High Voltage Safety

2024-11-20 | By Antonio Velasco

Working on my father’s BMW E36 as a kid brings back a lot of fond memories. He’d always open up the hood to explain each part of the engine and have me help him with the fuses, fluids, and lights. Yet, he’d always make sure to tell me to stay away from one specific part of the engine: the battery. He’d mention frequently how that component can become dangerous very quickly, and how handling it the wrong way could land me in the hospital.

A decade later, I’ve had to work frequently with high voltage components through UCI’s FSAE team and some IEEE labs and have since learned how to safely work with them. In this blog, I’ll talk about the ins and outs of high voltage safety and mention how you as a maker can remain safe while working on your projects.

What’s the Danger?

Electricity across the human body is especially dangerous as it can directly harm bodily functions and cause fatal injuries. The reason why this occurs is ironically because your body uses electricity as is. Multiple bodily systems, such as the nervous system, utilize charged ions to perform basic functions, such as extending or contracting muscles or even processing information in your brain. It even is the reason your heart can beat at a specific interval (hence why when your heart stops, they shock it with a very high amount of electricity through a defibrillator). Heart monitors, like that shown below, measure the electrical pulses through your heart to depict your heartbeat.

High Voltage Safety

Because of all this electrical function, your body is naturally a conductor of electricity. It’s not a great one though, and as you might’ve noticed from working on electronics, when a component resists or dissipates current, it does it in the form of heat. As such, similarly to how you can burn out components with too much current or voltage, the same can be said about your body. Muscles, nerves, and even your skin can be burnt out and cause serious, sometimes fatal, injuries. Electrical rhythms can be disturbed, and your muscles will involuntarily spasm.

This danger leads to thousands of injuries and deaths each year and should be taken very seriously.

How to Work Around High Voltages Safely

You may have heard that “it’s not the voltage that kills you, it’s the amperage.” While it’s true that the current (the high flow of electrons through your body) will essentially be the culprit, there needs to be sufficiently high voltage to create such a current. As such, we still refer to it as high voltage safety and not current safety. All it takes is just 10mA for there to be extreme pain, and 50mA to potentially be lethal. The following steps are good precautions to take to ensure that you and your peers stay safe:

Understand the Equipment Before Working on It: Know the voltages and the specifications behind your equipment. Understand where any exposed points may be and how to properly discharge the equipment. Use the equipment away from exposed metal (which can act as grounds). Make sure any test equipment is rated for the voltage/current that you will be testing. Warning stickers (like the one shown below) should be visible on any dangerous equipment. Inspect the equipment before discharging and working on it.

High Voltage Safety

Wear The Proper Attire: Wear rubber-soled shoes (or simply non-conductive shoes). Use gloves and possibly a facial shield as well. For some power transmission applications, it can also be necessary to use a full-body suit. Wear tight-fitting clothes and tie up your hair to prevent anything from getting caught.
Use Best Practices: Always disconnect the power source before working on the area. Always document and mark high voltage areas. If you are creating high voltage lines or putting parts together, ensure to utilize high voltage stickers or signs so that others will know. Never touch electrical surfaces with damp or wet items. Never touch electrical surfaces with skin. On car batteries, the entire chassis is the ground. As such, ensure to disconnect the ground first (to prevent accidentally placing the positive lead on the car itself), and then the positive. When reconnecting, connect the positive, then the ground.
Always Insulate: Utilize any insulation necessary for exposed wires. When soldering high voltage components, make sure there are no uneven edges or protruding wires from the soldered area. Never touch stripped wires.
Discharge Properly: Discharge the equipment multiple times. Sometimes, there can be some leftover energy throughout the components, and it’s important to do it multiple times to prevent any residual voltage from harming you. Never grip onto a surface without knowing for certain that the equipment is discharged (as if you are electrocuted, you may not be able to release your grip due to involuntary muscle contractions).
Test, test, test: Test as many times as need be. Make sure that you are certain that the equipment is safe to work on, and that everything is properly discharged.

Now, if you or someone you know is being electrocuted, it’s important to remember the following:

The first instinct should be to move away from the source of the electrocution. You should always work with one or more people as you may need to rely on someone to pull you away from the source (as involuntary muscle contractions may not allow you to get away from the area). If you are the one to pull your friend away, ensure that you are insulated and do not come into contact with the source or ground.
Turn off the source, ground the circuit, and call 911. Even if something may not seem wrong, human bodies are very sensitive to electrical shock due to their reliance on electricity for bodily functions, and it is important to make sure emergency help is available should the worse occur. Sometimes, the damages aren’t even visible—severe internal burns can occur, or a heartbeat can become irregular.

It’s always important to consult work manuals, your supervisors, and any other material necessary before embarking on high voltage work. Make sure to take every precaution and to stay safe.