergency generator used for life safety systems defined in Section 46, must comply with the CSA standard C282 as follows:

“46-202(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.“

The CE Code requirements quoted above are not very helpful to the users of the Electrical Code in order to determine the specifics of electrical equipment protection against exposure to fire. The CE Code users only become aware from these requirements that certain electrical equipment must be installed in an electrical equipment vault or in a service room, and that such vaults or service rooms must be constructed in accordance with the NBCC. The Code users also confirm from these requirements that an emergency generator must be installed in a fire-resistant room or enclosure, if the generator is intended to serve as the emergency power supply source to the loads of an essential electrical system in a health care facility, or must comply with C282, if it performs as an emergency generator –to supply life safety systems described in Section 46 with the emergency power.

So, let’s move to question 2, in order to clarify some of these requirements of the CE Code.

 

What are the NBCC fire protection requirements for an electrical equipment vault or electrical equipment room mandated by Rule 26-012 of the CE Code.

Answer:  In respect to the electrical equipment vault, the NBCC mandates the following fire resistance rating requirements:

“3.6.2.7. Electrical Equipment Vaults

1) An electrical equipment vault shall conform to Sentences (2) to (8) if it is required by

a) provincial or territorial regulations or municipal bylaws, or

b) CSA C22.1, “Canadian Electrical Code, Part I,” in the absence of the regulations or bylaws referred to in Clause (a).

 

2) An electrical equipment vault referred to in Sentence (1) shall be separated from the remainder of the building by a fire separation of solid masonry or concrete construction having a fire-resistance rating not less than

a) 3 h if the vault is not protected by an automatic fire extinguishing system, or

b) 2 h if the vault is protected by an automatic fire extinguishing system.“

Regarding the service room for such electrical equipment, the NBCC offers the following criteria:

“3.6.2.1.(6) Electrical equipment that is required to be located in a service room according to CSA C22.1, “Canadian Electrical Code, Part I,” shall be installed in a service room separated from the remainder of the building by a fire separation having a fire-resistance rating not less than 1 h.”

It should be noted that the references from the NBCC to the CE Code, Part I are actually directed to Rule 26-012 of the CE Code, as – except for location of an emergency generator (see answer to question 1 above)– no other rules of the CE Code specifically mandate installation of electrical equipment in a service room or in the electrical equipment vault.

 

What are the NBCC requirements for the service room containing an emergency generator?

Answer:  When the emergency generator is used to provide an alternate power supply to the life safety systems in any building or to the essential electrical system in a health care facility, location of this generator when it is installed in the building must comply with Article 3.6.2.8. of the NBCC 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.”

It should be noted that the NBCC does not provide any fire resistance rating requirements for an enclosure of the generator located outside the building. These requirements are listed in the CSA standard for emergency generators C282. However, Article 3.6.1.5. of the NBCC mandates a generic separation provisions for any fuel-fired appliance installed outside the building, as follows:

“3.6.1.5. Appliances Installed outside a Building

1) A fuel-fired appliance installed on the roof of a building or in another location outside the building shall be installed not less than

a) 1.2 m from a property line, measured horizontally, and

b) 3 m from an adjacent wall of the same building if that wall contains any opening within 3 storeys above and 5 m horizontally from the appliance, unless every opening within these limits is protected by

i) a closure having a fire-protection rating not less than 45 min determined in accordance with Article 3.1.8.4., or

ii) a wired glass assembly permitted for use in a vertical fire separation and described in D-2.3.15. in Appendix D.“

It should be also noted that Article 3.6.2.8. of the NBCC mandates that the service room containing an emergency generator must have a fire-resistance rating of not less than 2 h, and must contain only emergency power supply equipment. This requirement is attributed to a need to protect the emergency power supply equipment from a fire anywhere else in the building. It is interesting to note that such restrictive requirement of the NBCC is not extended to the service room that contains life safety equipment, as the NBCC does not specifically restrict other electrical equipment (i.e., equipment that does not have a life safety application) to be located in such service room.

Sentences 3.6.2.1.(7) and (8) of the NBCC simply clarify that the electrical equipment “essential to operation of fire safety systems in the building” must be located in the service room having a fire-resistance rating not less than 1 h.

 “3.6.2.1.(7)  Except as permitted by Sentence (8), in a storey that is not sprinklered throughout, a service room that contains service equipment other than that addressed by Sentences (1) to (6) shall be separated from the remainder of the building by a fire separation having a fire-resistance rating not less than 1 h.

