Although I recently wrote on this subject and received numerous e-mails with appreciation, some readers expressed confusion regarding the following issues:
- scope of the circuit integrity tests under ULC S139 standard,
- use of terminology “combustible material” in service space intended to provide fire protection of conductors,
- use of terminology “service closet” in conjunction with the building code definition “service room,”
- extent of the fire protection of conductors, required by the building code, and
- protection of conductors installed in service rooms.
As such, this article will be dedicated to clarification of the above-noted issues. First of all, let’s revisit the 2015 edition of the National Building Code of Canada (NBCC) requirement for protection of conductors against exposure to fire.
Article 3.2.7.10. of the NBCC 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).
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
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
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
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
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
a) the equipment served, or
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.“
Secondly, let’s evaluate this NBCC Article 3.2.7.10.
As it can be seen from this NBCC Article, Sentence (1) of this Article explains what particular conductors are required to be protected against exposure to fire, Sentences (2) and (3) of this Article specify suitable methods of such protection.
Sentence (4) of Article 3.2.7.10. clarifies that when protection of conductors is chosen by locating conductors in fire rated service spaces, such service spaces must “not contain any combustible materials other than the conductors being protected.”
Sentence (5) of this Article states that the required protection of conductors must be provided “from the source of emergency power to the equipment served, or to the distribution equipment supplying power to the equipment served, if both are in the same room.”
Sentences (6) to (11) of Article 3.2.7.10. indicate that fire alarm system conductors or emergency lighting conductors located on the same storey, are not required to be protected against exposure to fire, as in the event of a fire being started on a specific storey, such fire protection would be meaningless. However, all riser conductors between emergency lighting distribution panels or between fire alarm system transponders and control units located in different fire compartments, would have to be protected, as such fire protection would allow fire alarm system or emergency lighting to function on all storeys not impacted by fire.
Now, it is a perfect time to address the questions raised at the outset of this discussion.
Question 1: What is the scope of the circuit integrity tests under ULC S139 standard?
Answer to question 1: If a circuit integrity cable is chosen as a method of fire protection listed in Clause 3.2.7.10.(2)(a) or (3)(a) above, then each such circuit integrity cable (i.e. Lifeline cable; Draka cable, MI cable, etc.) would have to meet provisions of ULC S139 standard. This standard applies only to the method of a fire test for evaluation of integrity of electrical cables and conductors (i.e. test which determines – how long conductors can carry required current under fire conditions, before such conductors are completely disintegrated).
If, in accordance with the Canadian Electrical Code, Part I (with CE Code), conductors are required to be installed in raceways, then the test assembly is based on installation of the tested conductors in raceways, with all necessary supports, which are mandated for such raceways by the CE Code).
Scope of ULC S139-2012 states in part the following:
“1 SCOPE
1.1 The intent of this fire test method is to determine the integrity of electrical power, data and optical fibre cables which are evaluated for their ability to maintain circuit integrity.
1.2 The electrical power, data and optical fibre cables covered by this Standard are installed to comply
with the requirements in the Canadian Electrical Code and the National Building Code of Canada.
1.5 The performance of the electrical power, data and optical fibre cables is expressed in terms of the retention of circuit integrity at various increments of fire endurance time, as follows:
Circuit Integrity Rating: ____ h with hose stream r, where the hose stream test is not conducted;
Circuit Integrity Rating: ____ h without hose stream”
This means that each circuit integrity cable which is tested in accordance with ULC S139, would be provided with a marking depicting 1 hour or 2-hour rating for protection against exposure to fire. (i.e. marked “ULC S139 2 hr fire rated” cables)
Question 2: What does terminology “combustible material” mean for the purpose of their location in service space intended to provide fire protection of conductors?
Answer to question 2: If a service space is chosen to provide protection of conductors as stated in Clauses 3.2.7.10.(2)(b) or (3)(b) above, such service spaces is a defined entity in accordance with the NBCC as follows:
“Service space means space provided in a building to facilitate or conceal the installation of building service facilities such as chutes, ducts, pipes, shafts or wires. “
Of course, electrical designers and electrical contractors have to validate that the service spaces utilized as means of fire protection of life safety conductors, do not contain any combustible materials (see Sentence 3.2.7.10.(4) of the NBCC):
“3.2.7.10.(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.”
