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Your Electric Ireland Business Glossary

Below, you’ll find a Glossary of all the terms used on your business electricity and gas bills.

Volt (V)
A volt is the electrical force required to push current through an electrical circuit.

Most businesses are supplied at a nominal voltage of 400V (three phase), which is frequently referred to as 'Low Voltage'.

Kilovolt (kV) = 1000 volts
This term is normally used for medium and high voltage business customers.

Amp (A)
An amp is the measurement of current flowing in an electrical circuit.

Kilovolt-Amp (kVA) = 1000 volt-amps
This term is used to describe the level of 'apparent' power imported by your business.
It is the basis of your MIC contract with ESB Networks.

Watt (W)
A watt is the unit of measurement of 'active/real' power.

For example, 1 volt passing a current of 1 amp through a basic circuit means your business uses 1 watt of electric power.

Kilowatt (kW) = 1000 watts (W)
A kW is the term used for 'active/real' electric power, it’s also known as 'Demand' or 'Load'.

Electric power is made up of:

  • Active/real power (kW)
  • Reactive/wattless power (kVAr)


When these are combined they are known as the 'apparent' power (kVA).

Megawatt (MW) = 1000 kilowatts (kW)
A megawatt is sometimes used as a unit of measurement for large electric loads provided to business customers.

Kilowatt hour (kWh) = 1000 watts for 1 hour
1 kWh is the amount of energy consumed by an electrical device (e.g. an electric heater) rated at 1kW (1000 watts) for 1 hour.

On your Bill, you will see each 1 kWh used by your business as 1 unit.

Megawatt hour (MWh) = 1000 kilowatt hours (kWh)
MWhs are the measurement of energy used by large industrial businesses.

Wattless unit (kVArh) = 1000 reactive volt-amps per hour
A kVArh is the unit of measurement for 'reactive/wattless' power consumed.

Electric power is made up of…

  • 'active/real' power (kW)
  • 'reactive/wattless' power (kVAr).

Which equals the 'apparent' power (kVA).

Large motors require 'reactive/wattless' power to operate correctly. Your business can reduce/eliminate reactive power by fitting power factor correction equipment. Please discuss with your electrical contractor.

Wattless charges are recorded on a separate meter.

Power factor = 1 or less
This term describes the relationship between kW, kVAr, and kVA.
It is always 1 or less. For example, if your power factor equals 1, then the kW used is equal to the kVA.

If your power factor is less than 1, then you are using some wattless power on your premises. We will only charge you for wattless power when the power factor goes below 0.95.

Load factor
Load factor is the ratio of average electricity used to the peak usage in a business premises during a specific period.

It shows whether the electricity used in your business is stable or has extreme peaks. The lower the load factor the more 'peaky' the loads. A very poor load factor would be less than 20%.

Other Bill Terms and Levies

Maximum Demand (Summer/Winter)
 This annualised charge applies to DG6 price plans only. Your maximum demand charge is divided by the number of days in the year multiplied by the number of days in your billing period.

Capacity charge
 The MIC yearly charge per kVA is divided by 365 and multiplied by the number of days in the billing period.

Carbon Tax
The Government’s 2010 Finance Bill introduced a carbon tax to be applied to mineral oils, natural gas and solid fuels supplied for combustion in Ireland.
From 1st May 2023 the tax for natural gas is €48.50 per tonne of Carbon Dioxide (CO2) emitted. All gas suppliers must apply the carbon tax to customer’s bills.

You will see the carbon tax rate from 1st May 2023, on your bill as 0.877 cent/kWh.

Note: This is subject to change. For further details see http://www.revenue.ie/en/index.html
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