334.30 Securing and Supporting.
Code Change Summary: Revised code language on supporting Nonmetallic Sheathed Type NM cable.
Some electrician like to leave a coil of cable at a box to make things easier on future repair work, or in case the box needs to be moved slightly after the sheetrock is installed and cabinets are placed. Securing and supporting requirements for NM cable are found in Section 334.30.
The general rule for NM cable is to secure the cable within 12 inches of the box and every 4.5 feet thereafter. The previous code language could technically allow an unlimited length of coiled up NM cable inside the wall as long as it was secured within 12 inches of the box.
In the 2020 NEC®, no more than 18 inches of cable length is allowed between the cable entry to the box and the closest cable support (see image).
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC® edition of NFPA 70.
2017 Code Language:
334.30 Securing and Supporting. Nonmetallic-sheathed cable shall be supported and secured by staples; cable ties listed and identified for securement and support; or straps, hangers, or similar fittings designed and installed so as not to damage the cable, at intervals not exceeding 1.4 m (4 ½ ft) and within 300 mm (12 in.) of every cable entry into enclosures such as outlet boxes, junction boxes, cabinets, or fittings. Flat cables shall not be stapled on edge.
2020 Code Language:
334.30 Securing and Supporting. Nonmetallic-sheathed cable shall be supported and secured by staples, cable ties listed and identified for securement and support, or straps, hangers, or similar fittings designed and installed so as not to damage the cable, at intervals not exceeding 1.4 m (4 ½ ft) and within 300 mm (12 in.) of every cable entry into enclosures such as outlet boxes, junction boxes, cabinets, or fittings. The cable length between the cable entry and the closest cable support shall not exceed 450 mm (18 in.). Flat cables shall not be stapled on edge.