Best CT Clamps for Energy Monitoring: 2025 Expert Review
Oli
Owner, OR Electrics
Energy monitoring has shifted from a niche hobby to a necessity. With energy prices as they are, and the rise of high-load appliances like EV chargers and heat pumps, knowing exactly what your home is drawing from the grid is vital. CT (Current Transformer) clamps are the standard way we measure this safely.
In Leeds, I often find homes with older 60A main fuses. If you add a 7kW EV charger to that without proper load balancing (monitoring via a CT clamp), you risk blowing the main cutout fuse. That is not a simple trip switch you can flick back on; it requires the DNO to come out and dig up the pavement.
In this review, I'm looking at three options available right now: a simple budget replacement sensor, a smart ZigBee-enabled monitoring system, and a compact industrial-grade sensor for tight spaces.
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Specs vs. The Real World
The Spec: "Non-Invasive Installation"
"You can clip the sensor around the cable without disconnecting any wires or interrupting power."
Whilst the sensor clips on (split core), accessing the meter tails often means removing the cover of the consumer unit. This exposes live busbars. This is a job for a competent person or electrician.
The Spec: "100A Measuring Range"
"The device can measure currents up to 100 Amps seamlessly."
Most domestic single-phase supplies in the UK are fused at 60A, 80A, or 100A. If you are consistently hitting the upper limit of these clamps, your main fuse is likely already melting.
My Top 3 Recommendations
Three options to cover different needs and budgets
Ct Clamp Energy Monitor Current PEACEFAIR PZCT-02 Split Core Current Transformer Coil Sensor for 100A Amp Energy Meter
Fauitay
This is a no-frills, split-core CT sensor intended to be paired with a specific energy meter (like the Peacefair range). It is ideal if you have an existing system with a damaged sensor and need a low-cost replacement.
The Good
- Very affordable replacement part
- Small 16mm bore fits standard 16mm² and 25mm² meter tails
- Snap joint structure allows fitting without disconnecting cables
The Bad
- This is just the sensor coil - needs a compatible meter to work
- Short fly leads may need extending for some heavy-duty installations
Installer Tip:
Pay close attention to the arrow on the casing. CT clamps have polarity; if you install it facing the wrong way relative to the current flow (P1 to P2), your energy monitor might read 'export' instead of 'import' or show negative values.
Priced at £7.99 at the time of writing
Check Price on Amazonfor HPLIVE for Energy Monitor with for CT Current Clamp, for Tuya for Smart Life for ZigBee, Intelligent Bi-Dire for CTional Performance Monitor
HpLive
Unlike the budget pick, this is a complete intelligent monitoring solution. It integrates with the Tuya/Smart Life ecosystem via ZigBee, allowing you to visualise voltage, current, and total energy consumption on your phone. Perfect for tech-savvy homeowners wanting granular data.
The Good
- Provides real-time data to your smartphone
- Bi-directional metering is excellent for homes with Solar PV
- Can help identify abnormal consumption patterns
The Bad
- Requires a ZigBee hub (not direct WiFi)
- More complex setup than a basic display meter
Installer Tip:
In Leeds' solid brick terraces, ZigBee signals can struggle to penetrate thick walls if your hub is far away. Ensure your ZigBee hub is reasonably close to the consumer unit or distribution board to maintain a reliable connection for data logging.
Priced at £28.53 at the time of writing
Check Price on AmazonCt Clamp Energy Monitor, Clamp Home Energy Monitor Current Sensors Current Transformer Current Clamp Meter PZCT-02 Split Current Transformer Coil Sensor for 100A Amp Energy Meter
Cosiki
The main selling point here is the compact form factor and robust insulation. In crowded fuse boxes—something I see daily in Headingley and Armley—space is at a premium. This sensor is designed to squeeze into tight gaps between neutral bars and RCBOs without compromising safety.
The Good
- Smallest in class footprint for tight consumer units
- Flame-retardant casing improves fire safety compliance
- Robust build quality compared to cheaper generic sensors
The Bad
- Slightly pricier than the budget option for similar raw functionality
- Still requires a separate meter to read the signal
Installer Tip:
Even though this claims to allow 'Power-On Maintenance', as a safety-conscious electrician, I strongly advise isolating the supply before installing any equipment inside a consumer unit. The clamp is safe, but your hands will be near live busbars.
Priced at £14.57 at the time of writing
Check Price on AmazonFrequently Asked Questions
What does a CT clamp actually do?
Why do I need a CT clamp for my EV charger?
Can I install a CT clamp myself?
Will these clamps work with any energy monitor?
Do these clamps need batteries?
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