hi.
i'm roughing in my basement and looking for help on 2 questions:
1. what is the min/max nm sheathing required in electrical box?
2. what min length of wire is required to extend beyond electrical box?
Thanks!
Brad
Here is a copy & paste from the 2008 NEC.
314.17(C)
(C) Nonmetallic Boxes and Conduit Bodies. Nonmetallic
boxes and conduit bodies shall be suitable for the lowest
temperature-rated conductor entering the box. Where nonmetallic
boxes and conduit bodies are used with messengersupported
wiring, open wiring on insulators, or concealed
knob-and-tube wiring, the conductors shall enter the box
through individual holes. Where flexible tubing is used to
enclose the conductors, the tubing shall extend from the last
insulating support to not less than 6 mm (1⁄4 in.) inside the
box and beyond any cable clamp. Where nonmetallicsheathed
cable or multiconductor Type UF cable is used,
the sheath shall extend not less than 6 mm (1⁄4 in.) inside
the box and beyond any cable clamp. In all instances, all
permitted wiring methods shall be secured to the boxes.
Exception: Where nonmetallic-sheathed cable or multiconductor
Type UF cable is used with single gang boxes not
larger than a nominal size 57 mm × 100 mm (21⁄4 in.
× 4 in.) mounted in walls or ceilings, and where the cable
is fastened within 200 mm (8 in.) of the box measured along
the sheath and where the sheath extends through a cable
knockout not less than 6 mm (1⁄4 in.), securing the cable to
the box shall not be required. Multiple cable entries shall
be permitted in a single cable knockout opening.
300.14
300.14 Length of Free Conductors at Outlets, Junctions,
and Switch Points.
At least 150 mm (6 in.) of free
conductor, measured from the point in the box where it
emerges from its raceway or cable sheath, shall be left at
each outlet, junction, and switch point for splices or the
connection of luminaires or devices. Where the opening to
an outlet, junction, or switch point is less than 200 mm
(8 in.) in any dimension, each conductor shall be long enough
to extend at least 75 mm (3 in.) outside the opening.
Exception: Conductors that are not spliced or terminated
at the outlet, junction, or switch point shall not be required
to comply with 300.14.
Edit: Bold print by me.
