When asked if we could build a Custom Fixture Whip in 3/8” Steel Flex with 3-12 AWG wires and 2-16 AWG wires, I wondered if this amount of wire would fit inside our 3/8” Steel Flex—even with an External Connector. So I consulted my 2014 NEC code book, and coincidentally, this very topic arose during a recent continuing education credits course I took.

According to my calculation, the total cross-sectional area of the five conductors exceeded the allowable 40% fill rate of the 3/8” conduit. I concluded that we would have to use 1/2” Steel Flex.

As a result of this inquiry, I thought it might be valuable to share this table—Maximum Number of Insulated Conductors in 3/8-inch Flexible Metal Conduit.

If you’ve got questions, we’re here to help figure out the answers. Call Tim Nelson, EPCO Inside Sales Supervisor and Master Electrician – 800.336.1976 or Email – sales@engproducts.com.

Engineered Products Company Inc. (EPCO) is the premier brand supplier of specialty products to electrical distributors and contractors. Headquartered in Minnetonka, MN (a suburb west of Minneapolis), EPCO has supported the electrical industry since 1976. EPCO supplies a broad range of standard and unique consumables for commercial, industrial, residential and agriculture buildings.