## How to check your electricity usage

**Understanding how to use your meter to monitor your household electricity use can be extremely beneficial, especially if you receive a bill that is higher than expected, or if you think you may have a faulty appliance or meter.**

**You can also measure the consumption of specific appliances and calculate how much the appliance costs to run, or identify if it is using more power than it should. This will help you to control your usage so you will not be shocked by your next bill.**

## How to measure your electrical usage

You can perform a simple test to determine how much power you use at your property.

The number of kilowatt-hours of electricity used per day to run your house before any additional appliances are used is often referred to as the base electricity consumption.

**To measure your base electricity consumption:**

- Turn off all electrical appliances except for anything essential.
- Take a meter read and note the time that the read was taken.
- Do not use anything but essential appliances in the next 24 hours.
- Take a meter read at the same time the next day.
- Subtract the previous read from the current read and you are left with the number of kWhs you use as a base on any given day.

**To measure your electricity use on an average day:**

- Take a meter read and note the time that the read was taken.
- Use your electrical appliances as you normally would on an average day.
- Take a meter read at the same time the next day.
- Subtract the previous read from the current read and you are left with the number of kWhs used per day on an average day.

The test allows you to see the difference between your electricity usage on an average day and your base electricity consumption. If there is a big difference, you may want to reduce your use of additional electrical appliances.

We recommend regular measuring of your daily consumption to monitor whether you have successfully reduced your consumption after a high bill.

## How to measure the usage of an appliance

Locate the input power of the appliance. It is often listed on the appliance itself or on its tags or manuals.

**If the listing is in watts**– divide the watts by 1000 to give you the kilowatts.**If the listing is in amps and volts**– multiply the amps by the volts to get the watts, and then divide the watts by 1000 to get the kilowatts.

**Mechanical Electricity Meters**

- Turn off all appliances, lights, etc.
- Turn on the appliance being measured.
- On the rotating disc, there is a black mark to assist with counting the revolutions.
- Count the number of revolutions the disc makes in one minute while the appliance is running.
- Multiply that number by 60 (to calculate revolutions per hour).
- On the information plate there is a number labelled as “RPK” or “Revs per kWh”. Divide the number of revolutions per hour by the RPK.

The result is the kilowatt rating of the appliance.

For example, when you count 10 revolutions per minute and the RPK is 400, you would calculate the rating as follows:

- 10 x 60 = 600 revolutions.
- 600 ÷ 400 = 1.5 kilowatts.

The appliance is therefore rated at 1.5 kW, and if used for one hour, the appliance would use 1.5 kilowatt-hours (kWh).

**Electronic Electricity Meters**

- Turn off all appliances, lights, etc.
- Turn on the appliance being measured.
- On the face of the meter, there will be a pulsating signal - either a small light or an indicator on the display screen. Each pulse registers one watt-hour.
- Count the number of pulses in one minute while the appliance is running.
- Multiply the number by 60 (to calculate pulses for every hour).
- Divide the number by 1000 (to convert the watts to kilowatts).

The result is the kilowatt rating of the appliance.

For example, where you count 25 pulses per minute you would calculate the rating as follows:

- 25 x 60 = 1500 watt-hours.
- 1500 ÷ 1000 = 1.5 kilowatts.

The appliance is therefore rated at 1.5 kW and if used for one hour, the appliance would use 1.5 kilowatt-hours (kWh).

## What is the cost to run an appliance?

Check your electricity bill to see how much you pay per unit for your electricity (if you do not have your bill, 32c per kWh is an average price) and take your previous calculation of kilowatt-hours.

**Multiply the kilowatt-hours by the unit price and you will have the running cost per hour for your appliance.**

- 1.5 kWh x 32c = 48c per hour.

**If you run the appliance for 5 hours a day, it would cost approximately $2.40 per day to run.**

- 48c x 5 hours = $2.40 per day.

**If you run the appliance for 5 hours every day for the duration of your billing period, then that one appliance alone would cost you approximately $216 for a quarter.**

- $2.40 x 90 days = $16.

You can see how quickly the costs of using certain appliances can add up.

If the appliance was a heater being used during a cold period, even using it every second day for 5 hours (or every day for 2.5 hours) would still add approximately $108 to your bill.

We recommend you compare your bill to the same period last year for a realistic comparison.

## Links and further information

- Energy and Water Ombudsman SA: Understanding your electricity meter.
- Energy and Water Ombudsman SA: Understanding a high electricity bill.
- Energy and Water Ombudsman SA - Fact sheet: Measure electrical usage.
- SA Government: Appliance running costs.