How to Lock Out a Breaker Using a Circuit Breaker Lockout Device

Electrical workers who service circuit breakers face serious hazards, including electric shock, arc flash, and circuit overloads. These risks often stem from skipped safety procedures, particularly failure to follow proper lockout tagout procedures.

In 2020 alone, the National Fire Protection Association (NFPA) reported 126 fatalities and 2,380 non-fatal injuries due to electrical exposure. These figures underscore the importance of strictly following established safety practices. One of the most effective ways to prevent accidental re-energization during maintenance is by locking out the circuit breaker. This ensures it cannot be turned back on, either accidentally or intentionally, while servicing or maintenance work is in progress.

So, how do you properly lock out a circuit breaker and install a breaker lock device?

Key Takeaways

• Breaker lockout is essential to comply with OSHA's Lockout/Tagout (LOTO) regulations, preventing energy-related accidents during servicing or maintenance.

• Locking out a breaker ensures electrical equipment stays off during maintenance, avoiding sudden energization that can lead to injury or damage.

• Knowing various circuit breaker types helps in selecting the proper breaker lock device, ensuring secure and effective isolation of electrical energy sources.

• Verifying lockout success using voltage testers is a key step in LOTOTO, confirming no residual energy is present before maintenance begins.

What Is a Circuit Breaker and How Does It Work?

A circuit breaker is an electrical switch designed to automatically stop the flow of electricity when a fault, such as an overload or short circuit, occurs. Breakers are installed in electrical panels, where they connect the main bus bars to the individual circuit wires that distribute power throughout the electrical system. Each breaker monitors the electrical current flowing through its circuit. If the current exceeds safe levels, the breaker "trips" and opens the circuit to stop the flow of electricity.

Traditional circuit breakers are mechanical switches that operate with a spring-loaded mechanism and a thermal or magnetic trip unit to detect faults and disconnect power. Modern circuit breakers, on the other hand, often include electronic trip units and more precise sensors. These allow for faster response times and better coordination with complex electrical systems.

Circuit Breakers vs. Fuses vs. Disconnects

Circuit breakers, fuses, and disconnects are all devices used to control and protect electrical circuits, but they work differently:

• • Circuit Breakers
    • Automatically trip to stop power during an overload or short circuit.
    • Can be reset after the fault is cleared.
    • Commonly used for ongoing circuit protection and easy restoration.
  • Fuses
    • Contain a metal wire that melts when overloaded, permanently breaking the circuit.
    • Must be replaced once blown.
    • Provide simple, one-time overcurrent protection.
  • Disconnects (Safety Switches)
    • Manually isolate equipment from the power source.
    • Do not trip automatically.
    • Used for maintenance or emergencies to provide a visible break in the circuit.

Types of Circuit Breakers

How to Lock Out a Breaker?

OSHA 29 CFR 1910.147(a)(3)(i) standard requires “employers to establish a program and utilize procedures for affixing appropriate lockout devices or tagout devices to energy isolating devices, and to otherwise disable machines or equipment to prevent unexpected energization, start-up or release of stored energy in order to prevent injury to employees.”

A circuit breaker lock is a lockout tagout device that prevents unexpected electricity re-energization by keeping circuit breakers in the OFF position. During electrical equipment repair, the power source should be turned off and kept that way until the repair work is done.

Since breaker designs vary, choosing the correct breaker lockout device matters. Be sure to check out our Breaker Lock Solution Guidelines to find the right TRADESAFE Breaker Lockout Device for your specific breaker model and number of poles.

How to Install a Breaker Lock?

Now that you know the requirements for locking out a circuit breaker, the next step is learning how to install the breaker lockout device. In the sections below, we’ll walk through step-by-step instructions for installing the most commonly used breaker locks:

Clamp-On Breaker Lockout Devices

A clamp-on circuit breaker lockout is available in different sizes to accommodate medium to oversized circuit breakers without lockout holes in the toggle switch. Follow these steps for a proper clamp-on circuit breaker lockout installation:

1. Put the circuit breaker in the OFF position.

2. Place the clamp-on circuit breaker lockout device over the circuit breaker switch toggle.

3. Rotate the thumb wheel clockwise to secure the lockout device.

4. Close the lid and attach a lockout tagout padlock and tag to secure the lockout.

Universal Circuit Breaker Lockout Devices

A multi-pole universal circuit breaker lockout device is designed to lock out most single and multi-pole circuit breakers. This outlines the safe installation procedure for a universal multi-pole circuit breaker lockout:

1. Put the circuit breaker in the OFF position.

2. Attach the lockout device to the breaker switch (the universal breaker lockout device will easily lock out single and multiple-handle circuit breakers).

3. Place the device over the switch and lock the switch in the OFF position.

4. Slip the padlock shackle through one of the open holes in the top of the device, then attach the protective tag.

Miniature Circuit Breaker Pin Lockout Devices

A mini circuit breaker lockout is a device used for securing miniature circuit breakers in the OFF position. Installing Pin-In-Standard, Pin-Outward, and Pin-Out-Standard lockout devices follows the same basic process below. What changes is simply which device fits based on the type of breaker toggle you're locking out.

