The 2005 edition of the National Building Code of Canada (NBCC) has been already adopted by the majority of provincial and territorial jurisdictions. This means that one change that has been introduced into the latest edition of the NBCC could be very interesting (and very relevant) to the electrical designers, installers and electrical safety regulators.
This change to the NBCC requires that carbon monoxide alarms must be provided in each suite of residential occupancy where a fuel-burning appliance is installed in that suite.
If a fuel-burning appliance is installed in a service room, and this service room is not located in a suite of residential occupancy, the NBCC mandates installation of a carbon monoxide alarm in every suite of residential occupancy that shares a wall or floor/ceiling assembly with the service room, and in addition, installation of a carbon monoxide alarm in that service room.
The NBCC also requires installation of a carbon monoxide alarm in each suite of residential occupancy that shares a wall or floor/ceiling assembly with a storage garage or in a suite of residential occupancy that is adjacent to an attic or crawl space to which that storage garage is also adjacent.
The Building Code identifies the location of a carbon monoxide alarm in the following areas of the residential suite: (a) inside each bedroom, or (b) outside each bedroom, within 5 m of each bedroom door, measured following corridors and doorways.
“So what, and why do we have to be concerned?” may ask the electrically minded readers.
It should be noted that the major change that has been introduced in the NBCC 2005 in comparison with the earlier editions of the National Building Code now will affect every dwelling unit with a fuel-burning appliance.
While the previous editions of the NBCC mandated carbon monoxide detectors in those suites where a solid-fuel burning appliance is installed, the requirements for carbon monoxide alarms in the NBCC 2005 are not limited to solid-fuel burning appliances only.
Specific provisions for installation of carbon monoxide alarms may be found in Subsection 6.2.4. and in Article 9.32.4.2 of the NBCC.
“So far – so good” may say the readers of this column, “but what’s in this requirement that might affect us?”
The trick is in a very inconspicuously looking requirement of the Building Code. This requirement is articulated in Sentence 6.2.4.1.(2)© and in Sentence 9.32.4.2.(2)© of the NBCC and it states that the carbon monoxide alarms required by one of these articles must: “Have no disconnect switch between the overcurrent device and the carbon monoxide alarm, where the carbon monoxide alarm is powered by the dwelling unit’s electrical system”. This means that if a permanently connected carbon monoxide alarm is installed in a dwelling unit, wiring of this piece of electrical equipment must be similar to the provisions of Rule 32-110 of the CE Code for smoke alarms.
This means that an installer of such permanently connected carbon monoxide alarm would have to install the carbon monoxide alarm so that it is powered by a circuit that supplies a mix of lighting and receptacles, and the circuit cannot be protected by a GFCI or AFCI, and the circuit has no disconnecting means (On-Off switches) between the carbon monoxide alarm and the branch-circuit overcurrent device (the circuit breaker located in the dwelling unit panelboard).
This also means that if more than one permanently connected carbon monoxide alarm is installed in a dwelling unit, all such devices must be interconnected similarly to the NBCC and the CEC provisions for permanently connected smoke alarms.
However, such requirement is not specifically articulated in the CEC, and the installers of electrical equipment appear to be in the dark regarding this very important safety requirement of the Building Code.
Needless to say, Subcommittee on Section 32 of the CE Code has already recognized the existing gap between the NBCC and the CEC and recommended necessary changes to Rule 32-110 in order to capture installation requirements for permanently connected carbon monoxide alarms.
It is interesting to note that some jurisdictions do not allow use of battery-powered carbon monoxide alarms, but mandate only installation of permanently connected devices, similarly to the NBCC provisions for installation of smoke alarms.
Furthermore, these jurisdictions mandate interconnection of carbon monoxide alarms with smoke alarms installed in a dwelling to ensure that the safety alarm sounds will be expediently transmitted throughout the dwelling.
City of Vancouver, for example, has published an explanatory bulletin to interpret the requirements of the Vancouver Building By-law 2007 for installation of carbon monoxide alarms as follows:
1. Sentence 6.2.4.1.(2) to be read to require that carbon monoxide alarms: “be permanently connected to an electrical circuit and shall have no disconnect switch between the overcurrent device and the carbon monoxide alarm, and be wired so that its activation will activate smoke alarms required by Article 3.2.4.20”
2. Sentence 9.32.4.2.(2) to be read to require that carbon monoxide alarms: “be permanently connected to an electrical circuit and shall have no disconnect switch between the overcurrent device and the carbon monoxide alarm, and be wired so that its activation will activate smoke alarms required by Subsection 9.10.19”
This interpretation by the city of Vancouver was intended to improve performance and reliability of the required carbon monoxide alarms by mandating their permanent connection similarly to the requirement for connection of smoke alarms, and by mandating interconnection of carbon monoxide alarms with smoke alarms installed in a dwelling unit.
It is also interesting to note that the industry has immediately responded to the Building Code requirement in respect to carbon monoxide detectors by introducing an approved combination of a smoke alarm/carbon monoxide alarm.
Although each of these separate devices is designed and constructed in accordance with different standards, the Underwriters Laboratory of Canada (ULC) certifies such combination devices that meet the NBCC specific requirements for location of smoke alarms and for location of carbon monoxide alarms and such combination devices are readily available on the market.
Although this article intends to provide general information on this important life safety issue, the authority having jurisdiction must be consulted in each case of installation of these devices in order to meet specific requirements of the AHJ for this particular subject.
