How to Use a Fish Tape: A Professional Guide for Electricians

Using a fish tape is a fundamental skill for any electrician, essential for routing wires through an electrical conduit. This guide provides a detailed, professional overview of how to use a fish tape effectively for a safe and efficient cable pull through. The process involves selecting the right tool—such as a flexible, non-conductive fish tape for energized areas or a rigid steel fish tape for long, straight runs—preparing the raceway, and attaching the wires securely. Proper technique, including the use of wire pulling lubricant and understanding concepts like pulling tension, ensures that conductors are not damaged during installation. Adhering to the National Electrical Code (NEC) for conduit fill limits is a critical first step before any wire is pulled into an electrical conduit, guaranteeing a compliant and safe installation.

Understanding Your Tools: Steel vs. Non-Conductive Fish Tapes

Selecting the correct fish tape is the first step toward a successful wire pull. The choice between materials directly impacts safety, efficiency, and the types of conduits you can navigate. There is a clear industry trend favoring advanced materials for enhanced safety and flexibility.

Steel Fish Tape

A steel fish tape is the traditional choice, known for its rigidity and strength. It excels in long, straight pulls through larger conduits like EMT conduit or RMC. Its stiffness allows it to be pushed considerable distances without buckling. However, its primary drawback is conductivity. A steel tape should never be used in or near panels, enclosures, or any raceway that may contain live circuits.

Non-Conductive Fish Tape

Modern fish tapes are often made from fiberglass or nylon. These are known as non-conductive fish tape models and offer a significant safety advantage. Key benefits include:

• Safety: Ideal for work in existing structures or conduits where de-energizing all circuits is not feasible.
• Flexibility: Superior for navigating conduits with multiple bends, such as in complex runs of PVC conduit or flexible metallic conduit.
• Memory: High-quality fiberglass tapes have less memory than steel, meaning they stay straighter when uncoiled.

Newer innovations even include powered fish tapes that automate the feeding and retracting process, significantly reducing physical strain and speeding up large-scale jobs. Some models now integrate digital screens for measuring distance, helping to locate blockages within a conduit run.

Pre-Pull Preparations: Ensuring a Smooth Cable Pull Through

Proper preparation is non-negotiable for a professional installation. Before you even unreel your fish tape, two key areas must be addressed: conduit fill and lubrication.

Calculating Conduit Fill

Overfilling a conduit is a direct violation of the National Electrical Code (NEC) and poses serious risks, including wire damage from excessive pulling tension and heat buildup. The maximum conduit fill percentage depends on the number of conductors in the raceway. For a comprehensive breakdown of these rules, you should reference our detailed conduit fill calculations NEC guide. Using a conduit fill calculator is the most reliable method to ensure compliance. These calculations are critical, as outlined in NEC Chapter 9, Table 1.

Call to Action: Before you pull, make sure your conduit fill is code-compliant.

Applying Wire Pulling Lubricant

For any pull other than a very short, straight run, wire pulling lubricant is essential. It dramatically reduces friction and the force required for the pull. According to research from the National Electrical Contractors Association (NECA), proper lubricant can reduce pulling tension by 35% to 60%, preventing damage to the wire insulation of conductors like THHN wire. Apply the lubricant generously to the wires as they enter the conduit, ensuring complete coverage, especially at the pulling head.

Step-by-Step Guide: How to Use a Fish Tape

With preparations complete, you can begin the physical process of pulling wire. This requires precision and patience.

