Pulse Counter: Reading the Gas and Electricity Meters You Already Own

TL;DR: Many gas and electricity meters already emit a pulse for every fixed quantity of energy or gas they measure. A pulse counter counts those pulses and sends them to a dashboard, so an existing meter becomes a live data source without being replaced. The value of each pulse is printed on the meter, and gas pulses become kilowatt hours through a formula set in UK regulations. Get the pulse value or the wiring wrong and the data is confidently wrong.

Last updated: 14 September 2026

Key takeaways

• A pulse counter counts the pulses a meter emits, each representing a fixed quantity, and multiplies by that quantity to give consumption over time.
• Gas bills in the UK are calculated from volume using the Gas (Calculation of Thermal Energy) Regulations 1996: volume, times calorific value, times 1.02264, divided by 3.6.
• Government guidance says gas transporters keep the calorific value between 38 and 41 MJ per cubic metre, so the conversion is stable enough for management data.
• Electricity meters with an S0 output follow EN 62053-31, a passive, two wire, externally powered pulse interface. Check compatibility before you connect.
• The most common failure is not hardware. It is a wrong pulse value entered at set up, which scales every reading by the same error.

What is a pulse counter?

A pulse counter is a small device that counts the electrical pulses a utility meter produces and reports the running total. Each pulse stands for a fixed quantity, such as a hundredth of a cubic metre of gas or one watt hour of electricity, so counting pulses over time gives consumption over time. The meter keeps doing the measuring. The counter makes its readings available remotely.

That is the whole appeal. Many commercial sites have gas and electricity meters that measure perfectly well but are read by eye, once a month or once a quarter, or not at all below the main incomer. A pulse counter turns those meters into interval data for a few tens of pounds per meter, which is why it is often the first step in any energy monitoring plan.

The Milesight EM300-DI is a LoRaWAN pulse counter with one dry contact input that can count at up to 2,000 Hz, with a minimum pulse width of 250 microseconds. It is listed at £47.88, runs for around five years on its battery at a ten minute reporting interval, and also measures the temperature and humidity where it is fitted.

Which meters have a pulse output?

Many do, but not all, and the type matters. Gas meters commonly provide a reed switch output, a magnet in the index that closes a switch once per fixed volume, or a pulse ready index designed to take a clip-on pulse unit. Electricity meters commonly provide an S0 output, which the standard behind it, EN 62053-31, describes as a passive, two wire, externally powered pulse output device that transmits pulses representing a finite quantity of energy.

The pulse value is printed on the meter or its data plate. On a gas meter it is a volume per pulse. On an electricity meter it is usually shown as impulses per kilowatt hour. That number is the single most important fact in the whole installation, because the pulse counter cannot know it and will multiply by whatever it is told.

Before buying, record three things for each meter: the pulse value, the output type, and whether the output is already used by something else, such as a building management system. Remember too that the meter often belongs to the supplier or its meter operator rather than to you, so use the output it provides and do not modify the meter itself.

How do you turn gas pulses into kWh?

Multiply the volume by the calorific value, multiply by 1.02264, then divide by 3.6. Government guidance on gas meter readings and bill calculation explains that these steps are prescribed in the Gas (Calculation of Thermal Energy) Regulations 1996. The 1.02264 factor corrects the volume for temperature and pressure, and dividing by 3.6 converts megajoules to kilowatt hours.

Here is a worked example for a hypothetical gas meter that emits one pulse per 0.01 cubic metres, using the illustrative calorific value of 39.5 MJ per cubic metre quoted in the same guidance:

The calorific value changes slightly with the gas supplied, and your bill shows the figure used. The guidance notes that gas transporters are required to keep it within 38 to 41 MJ per cubic metre, so a pulse counter using a sensible fixed value will track the bill closely enough for energy management, even though it is not the billing record. Imperial meters read in hundreds of cubic feet, and the guidance gives 2.83 cubic metres per hundred cubic feet for the conversion.

What are the three mistakes that make pulse data wrong?

Almost every bad pulse installation fails in one of three ways, and none of them is the radio. Each produces data that looks plausible, which is what makes them expensive: a counter that reports confidently wrong numbers can drive a year of wrong decisions before anyone checks it against the bill.

1. The wrong pulse value. Enter 0.1 instead of 0.01 cubic metres per pulse and every reading is ten times too high, forever. Always check the first month of pulse counter data against the meter register and the bill.
2. The wrong output type. A reed switch is a simple contact. An S0 output is externally powered, so it needs the right supply and polarity. A pulse counter with a dry contact input, like the EM300-DI, reads reed switches and passive volt free contacts directly, so confirm an S0 meter is compatible before ordering.
3. Lost history at a meter change. When a supplier replaces a meter, the pulse value and the register both change. Log the swap, the final reading and the new pulse value on the day, or the data series will jump.

Where does a pulse counter fit, and where does it not?

A pulse counter is the right tool when a meter already has a pulse output and you want interval data without replacing anything. It is the wrong tool where there is no output to count, and it is never a replacement for the supplier’s billing meter, which remains the legal record of what you pay for.

Where a circuit has no meter at all, clamp-on current transformers measure electricity directly. Our guide to LoRaWAN current transformers covers sizing them. Where the building needs a full picture, our guide to IoT energy monitoring shows how pulse counters, CT clamps and temperature sensors fit together.

Like any LoRaWAN sensor, the EM300-DI needs a gateway, and one gateway will usually serve every meter room in a building. Pulse data on gas and electricity is also exactly what an energy audit asks for: our ESOS Phase 4 guide explains why metered data beats estimates when the assessor arrives.

Frequently asked questions

What does a pulse counter do?

A pulse counter counts the pulses a meter produces, each representing a fixed quantity of gas, electricity or energy, and reports the total at regular intervals. It turns an existing meter into a source of remote interval data without replacing it.

How do I find the pulse value of my meter?

It is printed on the meter or its data plate: a volume per pulse on gas meters, and usually impulses per kilowatt hour on electricity meters. If it is not visible, ask the meter operator before configuring the counter.

How do I convert gas pulses to kWh?

Multiply the pulses by the pulse value to get cubic metres, multiply by the calorific value from your bill, multiply by 1.02264 and divide by 3.6. The method is set out in the Gas (Calculation of Thermal Energy) Regulations 1996.

Can a pulse counter read an S0 electricity meter?

It depends on the counter. S0 outputs are passive, two wire, externally powered pulse outputs under EN 62053-31, so the counter must supply and read them correctly. Check compatibility and polarity before connecting.

Can pulse counter data be used for billing?

No. The supplier’s meter reading is the billing record. Pulse counter data is management information, ideal for spotting waste, profiling demand and preparing an energy audit.

Where to start

Walk the plant rooms with a phone camera and photograph every meter’s data plate. You will know within an hour which meters have pulse outputs, what their pulse values are, and which circuits need CT clamps instead.

Then fit a pulse counter to the biggest gas meter first, check its first month against the bill, and expand from there. The Kit Builder will put the counters, sensors and a LoRaWAN gateway together at listed prices.

By GP, Indiott.