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Friday, May 20, 2016
Question:
Good morning,
In 501.15(b)(2) states that a conduit seal need not be explosion proof. Are there any non-explosion proof seals that are on the market? I’m starting to see products available for sealing of conduits that satisfy the code for sealing service conduits and conduits of different temperatures. They are a closed cell two part expandable foam. Would this satisfy the code for div 2 boundary seals?
Also in 501.15(a)(4) it does not specifically say it does not need to be explosion proof but requires the seal designed to minimize the passage of vapors and gasses. It would seem that the above mentioned would also satisfy this.
Thanks, Zach
A
Answer:
Hey Zach thanks for your question. Section 501.15(A)(4) applies to Class I, Division 1 boundary seals and 501.15(B)(2) applies to Class I Division 2 boundary seals. Equipment suitability must be determined by the AHJ as stated in 500.8(A) and listing or labeling of equipment is often required by them. I agree that the wording in 501.15(A) could be improved by specifically stating that conduit seals be explosionproof but 501.15(C)(1) requires integral sealing means or fittings listed for the location. Here is your opportunity to submit a Public Input for the 2020 NEC. The last sentence of 501.15(B)(2) allows the Division 2 boundary seal to be not of the explosionproof type but it must be identified for minimizing the passage of gasses. I am not aware of any seals that are identified for this purpose other than the explosionproof ones. The sealing required by 300.7 is not sufficient for the sealing required for hazardous locations.