NM Romex Jacket in Panel

[ahinders (Alan Hinders)]

Wondering what the actual rules are for NM cable in a service panel still having its outside jacketing intact.

What is the concern with having this jacketing on the wire inside the panel?

[dwigger (David Wigger, CMI, Retired)]

I believe the only ‘rule’ is:
(e) Each cable sheath extends not less than ¼ in. into the panel board.

Now, when I see it in a panel it suggests to me that work was done by a ‘non-professional’. Note the missing clamp where the NM enters at the base.

[jpope (Jeffrey Pope, CMI, CHI, CPI, ICC)]

@dwigger

I believe the only ‘rule’ is:
(e) Each cable sheath extends not less than ¼ in. into the panel board.

Correct. There is no maximum.

[rlewis5 (Roy Lewis, CERTIFIED MASTER INSPECTOR RETIRED)]

I’d be more concerned about the missing grommet/bushing.

[rmeier2 (Robert Meier)]

@jpope

Correct. There is no maximum.

There is no minimum either.

[lkage (Larry Kage, CMI)]

@Robert_Meier

There is no minimum either.

Do you mean as long as the sheathing jacket is clamped into the connector?

[jwriter (Jeff Writer, HI-1883)]

Ugly, but not a problem. Its not hurting anything.

[rlewis5 (Roy Lewis, CERTIFIED MASTER INSPECTOR RETIRED)]

@lkage

Do you mean as long as the sheathing jacket is clamped into the connector?

Larry!
What connector are you referring to?

[rmeier2 (Robert Meier)]

@lkage

Do you mean as long as the sheathing jacket is clamped into the connector?

Yes, the 1/4" rule is for nonmetallic boxes.

[rlewis5 (Roy Lewis, CERTIFIED MASTER INSPECTOR RETIRED)]

Robert…
Not less than 1/4" correct?

[sfetty (Dave Fetty, CMI)]

@rlewis5

I’d be more concerned about the missing grommet/bushing.

Good catch.

[sfetty (Dave Fetty, CMI)]

@ahinders

Wondering what the actual rules are for NM cable in a service panel still having its outside jacketing intact.

What is the concern with having this jacketing on the wire inside the panel?

Sticking your fingers into service panels is not advised… you have no idea if all wiring was properly stripped at installation. I’ve seen many instances of damaged wiring insulation leaving exposed conductors.

[rmeier2 (Robert Meier)]

@rlewis5

Robert…
Not less than 1/4" correct?

Yes, not less than 1/4" for certain nonmetallic boxes. Here’s the NEC section:

314.17(C) Nonmetallic Boxes and Conduit Bodies. Nonmetallic
boxes and conduit bodies shall be suitable for the lowest
temperature-rated conductor entering the box. Where nonme‐
tallic boxes and conduit bodies are used with messenger-
supported 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 nonmetallic-sheathed
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 (2 1 ∕ 4 in. × 4 in.) mounted in walls or ceilings,
and where the cable is fastened within 200 mm (8 in.) of the box meas‐
ured 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.

[lkage (Larry Kage, CMI)]

@rlewis5

Larry!
What connector are you referring to?

This, Roy, what Robert answered later:

Where nonmetallic-sheathed
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.

[Jim_Port]

The flip side is that the NEC also requires 6 " or more of free conductor outside the sheath.

[pabernathy (Paul Abernathy, CMI®, CMECP® Electrical Code Academy,Inc.)]

@Robert_Meier

Yes, not less than 1/4" for certain nonmetallic boxes. Here’s the NEC section:

Yep and the rule also applies to metallic boxes as well now in the 2017 NEC.

314.17(B) Metal Boxes and Conduit Bodies. Where metal boxes or
conduit bodies are installed with messenger-supported wiring,
open wiring on insulators, or concealed knob-and-tube wiring,
conductors shall enter through insulating bushings or, in dry
locations, through flexible tubing extending from the last insulating
support to not less than 6 mm (1∕4 in.) inside the box and
beyond any cable clamps. Where nonmetallic-sheathed 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. Except as provided in 300.15(C), the wiring shall
be firmly secured to the box or conduit body. Where raceway
or cable is installed with metal boxes or conduit bodies, the
raceway or cable shall be secured to such boxes and conduit
bodies.

[rmeier2 (Robert Meier)]

@pabernathy

Yep and the rule also applies to metallic boxes as well now in the 2017 NEC.

314.17(B) Metal Boxes and Conduit Bodies. Where metal boxes or
conduit bodies are installed with messenger-supported wiring,
open wiring on insulators, or concealed knob-and-tube wiring,
conductors shall enter through insulating bushings or, in dry
locations, through flexible tubing extending from the last insulating
support to not less than 6 mm (1∕4 in.) inside the box and
beyond any cable clamps. Where nonmetallic-sheathed 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. Except as provided in 300.15(C), the wiring shall
be firmly secured to the box or conduit body. Where raceway
or cable is installed with metal boxes or conduit bodies, the
raceway or cable shall be secured to such boxes and conduit
bodies.

Good point on the metal boxes but even under the 2017 NEC this wouldn’t apply to a NM connector in a panel as outlined in the OP.

[mgleeson (Michael Gleeson, 16000070526)]

@Robert_Meier

Good point on the meal boxes but even under the 2017 NEC this wouldn’t apply to a NM connector in a panel as outlined in the OP.

Why do you say that it wouldn’t apply? Is the panel not a metal box?

[rmeier2 (Robert Meier)]

@mgleeson

Why do you say that it wouldn’t apply? Is the panel not a metal box?

No, the panel enclosure is technically a cabinet and covered under a different code article, article 312. Boxes are under Article 314. An example of the metal box that Paul mentioned looks like this:

https://www.cesco.com/images/products/CooperCrouse-Hinds/thumb/TP449thumb.jpg

[pabernathy (Paul Abernathy, CMI®, CMECP® Electrical Code Academy,Inc.)]

@Robert_Meier

Good point on the meal boxes but even under the 2017 NEC this wouldn’t apply to a NM connector in a panel as outlined in the OP.

Yup…it was to supplement your nonmetallic box statement.