---
title: "What Is NM-B cable? Electrical Glossary | Daniel Electric"
description: "NM-B is nonmetallic-sheathed cable: insulated wires inside a plastic jacket, widely used for wiring inside homes."
url: https://danielelectric.multisites.ai/glossary/nm-b-cable
publisher: Daniel Electric
phone: +1-817-481-8606
quote: https://danielelectric.multisites.ai/contact
---

Wiring and circuits

# NM-B cable

NM-B is nonmetallic-sheathed cable: insulated wires inside a plastic jacket, widely used for wiring inside homes.

OSHA describes nonmetallic-sheathed cable as a factory assembly of two or more insulated conductors with an outer sheath of moisture resistant, flame-retardant, nonmetallic material. Southwire says the conductor insulation in NM-B is rated 90 degrees C, and the cable is primarily used for residential branch circuits.

[Romex](https://danielelectric.multisites.ai/glossary/romex) is the brand name most people use for it. The cable runs through framing in dry spots. Sizes follow [wire gauge](https://danielelectric.multisites.ai/glossary/wire-gauge). Damaged, pinched or overheated cable is a fire risk. Have a licensed electrician check it. See [electrical warning signs](https://danielelectric.multisites.ai/guides/electrical-warning-signs).

[Daniel Electric can helpResidential electrician](https://danielelectric.multisites.ai/electrician)

## Related terms

-   [Romex](https://danielelectric.multisites.ai/glossary/romex)
-   [Wire gauge](https://danielelectric.multisites.ai/glossary/wire-gauge)
-   [Copper wiring](https://danielelectric.multisites.ai/glossary/copper-wiring)
-   [Junction box](https://danielelectric.multisites.ai/glossary/junction-box)

## Sources

1.  [OSHA: 1910.399 Definitions applicable to this subpart](https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.399)
2.  [Southwire: Romex Brand SIMpull Copper Type NM-B Cable](https://www.southwire.com/wire-cable/building-wire/romex-sup-sup-brand-simpull-sup-sup-copper-type-nm-b-cable/p/63968202)

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