NM sheathing extending into panel

[Chris Bernhardt]

In the book "Electrical Inspection of Existing Dwellsings", Douglas Hansen et. al., its mentioned that over extending sheathed cable into the panel is poor workmanship. Is there a particular NEC cite to back this up?

Chris, Oregon

[ozofprev]

Hi Chris,

No. The NEC says the sheathing must extend at least a quarter inch into the panel, but does not specify a maximum sheathing length. That quarter inch ensures protection of the conductor at the panel entrance.

The workmanship issue has to do with the bending of the conductors. Look at any panel, and you will see that the conductors are bent almost immediately to follow header and gutter space. By minimizing the amount of sheathing, you are maximizing the 'room' for this bend at the entry point.

Just look at Hansen's 4.63. Imagine how much more crowded the header space would be if the white sheathing extended and did not allow the conductors to immediately bend. Good question!

Originally posted by Chris Bernhardt

In the book "Electrical Inspection of Existing Dwellsings", Douglas Hansen et. al., its mentioned that over extending sheathed cable into the panel is poor workmanship. Is there a particular NEC cite to back this up?

Chris, Oregon