It should be noted that the referenced NBCC requirement applies to “combustible building materials” and not to the electrical wiring which contains combustible jacket. When conductors with combustible jackets are located in non-combustible (metal) raceways, such installation is not considered to be combustible for the purpose of Article 3.1.5.21. of the NBCC (see below):
“3.1.5.21. Wires and Cables
1) Except as required by Sentence (2) and Article 3.1.5.22., optical fibre cables and electrical wires and cables with combustible insulation, jackets or sheathes are permitted in a building required to be of non-combustible construction, provided
a) the wires and cables exhibit a vertical char of not more than 1.5 m when tested in conformance with the Vertical Flame Test – Cables in Cable Trays (FT4 rating) in CSA C22.2 No. 0.3, “Test Methods for Electrical Wires and Cables,”
b) the wires and cables are located in
i) totally enclosed noncombustible raceways (see Note A-3.1.4.3.(1)(b)(i)),
ii) masonry walls,
iii) concrete slabs,
iv) a service room separated from the remainder of the building by a fire separation having a fire-resistance rating not less than 1 h, or
v) totally enclosed non-metallic raceways conforming to Clause 3.1.5.23.(1)(b),“
It should be also noted that Clause 5.11.7 of the CSA standard C22.2 No. 0 “General requirements” has the following statement regarding metal enclosures for electrical equipment (i.e. for boxes and raceways):
“5.11.7
Where electrical equipment is installed in an aluminum, iron, or steel enclosure that is in accordance with a safety Standard listed in Appendix A of the Canadian Electrical Code, Part I, such enclosures are deemed to be non-combustible for the purpose of Article 3.1.9.2. of the National Building Code of Canada.“
So, any conductors that are installed in non-combustible/metal raceways do not represent “any combustible materials” for the purpose of Sentence 3.2.7.10.(4) of the NBCC, as electrical conductors are part of electrical products, and every piece of electrical product is not a “material.” It is an integrated assembly of interconnected components designed, constructed, tested, and certified to the specific safety standards for electrical products, listed in Appendix A of the CE Code. When electrical equipment is housed in a metal enclosure, and when electrical conductors are installed in metal raceways, such enclosures and raceways are deemed by the CSA standard C22.2 No. 0 to be non-combustible in conjunction with Article 3.1.9.2. of the NBCC (see Article 3.1.9.2. of the NBCC below):
“3.1.9.2. Combustibility of Service Penetrations
1) Except as permitted by Articles 3.1.9.3. and 3.1.9.5., pipes, ducts, electrical outlet boxes, totally enclosed raceways or other similar service equipment that penetrate an assembly required to have a fire-resistance rating shall be noncombustible, unless the assembly was tested incorporating that service equipment.“
Question 3: What does the terminology “service closet” in conjunction with the building code definition “service room” mean?
Answer to question 3: Terminology “service closet” is not used in the NBCC. The NBCC uses terminology “water closets,” “linen closets,” etc., but such use of closets has no relevance to the subject of this discussion.
Many industry experts (i. e. architects, code consultants, etc.) indicate that it is accepted practice to apply terminology “service closets” similarly to the application of service rooms, where such closets are used for installation of electrical equipment. (see definition of “service room” below):
“Service room means a room provided in a building to contain equipment associated with building services.”
Therefore, if a life safety equipment is installed in such service closets, then each such service closet must be separated from the remainder of the building by a fire separation that has a fire-resistance rating not less than 1 hour. It should be noted that in some areas, such as area of refuge in hospitals, jails or prisons, a 2 hour protection of electrical conductors against exposure to fire is required, and Sentence 3.2.7.10.(3) shown above, reflects this fact.
So, what is a “service closet” for the purpose of Sentence 3.2.7.10.(4)? Is it a service space or a service room?
As such service closets house electrical equipment and electrical conductors, many AHJ’s and code consultants consider such electrical service closets to be service rooms, and if each such service is separated from the remainder of the building by a fire separation with a fire-resistance rating not less then 1 h and does not contain any combustible materials, then the safety objective of Sentence 3.2.7.10.(4) shown above, is met. Of course, this particular issue requires further clarification.
So, electrical equipment in non-combustible enclosures and conductors in non-combustible raceways, located in such fire-rated service closets, are deemed to be protected in accordance with Sentences 3.2.7.10(2)(b) or (3)(b) and Sentence 3.2.7.10.(4) of the NBCC.
The proposal – to clarify Article 3.2.7.10. of the NBCC, has been already submitted. Until such clarification is made to the NBCC, local AHJ’s might want to consider providing local interpretations on application of terminology “service closet” for the purpose of Article 3.2.7.10. of the NBCC.
Question 4: What is the extent of the fire protection of conductors, required by the building Code?
Answer to question 4: When electrical conductors are connected to such life safety equipment as fire pumps, smoke control, smoke venting equipment, mechanical systems serving areas of refuge or fire fighters’ elevators, these conductors must be protected from the source of the emergency power supply (from the emergency generator) to the equipment being served. This fact is reflected by Sentence 3.2.7.10.(5) of the NBCC (see above).
Conductors installed on a floor area for connection to fire alarm system devices located on that particular floor area or conductors installed on a floor area for connection to the emergency lighting located on that floor area, do not need to be protected, and this fact is confirmed by Sentences 3.2.7.10.(7) and (9) of the NBCC. However, trunk/riser (main stem) conductors of a fire alarm system or of emergency lighting, which serve more than one story, must be protected against exposure to fire (see Sentences 3.2.7.10.(6); (8); (10) and (11) of the NBCC). Any junction boxes or access points required for the protected conductors must be also protected with listed access panels which have been tested to limit the temperature rise on the unexposed side to less than 90° C for one hour. An air space shall be provided between the access panel and the conductors, to ensure that there will be no contact. Building Code specialists should be always consulted regarding such protection of junction boxes or access points.
Question 5: How are conductors protected, when these conductors are installed in service rooms?
Answer to question 5: Service rooms that contain life safety equipment, must have a fire-resistance rating of not less than 1 h (see Sentence 3.6.2.1.(8) of the NBCC below):
“3.6.2. Service Rooms
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.”
Therefore, if a life safety equipment is installed in service rooms, then each such service room must be separated from the remainder of the building by a fire separation that has a fire-resistance rating not less than 1 h. (in some areas – to protect certain life safety equipment and conductors, i.e. hospitals, jails, etc., 2 h fire rating is required.
So, electrical equipment in non-combustible enclosures and conductors in non-combustible raceways, located in such fire-rated service rooms, are deemed to be protected in accordance with Sentences 3.2.7.10(2)(b) or (3)(b) and 3.2.7.10.(4) of the NBCC.
Hopefully, the discussion above further clarifies this potentially ambiguous subject. However, as usual, the local AHJ’s enforcing provisions of the legally adopted local building codes should be always consulted.
