Northern Ireland electricity guide
Appliance Running Costs in NI: Work Out the Real kWh
Published on 30 June 2026 by Wee Switch NI Team. Last reviewed 30 June 2026.
A practical way for Northern Ireland households to turn appliance wattage, hours and tariff unit rates into a clearer electricity cost check.
When a bill feels high, it is tempting to blame the supplier first. Sometimes the tariff is the problem, but sometimes one appliance, timer or daily habit is quietly using more kWh than expected. A simple running-cost check helps you separate usage from price before switching.
Monthly Direct Debit or top-up spend can move around because of season, account balance, estimated readings or price changes. kWh is cleaner: it tells you how much electricity was actually used.
For a plug-in appliance, the basic estimate is: watts divided by 1,000, multiplied by hours used. A 2,000 watt heater running for one hour uses about 2 kWh. A 100 watt device running for ten hours uses about 1 kWh.
Some appliances draw the labelled power only at certain times. A kettle draws heavily for a short burst. A fridge-freezer cycles on and off. A washing machine may use most energy when heating water. For anything that cycles, a plug-in energy monitor or the appliance's annual kWh label can be more useful than a single wattage figure.
Always-on appliances deserve attention because small differences repeat all year. Fridge-freezers, network equipment, pumps, dehumidifiers, older entertainment equipment and chargers left permanently on can all be worth checking, especially if usage has risen without an obvious reason.
An appliance running-cost estimate uses the unit rate only. Your standing charge is a daily cost for having the supply available, so it belongs in whole-tariff comparisons rather than in the cost of boiling a kettle or running a tumble dryer.
Pick one appliance or routine at a time. Take a meter reading, change the routine for a normal week, then take another reading. If the week included guests, illness, school holidays or unusual heating use, note that beside the reading so you do not overinterpret the result.
Before switching, work out whether the bill is high because the unit rate is poor, the standing charge is high, or the household is using more kWh than expected. A few appliance checks can make the tariff comparison more accurate and stop one hidden load from confusing the whole decision.
Start with kWh, not monthly spend
Use the simple appliance formula
How this guide is reviewed
This guide is reviewed for Northern Ireland relevance, current supplier status, and tariff-sensitive claims. Tariff figures should be checked against the latest Consumer Council NI source before publication.