In the field of electrical installations, BX cable is a cornerstone for efficiently supplying power and signaling within buildings and structures. This flexible cable, durable and versatile has been a mainstay in the industry for decades, providing a solid solution for cabling needs in various sectors. Our goal is to delve deeper into the complexities of the BX cable, its uses, benefits and why it remains a preferred choice for electrical professionals.
What is BX Cable?
The BX cable, also known as shielded cable, is a type of electrical cable composed of wires enclosed within a flexible metal conduit. This conduit, usually made of galvanized steel or aluminum, offers protection to internal cables from physical damage, humidity and other environmental factors. BX cable design allows for easy bending and handling in corners and tight spaces, making it ideal for a wide range of installation applications.
BX cable is typically used in commercial and industrial environments, as well as in some residential applications. It is especially suitable for wiring in buildings where flexibility and durability are paramount. The metal conduit acts as a grounding conductor, adding an extra layer of safety and electrical code compliance.
Structure and characteristics of the BX Cable
BX Cable Components
The BX cable consists of the following components:
Metal cover: the outer armor, usually made of steel or aluminum, provides mechanical protection and acts as a grounding path.
insulated conductors: Internal cables are insulated to prevent short circuits and ensure safe electrical conduction.
paper wrapping (optional): some BX cables include a paper wrap for additional insulation.
Main features
Durability: metal casing offers high resistance to physical damage, making the BX cable ideal for wear-prone environments.
Fire resistance: armor provides an additional layer of protection against fire hazards.
Grounding Capability: the metal casing can serve as a grounding conductor, which simplifies installation.
BX Cable, AC Cable
| Driver size (AWG) | Solid or braided | Aluminum bonding wire size (AWG) | Interlocking galvanized steel | Amperage (amps) | |||
| External diameter (inches) | Weight (pounds/1000 feet) | 60 | 75 | 90 | |||
| 14/2 | solid | 16 sol | 0.464 | 86 | 15 | 15 | 15 |
| 14/3 | solid | 16 sol | 0.484 | 105 | 15 | 15 | 15 |
| 14/4 | solid | 16 sol | 0.517 | 126 | 15 | 15 | 15 |
| 12/2 | solid | 16 sol | 0.498 | 107 | 20 | 20 | 20 |
| 12/3 | solid | 16 sol | 0.521 | 134 | 20 | 20 | 20 |
| 12/4 | solid | 16 sol | 0.557 | 163 | 20 | 20 | 20 |
| 10/2 | solid | 16 sol | 0.56 | 142 | 30 | 30 | 30 |
| 10/3 | solid | 16 sol | 0.588 | 184 | 30 | 30 | 30 |
| 10/4 | solid | 16 sol | 0.632 | 228 | 30 | 30 | 30 |
| 8/2 | stranded | 16 sol | 0.686 | 211 | 40 | 50 | 55 |
| 8/3 | stranded | 16 sol | 0.749 | 311 | 40 | 50 | 55 |
| 8/4 | stranded | 16 sol | 0.81 | 387 | 40 | 50 | 55 |
| 6/2 | stranded | 16 sol | 0.783 | 318 | 55 | 65 | 75 |
| 6/3 | stranded | 16 sol | 0.827 | 424 | 55 | 65 | 75 |
| 6/4 | stranded | 16 sol | 0.896 | 535 | 55 | 65 | 75 |
| 4/3 | stranded | 16 sol | 1.095 | 625 | 70 | 85 | 95 |
| 4/4 | stranded | 16 sol | 1.15 | 797 | 70 | 85 | 95 |
| 3/3 | stranded | 16 sol | 1.175 | 746 | 85 | 100 | 110 |
| 3/4 | stranded | 16 sol | 1.244 | 1003 | 85 | 100 | 110 |
| 2/3 | stranded | 16 sol | 1.19 | 898 | 95 | 115 | 130 |
| 2/4 | stranded | 16 sol | 1.31 | 1155 | 95 | 115 | 130 |
BX Cable Applications
Residential Use
BX cable is commonly used in homes for:
- Connecting electrical appliances
- Wiring in basements and attics where added protection is needed
- Running circuits inside walls and ceilings
Commercial Applications
In commercial settings, BX cable is preferred for:
- Office building wiring
- Electrical installations in retail spaces
- Areas requiring enhanced fire resistance and durability
Industrial Applications
Industries rely on BX cable for:
- Machinery wiring
- Power distribution in factories
- Environments exposed to vibrations or mechanical stress
Advantages and disadvantages of BX cable
Advantages
Enhanced protection: Metal sleeve protects internal cables from physical damage.
