I have some questions in regards to running electrical in an exposed, unfinished basement environment. I understand that wire running parallel to floor joists should be at least 1.25" above the bottom of the joist and fastened at regular intervals (4.5 ft?). My question: when it is required that the wire jog 90 degrees (perpendicular to the joists) and pass through drilled holes, does this wire have to be in conduit? To avoid the conception that someone could "hang" something on this wire. Also, do the holes where the wire passes through have to filled with a fire retardant?

1 Answer 1


Conduit is not required where a cable runs through bored holes in joists. If you're worried about it, you could install running boards between the joists above or below the cable.

National Electrical Code

Chapter 3 Wiring Methods and Materials

Article 334 Nonmetallic Sheathed Cable: Types NM, NMC, and NMS

334.17 Through or Parallel to Framing Members. Types NM, NMC, or NMS cable shall be protected in accordance with 300.4 where installed through or parallel to framing members. Grommets used as required in 300.4(B)(1) shall remain in place and be listed for the purpose of cable protection.

Fire retardant is also not typically required, unless the cable is passing between dwelling units, into a garage, or between floors.

National Electrical Code 2014

Chapter 3 Wiring Methods and Materials

Article 300 Wiring Methods

300.21 Spread of Fire or Products of Combustion. Electrical installations in hollow spaces, vertical shafts, and ventilation or air-handling ducts shall be made so that the possible spread of fire or products of combustion will not be substantially increased. Openings around electrical penetrations through fire-resistant-rated walls, partitions, floors, or ceilings shall be firestopped using approved methods to maintain the fire resistance rating.

This is of course unless there are any local amendments.

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