What is type NMD wire?

'NMD' stands for 'non-metallic dry'. The jacket, or sheathing, around the wire is not a metallic material and this household wire is for dry locations only. Other types of wiring may have a metal sheathing or be rated for exterior or wet conditions. You are most likely to see NMD with a number, such as NMD90 (or NMD7).

What is NMD90 wire used for?

NMD90 wire should be used for household wiring. For the wiring of your home, you generally will be using 12 or 14 gauge wire. Appliances will require wires with a 10, 8, or 6 gauge. Appliances and devices that require a lot of amperage (like water heaters, stoves, dryers, and air conditioning units) usually need larger gauges.

NMD90 comes in two types, two or three copper conductor with insulation and an overall jacket made of moisture resistant and flame retardant PVC. This wire is used for open work in dry locations or concealed work in damp locations where not exposed to mechanical injury. It is approved for use with ceiling fixtures. NMD cable cannot be installed outside, regardless of the wiring method enclosing it.

Reference: 334.12(B)(4) not permitted in a wet or damp location, 300.9 Raceways in Wet Locations Above Grade. Where raceways are installed in wet locations above grade, the interior of these raceways shall be considered to be a wet location. Insulated conductors and cables installed in raceways in wet locations above-grade shall comply with 310.8(C).