What is BX Cable?

Understanding BX Cable

BX Cableis a trade name used by many electricians. It means armored electrical cable. The cable contains insulated copper conductors inside a flexible, spiral-wound metal sheath. The sheath resists impact, abrasion, and some damage from fasteners. Current code language identifies many BX products.Type AC cable.

Related glossary terms: Conduit, Electrical Grounding, National Electrical Code.

BX Cable isn't one single product specification. Older cable, modern Type AC cable, and metal-clad cable can look similar. They can have different construction and grounding rules. A typical assembly may include insulated hot conductors, a neutral conductor, and metal armor. It may also include a bonding strip or bonding means. The cable marking, conductor count, fittings, and listing control installation.

How BX Cable Works, Is Measured, or Is Used?

The metal armor forms a flexible protective pathway around the conductors. Installers cut the armor with a cable cutter. They protect the conductor insulation at the cut. They attach an approved armored cable connector to an electrical box or enclosure. The connector must match the cable type and size. A loose connector can leave wiring unsupported. It can also interrupt the intended grounding path.

Electricians identify BX Cable by its conductor size and number. They also check the cable type and ampacity. Wire gauge describes conductor size. Ampacity describes the current conductors can carry under stated conditions. The circuit breaker and insulation rating affect the permitted load. Ambient temperature and current-carrying conductors also affect the load. Armor alone doesn't determine the cable's electrical rating.

During installation, workers route the cable without sharp bends. They secure it near boxes. They protect it from conditions that could damage the armor or insulation. A short piece called an anti-short bushing may be required at armor ends. This depends on the cable construction and applicable rules. The installer checks conductor connections, box fill, and grounding continuity. The installer also checks circuit breaker protection.

Why BX Cable Matters?

Armored cable can protect wiring where a nonmetallic jacket faces greater physical risk. Examples include exposed basement wiring and commercial interiors. Other examples include masonry surfaces and tight locations. Rigid conduit might take more space or labor in these locations. Its metal covering can also protect wiring during remodeling. This metal path creates bonding and installation questions. These questions don't arise in the same way with nonmetallic cable.

Incorrect fittings or damaged armor can create a shock hazard. They can also cause a short circuit. They may create an unreliable equipment grounding path. An installer must confirm that the cable, connector, and box work together. The grounding method must also work with this listed system.National Electrical Code sets installation rules. Local authorities may use adopted editions and amendments during inspection.

When BX Cable Matters Most?

BX Cable needs close review during repairs in older buildings. Visible armor may not show the cable's actual construction. Some older systems have brittle insulation or missing bonding parts. They may also have loose fittings or poor connections inside crowded boxes. A visual inspection can reveal damage. A continuity test may also be needed. Careful checks of terminations can assess the grounding path.

The cable choice also matters during remodels and service changes. It matters for new circuits, too. Compare the cable listing with the planned environment and circuit load. Check support spacing, box type, and local code needs. In Fort Wayne, Indiana, an electrical inspection may check proper fittings. It may also check grounding and protection from damage. Inspectors may check compliance with the code edition adopted for the project.