Section 5.2: Hazardous Voltages #

Note: While this section doesn’t contain material directly tied to specific exam questions, the safety information presented here is essential knowledge for any ham radio operator working with electrical equipment.

What Are Hazardous Voltages? #

In the ham radio world, we generally consider anything above 30 volts to be potentially hazardous. That might seem low, but remember, it doesn’t take much to give you a nasty shock or worse.

Where Might You Encounter Hazardous Voltages? #

You might be surprised where hazardous voltages can pop up:

• Test Leads: Whenever you are measuring hazardous voltages don’t forget that the probes you use to measure are then also subject to those dangerous voltages! It’s an easy thing to overlook when testing.

• Power Supplies: That 13.8V power supply for your radio? Inside, it’s converting 120V AC to DC. One wrong move and you could be in for a shock.

• Antenna Systems: Ever heard of “hot” antennas? Some antennas can develop high voltages at their feed points, especially when transmitting.

• Older Equipment: If you’re lucky enough to play with some vintage gear, be extra cautious. Old tube equipment can have voltages in the hundreds or even thousands of volts!

• Capacitors: These little storage tanks can hold a charge long after equipment is unplugged. They’re like electrical grudge-holders.

This is worth emphasizing; when capacitors are involved, just because it’s unplugged and power is off does not mean it’s safe! Many people have hurt themselves by opening equipment and touching the wrong thing before the capacitors were fully discharged.

Staying Safe Around Hazardous Voltages #

So, how do we stay safe?

• Assume Everything is “Hot”: Always assume equipment is live until proven otherwise. Use a voltmeter to check before you touch.

• One Hand Rule: Use one hand when working around high voltages. It sounds weird, but it keeps current from flowing across your chest if you do get shocked.

• Discharge Capacitors Properly: Capacitors can hold a dangerous charge. Learn safe ways to discharge them before poking around—usually through a resistor of appropriate value, never by shorting them directly.

• Use Properly Insulated Tools: When working with potentially hazardous voltages, use tools with insulated handles rated for the voltage you’re working with. Look for tools marked with voltage ratings (often 1000V) and make sure the insulation isn’t cracked or damaged.

• Keep Your Workspace Dry: Water and electricity don’t mix. Make sure your work area is dry and you’re not standing on a damp floor or concrete (which can be conductive).

• Look for Warning Labels: Pay attention to any warning labels on equipment indicating hazardous voltages. If you’re building or modifying equipment, consider adding your own warning labels where appropriate.

• Never Work Alone: When working on high-voltage equipment, always have a buddy around who knows CPR, just in case.

• If You’re Not Sure, Don’t Touch It: There’s no shame in asking for help or leaving it to the experts.

First Aid for Electrical Shock #

If someone does receive an electrical shock:

1. Don’t touch them if they’re still in contact with the electrical source
2. Cut power if possible before providing assistance
3. Call for emergency medical help immediately
4. Provide CPR if the person is unresponsive and not breathing normally
5. Treat any burns after addressing life-threatening conditions

Remember, the goal is to make contacts, not become one with your equipment. Electricity doesn’t care how experienced you are or how careful you think you’re being. It’ll take any path to ground, including through you if you give it the chance.

Stay safe, stay insulated, and may all your connections remain social and not electrical.