Sentence 4.1.4.1.(2) of the 2015 National Fire Code of Canada (NFC) is an outlier – and, prescriptive code requirements that differ from the majority are interesting.
For context – NFC Sentence 4.1.4.1.(2) is provided below:
Where refrigerators are used to keep Class I liquids, they shall be designed so that
(a) electrical equipment located within the storage compartment, within the outer shell, on the door and on the door frame of the refrigerator is in conformance with CSA C22.1, “Canadian Electrical Code, Part I,” for Class I, Zone 0 or 1 hazardous locations based on the frequency of occurrence and duration of an explosive gaseous atmosphere, and
(b) electrical equipment mounted on the outside surface of the refrigerator is
i) in conformance with CSA C22.1, “Canadian Electrical Code, Part I,” for Class I, Zone 2 hazardous locations, or
ii) located above the top of the storage compartment.
One reason that this Sentence is interesting, in my opinion, is because it states prescriptive requirements for hazardous area classifications for a specific type of equipment. That is – the Sentence designates the extent of Class I Zones in proximity to, and within, refrigerators that house flammable liquids.
Why is this an outlier? Generally, where flammable or combustible liquids or combustible dusts and/or flyings are regulated under the NFC, the Code directs the user to comply with the Canadian Electrical Code (CEC, CSA C22.1). There is a clear boundary in the respective scope of these Codes. The CEC defines, regulates, and informs on hazardous area classifications related to electrical equipment installations – and has largely been adopted in most jurisdictions either directly or with local modifications.
Generally, where flammable or combustible liquids or combustible dusts and/or flyings are regulated under the NFC, the Code directs the user to comply with the Canadian Electrical Code
To the best of my knowledge, this is the only instance in the NFC that directly prescribes hazardous area classifications – which is otherwise the domain of the CEC.
The applications of this Sentence often capture those refrigerators in laboratories where flammable liquids are stored. For information, compliant units may be known as “lab-safe” or “de-sparked” refrigerators; however, the terminology is not consistent. It is always necessary to confirm with a laboratory refrigerator manufacturer or distributor that the unit meets the Canadian requirements where solvents will be stored inside a refrigerator.
If you’ve inspected or reviewed laboratories in the past, you will know that it is not uncommon to observe noncompliant, unlisted, conventional refrigerators in laboratory environments. The hazard of an unintentional flammable liquid spill inside the refrigerator, and the evolution of flammable vapours within the confined space of the storage compartment, represents an explosion risk. The vapours generated are contained to a limited space and could be exposed to an ignition source either within the storage compartment or directly below the unit upon opening the door (as the vapours are frequently heavier-than-air). As a result, there is a history of fires and explosions in laboratories where flammable liquids have been stored in conventional refrigerators.
The prescriptive requirements of NFC Sentence 4.1.4.1.(2) may not be consistent with the electrical design approach developed for a project, if the electrical engineer or responsible designer is not aware of this specific Sentence. Additionally, the cost associated with an appropriately rated refrigerator is significant, in comparison to a conventional unit. It is critical that the design team, the responsible practitioners, and the authority having jurisdiction be aware of this NFC outlier, and ensure that the electrical design and equipment selection is compliant with Sentence 4.1.4.1.(2).
I am interested in your experiences! Please share your observations and perspectives in the comments section below – are you aware of other outliers?
One Response
Great post Melinda and very relevant in my world at the moment!
Due to that outlier, I’ve recently reached out to TSASK Electrical Inspections with a scenario that involves labs storing flammable liquids in modified unlisted refrigerators. More specifically, the question from the owners of the lab, “if we’re replacing current unlisted refrigerators, what will be acceptable?” Apparently, while “lab-safe” refrigerators are readily available at a very large cost, CEC approved “lab-safe” refrigerators are difficult if not impossible to track down.
Here’s what TSASK had to say about these refrigerators:
“The Canadian Electrical Code (CEC or CSA 22.1) would require the equipment be rated for use in a hazardous location and certified for use in Canada. Section 18 of CSA 22.1 defines the types of hazardous locations and the ratings of equipment allowed in the different classifications of hazardous zones. Our department relies on engineers to classify the level of hazards and to reduce, minimize or lower (reduce the restrictions) the classification of the hazardous areas. A common trade term for equipment would be explosion proof or certified for use in explosive or flammable atmospheres. A quick google search shows several options for fridges that are recognized as OSHA and NFPA rated to be installed in area where hazardous liquids and vapours could be or are present. These types of units may not be certified for use in Canada and may require field certification to be certain they meet the safety requirements for use in Canada. There is a list of recognized certification markings and companies that perform field certifications available at the link below. (The information pertaining to this subject starts on Page 18.)
https://www.tsask.ca/public/images/ElectricalCodeInterpretations-2018.pdf.”
Long story short, all fridges that were being sourced had no Canadian approvals and would have to go through the field certification process which is a whole different ball game.
Is this a problem nation wide or just in Saskatchewan? Anyone know a good supplier of these fridges that would not require field certification?