How Do You Cut Armored Cable?
Mastering the art of cutting armored cable, or AC cable, involves selecting the right tools and employing safe techniques to ensure a clean, professional, and code-compliant installation. How do you cut armored cable? You primarily use a cable cutter, hacksaw, or rotary tool combined with techniques to protect the internal wires from damage.
Armored Cable: A Robust Wiring Solution
Armored cable (AC), often referred to as BX cable, provides a durable and flexible wiring method, especially in environments where wiring might be exposed to physical damage. Understanding its structure and the proper cutting techniques is crucial for any electrician or DIY enthusiast.
Why Use Armored Cable?
Armored cable offers several advantages over other wiring methods:
- Physical Protection: The interlocking metal sheath protects conductors from impacts, abrasion, and pests.
- Flexibility: AC cable can be bent and routed around obstacles more easily than rigid conduit.
- Simplified Installation: In many cases, AC cable can be installed without conduit, saving time and materials.
- Grounding Path: The metal armor often serves as a grounding path (depending on the installation and local codes).
Essential Tools for Cutting Armored Cable
- Cable Cutter (Rotary): This specialized tool scores the armor without damaging the wires. It is the preferred method for most professionals.
- Hacksaw: A traditional option, but requires more care and a steady hand to avoid cutting into the conductors.
- Rotary Tool (e.g., Dremel): Can be used with a cutting wheel, but requires extreme caution and safety measures.
- Lineman’s Pliers/Diagonal Cutters: For trimming the cut edge of the armor.
- Screwdriver: For prying open the armor to remove the cut section.
- Measuring Tape: To measure the cable length accurately.
- Safety Glasses: Always protect your eyes.
- Gloves: Recommended for hand protection.
The Cutting Process: Step-by-Step Guide
The safest and most effective way to cut armored cable is with a cable cutter. Here’s a detailed breakdown:
- Measure and Mark: Determine the required cable length and mark the cutting point clearly.
- Using a Cable Cutter: Place the cable cutter around the armor at the marked location.
- Rotate the Cutter: Rotate the cable cutter around the cable, applying light pressure. The cutter will score the armor.
- Bend and Separate: Once scored, bend the cable back and forth at the scored point. The armor should separate along the score line.
- Remove the Cut Section: Use a screwdriver or pliers to carefully pry open the cut armor.
- Inspect the Wires: Visually inspect the conductors for any damage. If damage is present, cut back the cable further.
- Install an Anti-Short Bushing (Redhead): This plastic bushing is essential. It protects the wires from the sharp edges of the armor where the cable enters a junction box.
- Secure the Connector: Install the appropriate connector according to local codes and the manufacturer’s instructions.
Cutting with a Hacksaw (Alternative Method)
While a cable cutter is preferable, a hacksaw can be used if necessary:
- Measure and Mark: Same as above.
- Score the Armor: Use the hacksaw blade to carefully score the armor, avoiding deep cuts that could reach the wires.
- Gradually Cut Through: Continue sawing slowly and carefully, rotating the cable as you go.
- Remove the Cut Section: Same as above.
- Inspect the Wires: Same as above.
- Install an Anti-Short Bushing (Redhead): This is even more crucial when using a hacksaw due to the increased risk of sharp edges.
- Secure the Connector: Same as above.
Common Mistakes to Avoid When Cutting Armored Cable
- Damaging the Conductors: The most common mistake is nicking or cutting the insulation of the wires inside the armor.
- Skipping the Anti-Short Bushing: This is a code violation and a safety hazard. Never omit this step.
- Using Dull Blades: Dull blades require more force, increasing the risk of slippage and damage.
- Rushing the Process: Take your time and be meticulous to avoid mistakes.
- Improper Grounding: Ensure the armor is properly grounded according to local codes.
Comparing Cutting Methods
| Method | Pros | Cons | Skill Level | Safety |
|---|---|---|---|---|
| Cable Cutter | Clean cut, minimal risk of wire damage, fast. | Requires specialized tool. | Beginner | High |
| Hacksaw | Readily available, inexpensive. | Higher risk of wire damage, requires more skill and patience. | Intermediate | Medium |
| Rotary Tool | Can be quick, useful in tight spaces. | Highest risk of wire damage, requires extreme caution and experience. | Advanced | Low |
Frequently Asked Questions (FAQs)
Can I use regular wire strippers to strip the wires inside armored cable?
No, using regular wire strippers directly on the wires inside armored cable is generally not recommended. The limited space and potential for damage to the insulation due to the metal armor require more careful handling. Instead, gently pull the wire out slightly beyond the cut armor and then use the strippers, being extra cautious not to damage the surrounding insulation.
Do I need to ground armored cable?
Yes, in most cases, armored cable does require grounding. The metal armor can serve as an equipment grounding conductor, but it’s crucial to ensure a proper connection at both ends of the cable run. Local electrical codes dictate the specific grounding requirements. Always consult with local regulations and/or a qualified electrician.
What is an anti-short bushing (redhead) and why is it important?
An anti-short bushing, often called a “redhead” due to its typical red color, is a small plastic bushing inserted between the cut end of the armored cable and the wires inside. Its purpose is to protect the wire insulation from the sharp edges of the armor, preventing short circuits and potential fire hazards. It is a code requirement in almost all jurisdictions.
What happens if I damage the wires inside the armored cable while cutting it?
If you damage the insulation of the wires, or worse, the conductors themselves, you should cut back the cable to a point where the wires are undamaged. Damaged wires present a serious electrical hazard. Never splice wires within armored cable.
Can I reuse armored cable?
Reusing armored cable is generally not recommended unless you are absolutely certain of its condition and history. If the cable is damaged, corroded, or of unknown origin, it should be discarded. Using new cable is the safest and most reliable option.
What size armored cable do I need for a specific circuit?
The appropriate size of armored cable depends on the amperage of the circuit and the type of load. Consult the National Electrical Code (NEC) or local electrical codes for specific requirements. It is always best to err on the side of caution and use a slightly larger size than required.
How do I connect armored cable to a junction box?
Armored cable is connected to a junction box using a specialized connector designed for AC cable. These connectors grip the armor and provide a secure and grounded connection to the box. Follow the manufacturer’s instructions carefully when installing the connector.
Is armored cable suitable for outdoor use?
Armored cable is generally not suitable for direct burial or wet locations unless it is specifically rated for those environments. Look for AC cable with a moisture-resistant jacket if outdoor use is required.
Can I run armored cable through a wall?
Yes, armored cable can be run through walls. However, it must be protected from physical damage, especially where it passes through studs or other framing members. Use nail plates or other protective devices to prevent nails or screws from penetrating the cable.
How far apart should I support armored cable runs?
The NEC specifies the maximum spacing for supporting armored cable runs. Generally, it should be supported every 4.5 feet horizontally and within 12 inches of any box or fitting.
What’s the difference between AC and MC cable?
AC (Armored Cable) typically has a bonding strip to aid in grounding, while MC (Metal-Clad) cable includes an insulated grounding conductor. MC cable offers a more robust grounding path and is often preferred in commercial and industrial applications.
How do I know if the armored cable is properly grounded?
The easiest way to verify proper grounding is to use a multimeter or circuit tester to check for continuity between the metal armor and a known ground point. Consult with a qualified electrician if you are unsure how to perform this test safely.