Electrical Measurements Explained

What does 24 Volts, @ 15 amps mean? What is a watt? What’s a watt-hour? What about an amp-hour? These are all crucial ways of measuring how much electricity is present, at what rates, and just how much that electricity wants to move. We are going to be greatly simplifying these concepts, so as always, consult an electrician before working on or making any electrically involved decisions.

Volts and Amps

We’re going to start with the basics: What’s in the wire. The wires around you contain electrons. The movement of these electrons is electricity. When there is electricity, such as a light switch being turned on, electrons are moving through  the wire, creating magnetic fields and heat, among other things. Volts are the amount of force pushing those electrons. A low voltage source such as a double A battery has just enough force inside it to make electrons move through a wire. It doesn’t quite have enough force to shoot electrons into the air and make lightning like an industrial transformer could. The flow of these electrons is called Current, which we measure in Amps (amperes). It’s easiest to picture the current as a flow-rate, “one gallon per hour.”

We can measure the total amount of amps with an Amp-Hour. For example, if we have a pump that needs 10 Amps to run, and it runs for One Hour, that it runs at 10 Amp-Hours. In 24 hours, it will have used 240 Amp-Hours of electricity. There is a catch: if you’re working with batteries, their Amp-Hours are weird. We’re not covering that today, but if you’re going to run a pump off a battery, you will need a lot of extra math to make it work. These amp-hours though aren’t the “volume” of electricity, they’re just the combined current, you don’t know how big the “pipe” is until you add in Volts, which will get you the actual total amount of power.

Volts x Amps = Watts

The Amp-Hour measurement is a little weird. It’s a measure of how much current is used in an hour, and can tell you how many electrons have moved but it’s not exactly a direct “I used a gallon of gas getting to the store” type of measurement. For these we have the measurement of Power, Watts. A Watt is the actual mount of power used in an hour.

If I have a pump that runs at 120 Volts @ 15 Amps, then it’ll use 1800 Watts. If that runs for two hours, it’ll have used 3600 Watt-Hours. If this is sounding similar to the amp-hours, it is, but they are different. One is a flow rate, like a river flowing at 1000 gallons/hour into a lake, while a watt is essentially that actual 1000 gallons.

That is the simplest terms of it. If we go into more detail, there are further units and relations such as Joules, Ohms, and farads. Just for a farad, a farad is the measurement of the ability to store charge (capacitance), a single farad is a coulomb (6.25 billion electrons) @ 1 volt. This is a deep rapid hole of terms and equations.

Can We Make This Useful

(For the rest of us?)



What you need to know when buying new parts or planning an expansion for your facility is that you can:

Push power with enough force to get things done (VOLTS).
That you can supply enough current (AMPS) to do the work.
That you can pay for that amount of power (Watts).

The numbers just have to line up. Your electrician can work some voodoo (can we call it anything else) on site to adapt what your Electrical Providers offer to get the job done or arrange for additional electrical services to get the job done.

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