1. Put the mini circuit breaker in the OFF position.

2. Push the lockout device button to disengage the pins.

3. Position the pins into the small holes of the casing, then release the push button.

4. Attach a lockout tagout padlock through the lockout device hole to complete the lockout.

Tie Bar Lockout Devices

A tie bar lockout device is specifically affixed to multi-pole breakers that have tie bars connecting two or more toggles. To install it correctly, here’s what you need to do:

1. Place the mini circuit breaker in the OFF position.

2. Position the metal clip under the tie bar and between the poles.

3. Rotate the thumb wheel clockwise to secure the lockout device onto the circuit breaker.

4. Insert a TRADESAFE padlock through the hole to secure the device in the locked position.

Breaker Blocker Kit

A breaker blocker kit is a versatile lockout tagout system that uses adhesive-backed breaker blockers and interchangeable blocker arms. It is a good solution for switches that are oddly shaped or too large for standard breaker lockout devices. Here’s how to set it up the right way:

1. Shut off the circuit breaker.

2. Clean the area around the breaker thoroughly (breaker blockers usually need a clean surface to adhere properly).

3. Stick the base plate of the breaker blocker onto the panel or near the breaker using its adhesive backing.

4. Attach the blocker arm over the breaker toggle.

5. Some versions use a cover or locking plate that clicks into place over the blocker arm.

6. Insert a padlock through the designed holes to keep the blocker locked over the toggle, preventing reactivation.

Common Mistakes in Using Breaker LOTO Devices and How to Avoid Them

In the lockout tagout of circuit breakers, one common mistake is not fully engaging the breaker lock device’s mechanism. I once visited a manufacturing facility where the authorized employee applied a breaker thumb-screwed type lockout device, but didn’t tighten it securely. It slipped off when the panel was bumped, leaving the breaker off but unlocked.

This confused some workers who thought the circuit was back in service, while others believed it was still under maintenance. Luckily, no one was hurt, but it was a close call that led to a retraining session for the entire crew.

Another frequent error is using the wrong lockout device for the type of breaker. If the wrong type is used, the breaker handle might not be fully restrained, which gives a false sense of security and defeats the entire purpose of the lockout. Remember, the right lockout device depends on the type of breaker, the toggle style, and the environment you're working in.

How to Ensure a Successful Lockout

In addition to avoiding common mistakes when using breaker LOTO devices, authorized employees must perform a lockout tagout tryout (LOTOTO) to confirm the panel is in a zero energy state. This step is essential to confirm that the breaker lockout tagout is fully effective and the equipment is safe to work on.

I've seen workers skip voltage verification after applying the lockout device. Some assume that once the breaker is turned off and locked, the circuit is safe, especially if the panel is labeled. In reality, labeling can be inaccurate, or the wrong breaker may have been locked out, leaving the circuit still energized. In other cases, teams rush to complete the task and see voltage testing as an extra step rather than a requirement.

Expert Insights

“In my experience, the only safe way to test that electrical equipment is safe to work on is using a voltage indicator, in conjunction with a proving unit, before and after testing for dead, to prove the voltage indicator is working correctly. Non-contact devices, such as volt sticks or pens, cannot be relied upon for this purpose. If you’re going to put tools or your hands on any electrical equipment, you need to be absolutely certain it’s safe to work on before you touch it…” — Mark Platten, a Commissioning, Compliance & COHE Manager with over 35 years’ experience, shared his thoughts on “What are the Most Effective Ways to Verify Electrical Lockout and Tagout Procedures?”

Breaker LOTO Installation FAQs

How do you disable a breaker?

To disable a breaker, switch it to the OFF position and apply a properly rated breaker lockout device to prevent it from being turned back on. Follow your facility’s lock out tag out circuit breaker procedure, including tagging the breaker and verifying zero voltage before starting any work.

How to unlock a breaker lock?

Only the person who applied the lock should remove it. To unlock, remove the padlock and tag, then take off the breaker lockout device. This should only be done after the work is complete, and it’s been confirmed that it’s safe to re-energize the equipment.

Can one lockout device fit all breakers?

No. Lockout devices must match the specific type and size of the breaker. For example, miniature circuit breakers often require pin-in or pin-out devices, while multi pole breakers with a tie bar need a tie bar lockout. Using the wrong device may fail to secure the breaker properly, compromising safety.

Is it OSHA compliant to use non-branded lockout devices?

OSHA does not require lockout devices to be from a specific brand. However, the devices must be durable, standardized, and capable of effectively preventing energy release. Non-branded devices are acceptable as long as they meet these criteria and are used correctly.

What happens if I skip installing a lockout device during repairs?

Skipping the installation of a breaker lockout device is a serious safety violation. It leaves the breaker vulnerable to accidental re-energization, which can cause electrical shock, arc flash, or even fatal injuries. It also puts your facility at risk of non-compliance with OSHA’s lockout tagout standards.