Splitting the electricity bill between tenants, separating a home's consumption from a shop's, or justifying a building's shared costs: all of that is usually done by eye, with estimates that end in arguments.
The Shelly Pro EM-50 solves the problem with two independent measurement channels: you can measure two circuits separately with a single unit, and with exportable data.
One unit, two separate consumptions
The unit has two clamp inputs, IA and IB, and each handles up to 50 A. Each clamp goes around a different circuit and the meter records both separately, with 1% accuracy.
The most common uses we see:
- A home rented by rooms or split in two. Each zone on one channel, and the split stops being an estimate.
- A shop on the ground floor of a home. Separating the business consumption from the private one, especially useful for tax deductions.
- Isolating a specific load. A pool pump, an industrial oven or an HVAC unit, to know what it really costs to run.
- Shared costs in buildings. Lift, garage or common-area lighting, measured with data rather than split by coefficient.
Why the data holds up in an argument
What makes the Pro EM-50 a valid tool for splitting costs isn't just that it measures, but how it stores what it measures.
It stores at least 60 days of history at one-minute resolution in non-volatile memory, and exports to CSV and JSON. You can pull the exact consumption for a specific period and attach it to a settlement.
It also has a real-time clock, so timestamps stay correct even if the internet goes down for days.
An important caveat: it's not a certified billing meter. It's for splitting internal costs fairly and with documentation, but it has no legal validity as an official meter against an electricity retailer.
From data to action
The second advantage of the Pro EM-50 over the three-phase models is that it has a built-in relay, so it doesn't just watch: it can act.
With the Gen2 firmware you can write scripts and automations on the device itself: cut a load if a threshold is exceeded, activate a circuit during off-peak hours or alert when a tenant goes over the agreed consumption.
The output is terminals I and O, a galvanically isolated dry contact of up to 2 A at 240 V.
Safety warning: those 2 A are for driving the coil of a contactor, never for powering the load directly. A water heater, a pump or an oven needs an intermediate contactor rated for its power. Connecting them directly destroys the unit, and it's the most expensive mistake made with this model.
What you need to install it
- A Shelly Pro EM-50 and room for one module on the DIN rail.
- Two 50 A clamps, one per circuit to measure.
- If you're going to cut loads, a contactor rated for the actual power.
We detail the step-by-step installation in the Pro EM-50 installation guide.
Is it the model you need?
The Pro EM-50 is single-phase and goes up to 50 A per channel. If your supply is three-phase or you need to measure a large service, look at the Pro 3EM. We compare everything in the guide to choosing a Shelly energy meter.
Got a specific cost-splitting case? Tell us about it and we'll say whether the Pro EM-50 covers it. Technical support in English and shipping from Spain.