Fire safety: Its fire resistant properties make it suitable for high risk environments.
Versatility: can be used in a variety of environments, from residential to industrial.
Grounding functionality: sleeve often eliminates the need for an additional ground wire.
Disadvantages
Installation complexity: Cutting and bending BX cable requires specialized tools and skills.
Higher cost: BX cable is more expensive than unshielded cables like NM cable (non-metallic).
Limited flexibility: Rigid metal case can be difficult to maneuver in tight spaces.
Installation Tips for the BX Cable
Tools needed
cable cutter
Shielded wire strippers
Screwdrivers
Protective gloves
Installation steps
Measure and cut: Use a cable cutter to cut the cable to the desired length.
Peel the armor: use a shielded wire stripper to remove the metal covering, leaving the insulated wires exposed.
Connect the cables: Attach conductors to appropriate terminals in electrical box.
Secure the cable: use clamps to secure the BX cable in place, making sure it doesn't move or come loose.
Safety tips
Always turn off the power supply before handling electrical cables.
Wear protective gloves to avoid injury from the sharp edges of the metal cover..
Recheck all connections to ensure proper grounding.
BX Cable vs. MC Cable
Both BX and MC cables are types of shielded cables used in electrical systems, but they have some key differences:
Structure: BX cables typically have a layer of rubber insulation and a metal jacket that provides additional protection. MC cables, on the other hand, They have thermoplastic insulation and a metal conduit that serves as both armor and a grounding path.
Applications: BX cables are often used in lower voltage applications where flexibility and cold resistance are important. MC cables are most commonly used in higher voltage applications or in situations where additional mechanical protection is needed.
Cost: MC cables can be more expensive than BX cables due to their thicker insulation and conduit.
How to cut a BX cable?
Cutting a BX cable requires special tools and techniques to ensure safety and accuracy. These are some steps to follow:
Prepare the tools: gather the necessary tools, including a cable cutter designed specifically for shielded cables, wire strippers and electrical tape.
Identify the cable: make sure you have identified the correct wire to cut and that it is safe to do so (For example, if the power is off).
Measure and mark: Measure the length of wire you need and mark the cutting point with a marker or tape.
cut the cable: use the wire cutter to make a clean, straight cut through the armor and insulation. Be careful not to damage the internal conductor.
Strip insulation: use wire strippers to remove insulation from the end of the wire, exposing the inner conductor.
How to ground a BX cable?
Grounding the BX cable is crucial for safety and to ensure proper operation of the electrical system. These are some steps to follow:
Identify the grounding conductor: BX cables generally have a grounding conductor (often a green or bare copper wire) which must be connected to the grounding system.
Prepare the grounding system: Make sure the grounding system (For example, grounding clamp, grounding rod) is properly installed and in good condition.
Connect the grounding conductor: use a suitable connector (For example, a grounding clamp) to connect the grounding conductor to the grounding system. Make sure the connection is tight and secure.
Test ground connection: use a ground tester to verify that the ground connection is effective and meets local electrical code requirements.
It is important to note that electrical work should always be performed by qualified electricians who are familiar with local electrical codes and safety regulations..
BX cable installation and maintenance
Installation and maintenance of BX cable requires specific knowledge and skills to ensure the electrical system operates safely and efficiently.. Next, Some key considerations for installation and maintenance are included:
Installation:
Ensure that the BX cable is routed through suitable conduits or boxes to protect it from physical damage and moisture..
Use approved fastening devices to secure the cable at intervals along its length, making sure it doesn't sag or loosen.
Follow local electrical codes and standards for grounding and bonding of BX cable.
Use proper cutting tools and techniques, strip and terminate the cable, making sure connections are secure and reliable.
Inspection and testing:
Regularly inspect the BX cable for signs of damage, like cracks, corrosion or exposed conductors.
Test the electrical continuity of the grounding conductor to ensure it is working properly.
Check for overheating or arcing inside the conduit, which may indicate a problem with the circuit or cable.
Maintenance:
Keep the area around the BX cable clean and free of debris, which can cause overheating or short circuits.
Replace any damaged sections of cable immediately to avoid potential hazards.
Periodically inspect fasteners and conduit for signs of wear or damage, and replace them as necessary.
Troubleshooting:
If you suspect an electrical problem, use the appropriate test equipment to diagnose the problem.
Follow the manufacturer's instructions and local electrical codes to troubleshoot and repair the BX cable..
If the problem is beyond the scope of your experience, consult a qualified electrical contractor or technician.