What is Voltage?
We view voltage as the end-all measurement of energy in a system. We rank high-voltage lines, substations and any relatively dangerous system using measurements of low and high voltage. These measurements are not always exact – low voltage is usually considered to be roughly 120V AC or lower while high voltage is anything over that ““ and are somewhat misleading since it is the amount of current in a system that is dangerous. So what is voltage?
Voltage in a Circuit
The short answer is that voltage is the difference in electrical potential across a circuit. Water in a pipe is often the easiest way to describe how this works. A switch in a circuit acts like a valve in plumbing. By closing the valve and blocking off the flow of water, you store the potential flow of the water on one side. Voltage acts the same way in that, when a switch leaves a circuit disconnected, there is a difference of potential voltage across the gap.
Every element of a circuit requires a certain amount of electrical potential to function. Power requires both the presence of electricity and the flow (current) of electricity to function. In a series circuit (where all loads are placed one after the other) they share the same current (or flow rate of electrons) over the path of the circuit. In a series circuit, voltage has to be dropped off at each load (whether that load is a light bulb, air conditioner, or refrigerator) which means there’s less for the overall system.  These voltage drops act as a resistance to electron flow in the circuit. When you measure 5 volts across a component or appliance, that’s how much voltage is being used within the system. When a high resistance such as an open switch is added, all voltage is left as potential on one side, stopping flow in the circuit.
Power and Voltage
So if voltage is the potential of electricity in a circuit, why are circuit breakers measured in Amps (for current flow) rather than Volts (for electrical potential)? Your home is designed to split up the circuits and keep 120 volts flowing in parallel (side-by-side) to every outlet. This means that different amounts of current are necessary to deliver the same potential across your outlets. Your breaker is the beginning of this branching point. It monitors the amount of current being delivered into your home’s system to help mitigate power.
You see, as you add more devices, more power is required within a single circuit. Since the voltage is kept constant, the current flow in the circuit has to increase to account for the added resistance. This increased current flow heats up the wiring in your home by a certain amount. Breaker boxes measure this heat mechanically and are forced to trip when the temperature increases past a certain point. Because this tripping point is triggered by a certain amount of current flow, they are rated in Amps rather than Volts or Watts.
The next time your breaker trips, try this: Look at all the devices plugged into the outlets on that circuit. Calculate the total wattage from everything (each light bulb, fan, or portable heater), and divide this total by 120 to get the current being used by the system. If you’re pulling over 20 Amps, (and you can compare this with the breaker rating in your breaker box) then you’re going to trip the breaker.
Hickerson Electrical is your source for all home electrical services.  We’re ready and willing to deliver top-quality service to your home at a moment’s notice. So call today at (703) 594-3913.
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