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Friday, June 9, 2023
Question:
Hello CQD, I have been involved in a project in which there has been much debate about whether motors in Class I, Division 2 areas require to have seal-offs installed. In our situation, the motors in the Class I, Division 2 area meet the requirements of 501.125(B)(3), (Be open or non-explosion proof enclosed motors, such as squirrel-cage induction motors without brushes, switching mechanisms, or similar arc-producing devices that are not identified for use in a Class I, Division 2 location.) The cables being used for this project do not require sealing per section 501.15(E)(2). However, we have not been able to find whether the requirements are any different when installing a motor in a Class I Division 2 location that meets Section 501.125(B)(3). Would the cable require a seal-off at the installed motor termination? Any clarification that you could provide on this issue would be welcomed. Thanks, Edwin Mast
A
Answer:
Hi Edwin, thank you for the question. There are two main reasons we use sealing fittings in classified locations. (1) We seal the wiring method at the classified area boundary to prevent flammable gases or vapors from passing thru an electric conduit, raceway, or cable from the classified area to an unclassified area. (2) When entering enclosures where electrical terminations or components are installed in classified areas to prevent the spread of fire/explosion ignited from the electrical component capable of creating an arc or spark during operation.
The cable described in the question would not require a sealing fittings to prevent the spread of flammable gases or vapors as it meets the criteria specified in Section 501.15(E)(2).
As for the terminations and the motor connection, Section 501.15(E)(1) provides guidance on this stating that a sealing fitting is only required in Class I Division 2 locations at terminations where the cables enter an enclosure that is required to be explosionproof. Since the motor specified, complies with Section 501.125(B)(3) is not required to be an explosionproof enclosed motor, a sealing fitting would not be required.