Remove a Knock Out From An Electrical Box: A Step-by-Step Guide to a Safer and More Functional Installation
Dealing with an electrical box renovation or installation often involves wrestling with those stubborn metal circles known as knockouts. These pre-scored openings are designed for easy removal, allowing for the passage of electrical conduit or cable. However, sometimes they don’t cooperate, or the tools available might not be ideal. Fortunately, learning to remove a knock out from an electrical box is a straightforward process that, with the right approach, can be done safely and efficiently. This article will guide you through the essential techniques, necessary tools, and crucial safety precautions to ensure a clean and professional finish to your electrical work.
Understanding the Purpose of Electrical Box Knockouts
Before we dive into the removal process, it’s helpful to understand what knockouts are and why they exist. Electrical boxes, whether they are junction boxes, outlet boxes, or switch boxes, need a way for wires to enter and exit. Knockouts are precisely engineered to provide these entry points. They are typically thin, pre-scored metal discs that can be pushed inward and then broken off. This design offers flexibility, allowing electricians to choose the exact knockout needed based on the number and type of cables or conduits being run into the box. They prevent the need for drilling at the job site, saving time and effort.
The Right Tools for the Job: Essential Equipment to Remove a Knock Out From An Electrical Box
While some knockouts can be loosened with a screwdriver and brute force, using the correct tools will make the job significantly easier and safer. Here are the primary tools you’ll likely need:
Pliers (Linesman or Groove Joint): These are your most versatile friends when it comes to tackling stubborn knockouts. Linesman pliers, with their flat crushing surface, are excellent for gripping and twisting. Groove joint pliers (like Channel Locks) offer a broader grip.
Screwdriver (Flathead): A sturdy flathead screwdriver can be used as a lever to pry or tap the knockout loose.
Hammer: A light tap from a hammer can often dislodge a knockout once it’s been loosened. Be cautious not to hit too hard and damage the box.
Wire Strippers/Cutters: Some newer tool designs integrate knockout punch mechanisms. Even if yours doesn’t, these are essential for any electrical work surrounding the box.
Knockout Punch Set (Optional but Recommended): For professionals or those who frequently work with electrical boxes, a dedicated knockout punch set is the most efficient and clean method. These sets typically include a die, punch, and draw stud that, when tightened, cleanly punch out the knockout.
Safety Glasses: This is non-negotiable. Metal shards can fly when removing knockouts, and protecting your eyes is paramount.
Work Gloves: These offer a better grip and protect your hands from sharp edges.
Step-by-Step: How to Remove a Knock Out From An Electrical Box
The method for removing a knockout can vary slightly depending on its size, the material of the box, and how well it was manufactured. However, these general steps will apply to most situations:
1. Identify the Knockout: Locate the knockout you need to remove. They are usually arranged around the perimeter of the box.
2. Loosen the Knockout:
Using Pliers: Grip the edge of the knockout firmly with your pliers. Twist the knockout back and forth. The goal is to break the scored line. You might hear a slight crack or feel it loosen.
Using a Screwdriver: Insert the tip of a flathead screwdriver into the score line of the knockout. Gently tap the end of the screwdriver with a hammer. You can also try to use the screwdriver as a lever to pry the knockout inward.
3. Break Free the Knockout: Once loosened, you should be able to push the knockout inward with your pliers or screwdriver. If it doesn’t readily fall out, use your pliers to grip the edge and gently bend it further inward until it snaps off. Sometimes, you can simply pull it free with the pliers.
4. Remove Any Remaining Sharp Edges: After the main piece of the knockout is removed, inspect the opening. If there are any jagged edges or burrs, use your pliers to carefully bend and remove them. This is crucial for preventing damage to the electrical wires that will pass through.
5. Install a Cable Clamp or Connector: Once the knockout is cleanly removed, you must install a proper cable clamp or conduit connector. This fitting not only secures the cable or conduit to the box but also provides insulation for any sharp edges left within the opening, ensuring the safety of your electrical installation. These are typically threaded and tightened into the opening or snapped into place.
Safety First: Important Considerations When You Remove a Knock Out From An Electrical Box
Electrical work, even seemingly simple tasks like removing a knockout, carries inherent risks. Always prioritize safety:
Turn Off Power: Before you begin any work on an electrical box, always ensure the power to that circuit is turned off at the breaker panel. Test the wires with a voltage tester to confirm the power is indeed off.
Wear Safety Gear: As mentioned, safety glasses and work gloves are essential.
Inspect the Box: Check for any damage to the electrical box itself. A damaged box should be replaced.
Secure Cables Properly: Never leave wires exposed. Always use appropriate connectors and clamps to secure cables exiting the box.
Understand Local Codes: Electrical installations must comply with local building codes and regulations. If you are unsure, consult a qualified electrician.
Troubleshooting Stubborn Knockouts
Occasionally, you’ll encounter a knockout that is exceptionally resistant. Here are a few extra tips:
Gentle Tapping: Instead of forceful prying, try a series of gentle taps with a hammer on the edge of the knockout. Sometimes, this can gradually weaken the scored line.
Multiple Angles: Try applying pressure from different angles with your pliers or screwdriver.
Penetrating Oil (Use with extreme caution): For older, rusted boxes, a tiny amount of penetrating oil might help, but be very careful not to let it drip inside the box or onto electrical components. Ensure it’s completely cleaned off before proceeding.
Knockout Punch Tools: If you face this frequently, investing in a proper knockout punch set will save you significant time and frustration.
By following these steps and prioritizing safety, you can confidently remove a knock out from an electrical box, ensuring a secure, functional, and code-compliant electrical installation. Remember, when in doubt, always consult a professional electrician.