How Safe is Low Voltage?

 In 2023, Tip of the Week

A gardener was working near a small outside, detached building. He was fixing a leaking underground pipe supplying water to a sprinkler system, and there was water in the hole he was making under the building. At some point, the gardener contacted the building, which was not properly grounded, fatally electrocuting himself. Everyone at the site had assumed that the electrical system in the building had been shut off. It had not. The electricity in that building was a standard household current of 110 volts, considered to be “low voltage” by some definitions.

There is a commonly held myth that low voltage is not harmful. But that depends on your definition of the term. Many of us, including some safety professionals, sometimes refer to low voltage lines as those that supply power to alarm and detection systems, sound systems, and which charge the battery on your computer or phone. This is one use of the term, but it does not align with the definitions found in regulations. Both the National Electrical Code (NEC) andOSHA define low voltage as being any electrical system that is under 600 volts.The gardener in our true story above was electrocuted at 110 volts.

Not only can low voltages be harmful, but they can also be fatal. Read what the physics department at the Ohio StateUniversity published:

“Individuals have been electrocuted by appliances using ordinary house appliances using currents of 110 volts and by electrical apparatus in industry using 42 volts direct current…. From a practical viewpoint, after a person is knocked out by an electrical shock, it is impossible to tell how much current has passed through the vital organs of his body. Artificial respiration [CPR] must be applied immediately if breathing has stopped.” To see the full quote, follow this link:

The Fatal Current

In addition to being potentially fatal, low voltage burns can cause debilitating injuries. Sometimes the burns are not external, to the layers of skin, but the burns occur internally, as seen in the quote from the Ohio State University. So, the potential for shocks from even low voltage systems can cause serious harm including causing a sudden cardiac arrest. As safety professionals, we need to have abetter understanding of the term “low voltage” as it is used in codes and regulations.

So, to apply these concepts, you should look around your office, workplace, or home and review the electrical supply systems that are present. Are there small wires that are exposed and not enclosed in conduit providing power to a very low voltage system that powers the alarm system or which charges your computer? These systems generally have a voltage reducer or transformer to take the voltage down to low levels such as 24 volts that generally do not cause harm when an exposure occurs. Is there something that you would call a “low voltage system”as the definition listed above? Often, these systems are plugged directly into wall outlets and directly power the equipment with voltages up to 600 volts.What is the electrical source there? Is it 110 volts? Yes. And as we just read, 110 volts can irreversibly harm you.

What is the lesson to learn here? Use your six-step lock-out/tag-out (LOTO) process every time you work on any electrical system. We think a very important part of the process is to verify the equipment is totally de-energized before starting to work on it. If unplugging the equipment removes the electrical source, consider capping the plug or disabling it somehow to prevent a helpful coworker from plugging it back in while you work on the equipment.

If the system is more complex, follow the LOTO steps faithfully. If you are unsure of the six steps, or would like to be trained on LOTO, we can recommend our online course, linked here:

LOTO Course

Weekly Discussion Challenge:

What are the six steps of LOTO? Can you list them in order?

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