Crunching the Numbers
2. What Appliances are Demanding Power?
Alright, let’s put on our math hats (don’t worry, it’s not as scary as it sounds). You’ll need to figure out the amperage draw of your major appliances. Most appliances have a label that lists their wattage. To convert watts to amps, you can use a simple formula: Amps = Watts / Volts. In most homes, the voltage is 120 volts for smaller appliances and 240 volts for larger ones like stoves and dryers.
Now, a word of caution: you don’t want to assume that all your appliances are running at their maximum wattage all the time. A refrigerator, for example, cycles on and off. But it’s always best to overestimate slightly to be safe. Add up the amperage draw of all your major appliances — stove, water heater, refrigerator, washer, dryer, microwave, etc. — to get a rough estimate of your current electrical load.
Let’s say you total up all the amperage from your devices and appliances and it comes to 70 amps. With a 100 amp service, that only leaves you with 30 amps remaining for an air conditioner to use. At this point, it is always best to consult a certified electrician before making any changes to your home’s electrical wiring.
Remember to account for peak usage. What appliances are likely to be running simultaneously? For example, are you likely to be running the microwave while the AC is blasting and the dryer is tumbling? Factoring in these scenarios will provide a more accurate picture of your electrical demand, and whether your 100 amp service can realistically handle an AC unit without constantly tripping breakers.