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I am doing all my own wiring on a new outbuilding (my well pump house) to save money. I want to have an electrician come in afterwards and simply verify that it was done correctly.

When you run romex from an outlet back to the breaker box, do you strip the yellow outer sheath off where it enters the breaker box, or do you only strip the last few inches to expose the hot, neutral, and ground so you can strip them and make your connection?

In other words, does the yellow outer sheath extend well into the breaker box?

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Typically it is stripped back to where it enters the enclosure. There is a code minimum, 1/4", but no maximum. It could be argued that leaving most of the sheathing on is poor workmanship.

Sometimes I leave an inch or two to write the circuit ID on the sheath.

NEC 2011

312.5 Cabinets, Cutout Boxes, and Meter Socket Enclosures Conductors entering enclosures within the scope of this article shall be protected from abrasion and shall comply with 312.5(A) through (C).

C) Cables. Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure.

Exception: Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) and not more than 3.0 m (10 ft) in length, provided all of the following conditions are met:

a) Each cable is fastened within 300 mm (12 in.), measured along the sheath, of the outer end of the raceway.

b) The raceway extends directly above the enclosure and does not penetrate a structural ceiling.

c) A fitting is provided on each end of the raceway to protect the cable(s) from abrasion and the fittings remain accessible after installation.

d) The raceway is sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway.

e) The cable sheath is continuous through the raceway and extends into the enclosure beyond the fitting not less than 6 mm (¼ in.).

f) The raceway is fastened at its outer end and at other points in accordance with the applicable article.

g) Where installed as conduit or tubing, the allowable cable fill does not exceed that permitted for complete conduit or tubing systems by Table 1 of Chapter 9 of this Code and all applicable notes thereto.

  • Yes, the sheathing must remain intact at least a little way into the box; that's what the cable clamp clamps onto. – Harper Mar 30 '17 at 21:42
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    The 2017 NEC added a specific rule in 314.17 (B) for NM cable entering metal boxes, but it's the same 1/4" rule like you said. – Robert Nubel Mar 30 '17 at 21:50
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    @RobertNubel -- Art. 314 is for boxes (i.e. junction boxes) while Art. 312 is for cabinets (i.e. housings for panelboards, switchboards, and switchgear) – ThreePhaseEel Mar 30 '17 at 22:15

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