3.6.2.1.(8) Where a service room contains a limited quantity of service equipment, and the service equipment neither constitutes a fire hazard nor is essential to the operation of fire safety systems in the building, the requirements for a fire separation shall not apply”.

 

What does CSA standard Z32 (mandated by Rule 24-306 of the CE Code) require in respect to protection of the emergency generator against exposure to fire?

Answer.  Actually, not much.  Z32 has only one requirement in Clause 6.7.1 on this subject.

“6.7.1 General

Emergency electrical power supply shall be provided by means of an emergency generator in conformance with CSA C282 as applicable for installation, operation, performance, testing, and maintenance of the emergency generator in HCFs.”

This fact leads us to the next question.

 

What does CSA standard C282 require in respect to protection of the emergency generator against exposure to fire?

Answer. C282 provides the following requirements in this regard:

“5.2

Unless otherwise specified by the authority having jurisdiction or as required by the NBCC, all of the components specified in Clause 5.1 shall 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.

 

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.

Note: See Clause B.2 for commentary on this Clause”.

As it could be seen from Clause 5.2 of C282, this standard is consistent with the NBCC regarding fire-resistance rating of the generator room. It should be noted that Clause 5.3 recognizes the fact that certain components of the emergency power supply (i.e., automatic transfer switches or circuit breakers) could be located outside the generator room. In this case, the service room containing such components would have to have a fire-resistance rating not less than 1 h [see references to Sentences 3.6.2.1.(7) and (8) in answer to question 3 above]. Clause 5.3 of C282 mandates protection of wiring between components of the emergency power supply located in different fire rated rooms, and this subject will be addressed below. It should be noted that C282 provides requirements for a generator enclosure located outside the building, as follows:

 

“6.2.1 The emergency electrical supply system shall be located

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 6.8.1 to 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.

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.”

It is interesting to note that C282 does not mandate that such outdoor enclosure must have fire resistance rating, as such fire-resistance rating is not required by the NBCC for the enclosures located outside the building. In this regard, requirement of Rule 24-306 of the CE Code that the generator must be “in a fire-resistant enclosure”, is not consistent with the NBCC and with C282, and the proposal has been submitted to Section 24 S/C of the CE Code – to revise Rule 24-306 accordingly.

 

Does the CE Code mandate protection of electrical conductors against exposure to fire?

Answer. The CE Code, in general, does not deal with this subject, as it mainly applies to the electrical safety. However, there are two specific provisions in the CE Code, where such requirements are explicitly mandated. One of them is in Section 32 (Rule 32-200) – for fire protection of conductors supplying a fire pump, and another, in Section 46 (Rule 46-204) – to compliment requirement of Clause 5.3 of C282 for the benefit of the CE Code users (see below):

“32-200 Conductors (see Appendices B and G)

Conductors from the emergency power source to a fire pump shall

(a) have an ampacity not less than

(i) 125% of the full load current rating of the motor, where an individual motor is provided with the fire pump; and

(ii) 125% of the sum of the full load currents of the fire pump, jockey pump, and the fire pump auxiliary loads, where two or more motors are provided with the fire pump; and

(b) be protected against fire exposure to provide continued operation in compliance with the National Building Code of Canada.

 

46-204 Protection of electrical conductors (see Appendices B and G)

All power, control, and communication conductors 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”.

 

What specific wiring must be protected against exposure to fire, and what are the methods of such protection in accordance with the NBCC?

Answer. Article 3.2.7.10. of the NBCC mandates protection of conductors supplying life safety equipment from the emergency power supply source for a period of 1 h or 2 h (depending on a type of equipment and its location) under specific conditions (i.e.,  whether such life safety equipment is installed in high building, in contained use/jail, in areas of refuge in hospital, or whether such life safety equipment is the electrically connected fire pump installed in any building).  Article 3.2.7.10. of the NBCC lists two methods of such fire protection:  by means of utilizing circuit integrity conductors conforming to ULC S139 fire test or by locating such conductors in dedicated service spaces as follows:

“ 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):

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

serving

  1. i) fire alarms,
  2. ii) emergency lighting, or

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

  1. b) emergency conductors serving fire pumps required to be installed under

Article 3.2.5.18., and

  1. c) electrical conductors serving mechanical systems serving
  2. i) areas of refuge identified in Clause 3.3.3.6.(1)(b), or
  3. ii) contained use areas identified in Clauses 3.3.7.(4)(a) and (b).

