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How to use an electricity usage monitor

Updated: October 2026

The cost on the screen says a few pence for a heater that has been on all evening, or it says hundreds of pounds for a lamp. Before you blame the meter, check the unit you typed. This is how to use an electricity usage monitor that sits in a UK socket: read kilowatt-hours as the measurement, treat the cost as kilowatt-hours times a rate, and unplug anything that smells hot. Clamp fitting stays on the [plug or clamp page](/hub/measuring-equipment/energy-meter/sub/energy-meter-plug-or-clamp). The twelve listings are in our [energy meter comparison](/hub/measuring-equipment/energy-meter).

The cost on the screen says a few pence for a heater that has been on all evening, or it says hundreds of pounds for a lamp. Before you blame the meter, check the unit you typed.

Our top picks

Tapsin Tapsin energy monitor plug

Best overall

Tapsin Tapsin energy monitor plug
9.0/10about £13.99
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Awootsv Awootsv PM04UK-1 power meter plug

Preis-Tipp

Awootsv Awootsv PM04UK-1 power meter plug
9.0/10about £11.99
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KETOTEK KETOTEK KTEM02UK power meter plug

Alternative

KETOTEK KETOTEK KTEM02UK power meter plug
8.6/10about £18.99
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On this page
  1. 1.What the screen is doing
  2. 2.Enter the tariff in pence
  3. 3.Run one appliance and reset
  4. 4.Stop using it

What the screen is doing

Watts are what the appliance is drawing now. Kilowatt-hours are the energy since you last reset. Cost is kilowatt-hours times the stored unit price. If the price is wrong, the cost is wrong and the kilowatt-hours can still be right. A 10 W LED for an hour uses about 0.01 kWh. Bearware uses Cost and Set. Tapsin uses COST, UP, DOWN and RESET. Use the names on your own meter. Tapsin's backlight lasts about five seconds. Awootsv has none. A dark reading is not a zero reading.

Enter the tariff in pence

Type the unit rate from your bill in pence per kWh, unless the screen clearly asks for pounds. A Bearware review says the instructions should say pence, not pounds. Ofgem's example for England, Scotland and Wales this quarter is 26.32p per kWh. It is not your price and not Northern Ireland. A 1000 W heater for six minutes should add about 0.1 kWh, about 2.6p at 26.32p. If the cost moves by £2.60, you entered pounds on a pence meter. Reset and run the six minutes again.
Tapsin Tapsin energy monitor plug

Testsieger

Tapsin Tapsin energy monitor plug
9.0/10about £13.99
View offer

Run one appliance and reset

Reset before the test, then write the kilowatt-hours down. A UK review says the Tapsin cost line rolls back to zero at 99.99. Keep the kilowatt-hour line. Bearware's listing says two LR44 cells keep the settings. A UK review says the kilowatt-hours cleared around midnight. Reset when you move from the kettle to the tumble dryer, or the second appliance inherits the first. A KETOTEK review says the timer paused when a heater thermostat opened. That is run time under load, not the clock.

Stop using it

Unplug the meter if the body is hot, if you smell plastic, or if the breaker opens. The Health and Safety Executive says you stop using equipment that appears faulty. One Bearware review describes a near fire. Do not open the consumer unit. When the kilowatt-hours look trustworthy, use how to calculate appliance running cost and your own unit rate. If you have not chosen a plug, a clamp or a DIN rail, the buying guide is the fork. A qualifying purchase can earn a commission at no extra cost to you.

Common questions

Do I enter 26.32 or 0.2632?
Enter 26.32 if the meter expects pence per kWh, which is the usual socket-meter habit in this set, and only if 26.32p is actually your rate. The figure is Ofgem's Direct Debit example for England, Scotland and Wales from 1 October to 31 December 2026, not a personal tariff and not Northern Ireland. If a six-minute test on a known load makes the cost a hundred times too big or too small, the unit is wrong. Correct it and repeat the test.
Which button sets the price?
It depends on the brand. Bearware's listing says Cost and Set. Tapsin uses a COST button with UP, DOWN and RESET. KETOTEK listings say the tariff is stored, without a shared button map. Read the card that came with your meter, then prove the rate with a short timed load. Do not borrow a COST-hold sequence from a different brand's PDF and assume the screen agreed.
Why did the cost go back to zero at 99.99?
On the Tapsin, a UK review says the cost display reaches 99.99 and rolls back to zero. The kilowatt-hour memory is a separate reading. Photograph or write down the kilowatt-hours before a long run, and do not treat a zero cost as proof the appliance used nothing. If you need a larger money total, multiply the kilowatt-hours by your unit rate on paper.
Why is this morning's kilowatt-hour reading gone?
Bearware's listing says two LR44 cells keep the settings when you unplug it. A UK review says the kilowatt-hour display cleared around midnight. Both statements are in the sources, and they disagree. If your meter has done that once, do not trust it with an unattended week. Note the reading before you go to bed, or move the test to a meter whose memory you have watched survive a night.
Do I reset before every new appliance?
Yes, if you want that appliance alone. Leave the old kilowatt-hours in place and the next cost includes the previous load. You do not need to reset every time you glance at the same fridge. Reset when you change what is plugged in, and write the result down before you move the meter again.
The plug got hot. What now?
Switch the appliance off, unplug the meter from the wall, and do not plug it back in to see if it still works. Heat, a burning smell, or a breaker that opened are reasons to stop, which matches the HSE advice on faulty equipment. One Bearware UK review describes a near fire. Let a competent person look at the socket if the wall plate is warm or marked. Do not open the consumer unit yourself.

Related pages

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Electricity usage monitor buying guide for UK homes

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How to calculate appliance running cost in a UK home

Sources

Public UK sources on the price cap, trade meters, notifiable electrical work and competence. Shelf prices, stars and review counts are the amazon.co.uk lines in the twelve listings dated 16 October 2026. Prices move.

  1. Ofgem, energy price cap 1 October to 31 December 2026 (retrieved 16 October 2026)
  2. Ofgem, energy price cap unit rates and standing charges (retrieved 16 October 2026)
  3. GOV.UK, Measuring Instruments Regulations 2016, Great Britain (retrieved 16 October 2026)
  4. Measuring Instruments Regulations 2016, SI 2016/1153 (retrieved 16 October 2026)
  5. GOV.UK, building work, replacements and repairs (retrieved 16 October 2026)
  6. HSE, electrical safety introduction (retrieved 16 October 2026)
  7. Electricity at Work Regulations 1989, regulation 16 (retrieved 16 October 2026)
  8. Which?, energy monitors and measuring power use (retrieved 16 October 2026)