Boring shallow studs

Residential conduit installation requires some special consideration when there's a possibility that screws or nails can cause penetration. When a raceway of this type (FMC)is installed where it is exposed or concealed and is run through bored holes in joists, rafters or wood members, the holes must be bored so that the edge of the hole is not less than 1- in. from the nearest edge of the wood member.

Joe Tedesco

Jan. 1, 2002

Residential conduit installation requires some special consideration when there's a possibility that screws or nails can cause penetration.

When a raceway of this type (FMC)is installed where it is exposed or concealed and is run through bored holes in joists, rafters or wood members, the holes must be bored so that the edge of the hole is not less than 1-¼ in. from the nearest edge of the wood member. In this case since a 2 in. × 3 in. wooden stud was used in this shed, compliance with this 300.4(a)(1) is not possible. A 1/16-in. thick steel plate, or bushing, is required to be installed on both sides of this stud to protect the flexible metal conduit.

Be sure to check for the “appropriate length and width” of this protection. Also, see Section 300.4(A)(1), Exception, where this protection would not be required when rigid metal conduit (RMC), intermediate metal conduit (IMC), rigid nonmetallic conduit (RNMC) or electrical metallic tubing “thinwall” (EMT)was used in this manner.