Where the label is
Every appliance sold has one, and it is usually somewhere inconvenient:
- Refrigerator: inside the fridge compartment on a side wall, or on the back near the compressor.
- Freezer: on the back, or inside the lid.
- Furnace: inside the access panel, on the blower housing.
- Air conditioner: on the outdoor condenser unit, on the side facing away from the house.
- Well pump: on the control box or the pressure switch in the basement or well house — not on the pump itself, which is down the shaft.
- Small appliances: underneath, or molded into the plastic near the cord entry.
Take a photograph of each one while you are there. You will want them again, and photographing is faster than writing.
What the fields mean
| Marking | Means | Use it for |
|---|
| W or Watts | Power consumption directly | Running watts — the easiest case |
|---|
| A or Amps, sometimes FLA | Current draw, full load | Multiply by volts to get watts |
|---|
| V or Volts | Supply voltage — 120 or 240 in US homes | The multiplier, and whether a 120V machine can feed it |
|---|
| LRA | Locked rotor amperage — the starting surge, in amps | Multiply by volts for starting watts |
|---|
| RLA | Rated load amps, on compressors | Running current under normal load |
|---|
| HP | Horsepower, on motors | Cross-reference against a wattage chart |
|---|
| Hz | Frequency — 60 in the US | Nothing, unless the appliance is imported |
|---|
| kWh/year | Annual energy from a standardized test | Estimating average draw across a day |
|---|
Not every label carries every field. A well pump label typically gives HP and voltage; an air conditioner gives RLA and LRA; a fridge gives amps and often an annual kWh figure. Use what is there.
Amps to watts
The conversion you will use most, because most labels give amps.
Watts = amps × volts
- A fridge marked 6.5 A at 115 V is about 750 W while the compressor runs.
- A well pump marked 9 A at 240 V is about 2,160 W running.
- An air conditioner with LRA 48 A at 240 V has a starting surge in the region of 11,500 W — which is why soft starters exist.
Note the voltage in each case. A 240V appliance draws twice the watts of a 120V one at the same amperage, and it also means a 120V-only generator or power station cannot feed it at all.
The nameplate is a maximum, not an average
This is the interpretation people get wrong, and it cuts both ways.
A nameplate figure is generally the appliance's draw at full load, in the worst case. It is used for wiring and breaker sizing, where you must design for the maximum.
For backup power that makes it:
- Right for sizing the inverter or generator. You need to cover the maximum, so use the nameplate.
- Wrong for estimating watt-hours. An appliance that cycles — a fridge, a furnace, an air conditioner — averages far below its nameplate across a day.
Which is the same distinction as starting versus running watts, applied one level up: use the maximum for what can start, and the average for how long it lasts.
What the label will not tell you
- Starting surge, unless it happens to give LRA. Most motor appliances do not, which is why manufacturer wattage charts exist.
- Duty cycle. Nothing on any label tells you what fraction of the time it runs.
- Real condition. A twenty-year-old motor with worn bearings draws more than its label. Labels describe new appliances.
- Standby draw. Anything with a clock, a display or a remote receiver draws a little continuously, and none of them say so.
Three ways to get a real number instead
- A plug-in energy meter. A cheap device between the socket and the appliance that reads instantaneous watts and accumulated kilowatt-hours. Leave one on a fridge for 24 hours and you have your actual duty cycle rather than a planning average.
- Your power station's display. Plug the appliance into it and read the output. Free if you already own one, and it shows the surge as well as the running draw.
- A transfer switch with watt meters. Reads whole circuits during a real outage, including the hardwired loads a plug-in meter cannot reach.
Any of the three beats every chart, because a chart is somebody else's appliance in somebody else's house.
Building your own list
Worth half an hour once, and it makes every other sizing decision on this site straightforward.
- Walk the house and photograph every nameplate on anything you would want running in an outage.
- Convert each to watts using amps × volts.
- Note the voltage — 240V items rule out 120V-only equipment entirely.
- Note which are hardwired, because those need a transfer switch rather than a cord.
- Find the largest single starting figure, from LRA where given or from a published chart otherwise.
- Estimate duty cycle for the cycling loads, or measure it.
That list feeds directly into generator sizing and battery sizing, and it is the difference between buying against your house and buying against an article.
