National Electrical Installation Standards

Standards as High as Your Own

Wednesday, September 19, 2018


Good morning, First, thank you for continuing this forum. I was recently called on to connect a radon blower. The installer left a switch kit provided from the blower manufacturer. I don’t know if the kit comes with the blower or if it is a separate item purchased by the radon mitigation contractor. The kit contained a weatherproof box, switch, weatherproof cover, two liquid- tight cord connectors and a 30 inch piece of SJOW cord. An image of the kit can be seen here: It is billed as an exterior switch kit.

400.12(1) states that cord cannot be used as a substitute for fixed wiring unless specifically permitted in 400.10. This installation does not seem to fit any of the uses permitted in 400.10(A). The blower is connected to the rigid 3” piping with flexible couplings and pipe clamps to allow replacement without cutting into the fixed piping. But it should not need frequent repair or changing. I think it might be a stretch saying it complies with 400.10(A)(8). There is nothing in the instructions supplied with the blower that mentions the switch kit, only that the installation must be done according to the NEC. There were no instructions supplied with the switch kit. Do you think installing the blower using the cord in this kit is acceptable?




Hey Bob thanks for your question and you are welcome. You are correct that flexible cords are not allowed to be used as a substitute for fixed wiring as stated in 400.12(1). But they are allowed based on the uses in 400.10 such as 400.10(7) to prevent transmitting noise or vibration. The flexible couplings you describe could be an acceptable use based on 400.10(8) if the radon fan is intended or identified for use with a flexible cord. An attachment plug must be used in that case as stated in 400.10(B). This is a common method used for kitchen waste disposers and is specifically addressed in 422.16(B).

It appears the radon fan is listed so you might want to contact the manufacturer and listing laboratory and ask if they intend the fan be connected that way. Usually the instructions with listed equipment provides the details necessary for installation and it seems strange there are none so maybe the kit is not listed as part of the assembly.

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