2) Except as otherwise required by Sentence (3) and permitted by this Article, electrical conductors that are used in conjunction with systems identified in Sentence (1) shall

  1. a) conform to CAN/ULC-S139, “Fire Test for Evaluation of Integrity of Electrical Power, Data and Optical Fibre Cables,” including the hose stream application, to provide a circuit integrity rating of not less than 1 h (see Note A-3.2.7.10.(2)(a) and (3)(a)), or
  2. b) be located in a service space that is separated from the remainder of the building by a fire separation that has a fire-resistance rating not less than 1 h.

3) Electrical conductors identified in Clause (1)(c) shall

  1. a) conform to CAN/ULC-S139, “Fire Test for Evaluation of Integrity of Electrical Power, Data and Optical Fibre Cables,” including the hose stream application, to provide a circuit integrity rating of not less than 2 h (see Note A-3.2.7.10.(2)(a) and (3)(a)), or
  2. b) be located in a service space that is separated from the remainder of the building by a fire separation that has a fire-resistance rating not less than 2 h.

4) The service spaces referred to in Clauses (2)(b) and (3)(b) shall not contain any combustible materials other than the conductors being protected.

5) Except as stated in Sentences (7) and (9), the electrical conductors referred to in Sentence (1) are those that extend from the source of emergency power to

  1. a) the equipment served, or
  2. b) the distribution equipment supplying power to the equipment served, if both are in the same room [see Note A-3.2.7.10.(5)(b)].

6) If a fire alarm transponder or annunciator in one fire compartment is connected to a central processing unit or another transponder or annunciator located in a different fire compartment, the electrical conductors connecting them shall be protected in accordance with Sentence (2).

7) Fire alarm system branch circuits within a storey that connect transponders and individual devices need not conform to Sentence (2). [See Note A-3.2.7.10.(7).]

8) Except as permitted in Sentence (9), if a distribution panel supplies power to emergency lighting, the power supply conductors leading up to the distribution panel shall be protected in accordance with Sentence (2).

9) Conductors leading from a distribution panel referred to in Sentence (8) to emergency lighting units in the same storey need not conform to Sentence (2).

10) Distribution panels serving emergency lighting units located on other storeys shall be installed in a service room separated from the floor area by a fire separation having a fire-resistance rating of at least 1 h.

11) Conductors leading from a distribution panel to emergency lighting units located on other storeys shall be protected in accordance with Sentence (2) between the distribution panel and the floor area where the emergency lighting units are located.”

 

Are emergency conductors allowed to enter the electrical equipment room when such conductors leave dedicated shafts or spaces where they are installed?

Answer.  Sentences 3.2.7.10.(2)(b) or (3)(b) of the NBCC mandate that such conductors must be installed in “a service space that is separated from the remainder of the building by a fire separation that has a fire-resistance rating not less than” 1 h or 2 h. Sentence 3.2.7.10.(4) states that such service spaces “shall not contain any combustible materials other than the conductors being protected.”  This NBCC requirement is silent on fire protection of such conductors in service rooms. However, each service room that contains life safety equipment must have fire-resistance rating not less than 1 h in accordance with Sentence 3.6.2.1.(8) of the NBCC. This means that when such conductors enter the service room containing the life safety equipment for the purpose of termination on this life safety equipment (i.e., on the distribution or on utilization equipment), such conductors are deemed to be protected against exposure to fire in accordance with the NBCC. Of course, when 2 h fire protection of conductors is required as in case of conductors serving mechanical systems in areas of refuge in hospitals or in contained use areas in jails, not only these conductors, but the service rooms containing such life safety equipment must be protected against exposure to fire for not less than 2 h.

Hopefully, answers to 8 posed questions above will be sufficient for clarification of this subject.

However, as usual, respective AHJs who administer provisions of the NBCC, C282, Z32 and the CE Code in this regard must be consulted accordingly.

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About the Author

Ark Tsisserev is president of EFS Engineering Solutions, Ltd., 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 an electrical safety regulator for the city of Vancouver. He is currently the chair of the Technical Committee for the Canadian Electrical Code and 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: http://www.efsengineering.ca