1. Feed the Fish Tape: Position yourself at one end of the electrical conduit. Unreel the fish tape and feed the leader end into the raceway opening. Push the tape through the conduit, using short, firm motions. If you encounter a bend or obstruction, you may need to pull back slightly and twist the tape to help the fish tape leader navigate the corner.
2. Attach the Wires: Once the end of the fish tape emerges from the other side of the conduit, it’s time to attach your conductors. For multiple wires, strip about 4-6 inches of the insulation off each one using a proper wire stripping tool. Stagger the wires by a few inches, loop the copper of the first wire through the eyelet of the fish tape leader, and twist it back on itself securely.
3. Create a Pulling Head: Wrap the subsequent wires around the first one, creating a staggered, tapered bundle. Use high-quality electrical tape to wrap the entire bundle, starting about an inch below the eyelet and extending several inches down the wires. This creates a smooth, cone-shaped pulling head that will glide through the conduit more easily. Ensure the tape is wrapped tightly to prevent snagging.
4. Pull the Conductors: One person should slowly and steadily pull the fish tape back through the conduit. A second person should be at the other end, feeding the stranded wire or solid conductors into the conduit and applying wire pulling lubricant. Communication is key to avoid binding and excessive tension.
5. Complete the Pull: Continue pulling with consistent force until the pulling head emerges. Pull enough extra wire through to comfortably make your connections at both ends, then cut the conductors from their spools.

Advanced Techniques and Considerations

For more challenging pulls, electricians use specialized equipment and techniques.

Using Mule Tape and a Pulling Head

For heavy pulls involving large conductors or long runs, a fish tape may only be the first step. Often, the fish tape is used to pull in a stronger pulling medium, such as mule tape (a high-tensile polyester pulling tape). The mule tape is then attached to the conductors using a mechanical pulling head, like a basket grip, which provides a more secure connection than electrical tape alone. This combination is standard practice for commercial and industrial electrical installations.

Managing Pulling Tension

Maximum pulling tensions are specified by cable manufacturers and standards bodies like the Insulated Cable Engineers Association (ICEA) to prevent stretching or damage. The NEC requires installers to follow these manufacturer and standards-based instructions per Article 110.3(B). For long or complex pulls, a dynamometer might be used to monitor the force. If tension becomes excessive, stop the pull. The issue could be a collapsed conduit, an unrecognized obstruction, or exceeding the NEC bend limitations (no more than 360 degrees of bends between pull points).

The type of conduit also plays a major role. Techniques for installing RMC conduit, for instance, differ from those for PVC. For detailed instructions on rigid steel, see our guide on installing RMC conduit. Similarly, there are specific 2023 NEC rules for PVC conduit use that impact installation and pulling strategies.

Key Takeaways for Safe and Compliant Wire Pulling

• Prioritize Safety: Always use a non-conductive fish tape when working near potentially energized circuits.
• Respect Conduit Fill Limits: Never exceed the maximum fill percentages outlined in the National Electrical Code (NEC).
• Lubricate Generously: Use an appropriate wire pulling lubricant to reduce friction and protect wire insulation.
• Communicate: Effective communication between the puller and the feeder is essential for a smooth and safe cable pull through.
• Use the Right Tools: For heavy pulls, upgrade from electrical tape to mule tape and a mechanical pulling head.

Primary Sources

• National Fire Protection Association (NFPA) for the National Electrical Code (NEC)
• Insulated Cable Engineers Association (ICEA)

Frequently Asked Questions (FAQ)

How do you use a fish tape in a conduit with multiple bends?

For conduits with several bends, a flexible non-conductive fish tape made of fiberglass or nylon is superior. Push the tape until you hit a bend, then pull back a few inches and twist the case while pushing forward to help the leader navigate the turn. Generous use of wire pulling lubricant on the tape itself can also help it slide through tight spots.

Can you use a fish tape to pull Romex wire?

While possible in short, straight sections, pulling Romex wire (Type NM cable) through a complete conduit system is generally not standard practice. However, it can be code-compliant under specific conditions. NEC 334.15 permits running NM cable in a raceway for physical protection against damage, such as where it is exposed. This is typically done in dry locations for short segments. For long runs, individual conductors are the correct choice. Per NEC Table 310.104(A), THHN wire is suitable for dry and damp locations, while THWN-rated conductors are required for wet locations, making dual-rated THHN/THWN a versatile option for most conduit installations.

What is the difference between a steel fish tape and a non-conductive fish tape?

A steel fish tape is highly rigid and strong, making it ideal for pushing long distances in straight runs of EMT conduit. However, it is electrically conductive and dangerous to use near live circuits. A non-conductive fish tape (fiberglass or nylon) is flexible, excellent for conduits with bends, and provides critical protection against electric shock, making it the safer choice for most renovation and service work.