Voltage vs. Amperage
Voltage and amperage do not mean the same thing, though they both are measures of electrical current or flow of electrons. Voltage is a measure of the pressure that allows electrons to flow. Amperage is a measure of the volume of electrons. An electrical current at 1,000 volts is no more deadly than a current at 100 volts. But tiny changes in a current’s amperage can mean the difference between life and death when a person receives an electrical shock. Although the physics are complicated, some experts use an analogy of a flowing river to explain the principles of electricity. In this analogy, voltage is the steepness, or pitch, of the river, while amperage is the volume of water in the river. An electrical current with high voltage but low amperage can be seen as a narrow, small river flowing nearly vertically like a tiny trickle of a waterfall. It would have little potential to hurt you. But a large river with lots of water (amperage) can drown you even if the speed of flow (voltage) is relatively slow. Thus, with amps vs. volts, the danger is in the amps.
Effects of Amperage on Electrical Shock
Different amounts of amperage affect the human body in different ways. The following list explains some of the most common effects of electrical shock at various amperage levels, according to the U.S. Occupational Safety and Health Administration (OSHA). To understand the amounts involved, a milliampere (mA) is one-thousandth of an ampere (or amp). A standard household circuit that supplies your outlets and switches carries 15 or 20 amps (15,000 or 20,000 mA).
1 to 5 mA: Little electrical shock is felt; upsetting but not painful6 to 30 mA: Painful shock; loss of muscle control50 to 150 mA: Extreme pain; possible severe muscle reactions; possible respiratory arrest; possible death1,000 mA to 4,300 mA: Heart ceases pumping; nerve damage; death likely10,000 mA (10 amps): Cardiac arrest; severe burns; death likely
This gives you an idea of just how much danger there is in the home wiring system we take for granted, where wires carry 15,000 or 20,000 mA.
Staying Safe
The best way to prevent electrical shock is to follow standard safety procedures for all electrical work. Here are some of the most important basic safety rules:
Shut off the power: Always turn off the power to a circuit or device that you will be working on. The most reliable way to shut off the power is to switch off the breaker for the circuit in the home’s service panel (breaker box). Test for power: After turning off a circuit’s breaker, check the wiring or devices you will be working on with a non-contact voltage tester to confirm the power is off. This is the only way to be sure you turned off the correct circuit. Use insulated ladders: Never use an aluminum ladder for electrical work. Always use an insulated fiberglass ladder to keep you safe. Stay dry: Avoid wet areas when working around electricity. If you are outdoors in damp or wet conditions, wear rubber boots and gloves to reduce the chance of getting shocked. Plug power tools and appliances into a GFCI (ground-fault circuit interrupter) outlet or GFCI extension cord. Dry your hands before grabbing any cord. Post warnings: If you are working on the service panel or a circuit, place a warning label on the face of the panel to warn others not to turn on any circuits. Before turning the power back on, make sure no one else is in contact with the circuit.
Wattage and Other Electrical Terms
You likely have also heard the term watts when dealing with electricity but might be wondering what they are and how amps vs. volts. vs watts relate. Watts are the rate of power flow. To calculate watts, multiply volts by amps. When considering a 60-watt bulb, that number tells you how much power it takes to run that bulb. Another electrical term you might be familiar with is ohm. Ohms measure resistance in electrical flow. Wiring causes some resistance, or a slowing of the electrical current as it flows on the wires. Appliances and other electrical devices also create some resistance.
