CT101 vs WS523: current clamp or smart socket for energy monitoring?
Short answer: They measure in different places. The CT101 clamps round a conductor inside a distribution board and reports RMS current on circuits up to 100 A, powering itself from that current. The WS523 plugs into a wall socket between the socket and one appliance, measures voltage, current, power factor, active power and energy, and can switch the appliance on and off. Hardwired circuits point to the CT101; single plug-in loads point to the WS523.
What are you measuring?
Choose the CT101 for circuits: lighting, air conditioning, a kitchen, a machine that is wired in. It fits a conductor through a 16 mm opening, and fitting it inside the board is work for a competent electrician.
Choose the WS523 for one plug-in appliance, such as a vending machine, a fridge, a printer or a heater. It needs no wiring: it plugs into an existing socket, and Milesight lists a UK Type G version rated at 13 A.
Accuracy and what is measured
The CT101 measures current only, to ±1% above 5 A and ±3% at 5 A and below, so energy is calculated with an assumed voltage and power factor. The WS523 measures voltage and power factor as well, and reports active power and energy, to typically ±3% and at most ±5%.
Control and alerts
The WS523 switches its load by its button or remotely, with a delay switch, button lock, overcurrent protection and alarm, and a power outage alert from a built-in capacitor. It runs LoRaWAN Class C, so it listens for commands continuously. The CT101 only measures, and when self-powered it needs about 1.5 A at a 1 minute interval to keep reporting, or a 5 V USB-C supply.
Environment
The WS523 is IP20 and rated from -20°C to 60°C. The CT101 is IP30 and rated from -20°C to 70°C. Both are for indoor use.
Milesight CT101 / CT103 / CT105 Smart Current Transformer – CT101
CT101-868M
£62.85 ex VAT (£75.42 inc. VAT)
View the CT101-868M
Milesight WS523 Smart Portable Socket
WS523-868M
£62.85 ex VAT (£75.42 inc. VAT)
Socket Type & Rated CurrentOrdered per region — UK-13A (PN 13A-UK, Type G, max current 13 A); also EU-16A, FR-16A, US-15A, AU-10A, CN-10A and CN-16A
View the WS523-868MSpecification comparison
| Specification | CT101-868M | WS523-868M |
|---|---|---|
| Advanced Features | — | Delay Switch, Button Lock, Overcurrent Protection/Alarm, Multicast, Power Outage Alert, Milesight D2D Agent |
| Antenna | — | Internal Antenna; line-of-sight transmission up to 15 km |
| Configuration | — | Mobile App via NFC or Downlink; NFC card emulation mode supported |
| Dimensions / Weight | — | 110 × 62.3 × 34.6 mm (4.33 × 2.45 × 1.36 in, plug not included); 117.5 g |
| Frequency | — | CN470/IN865/RU864/EU868/US915/AU915/KR920/AS923-1&2&3&4 |
| Ingress Protection | — | IP20 |
| LED Indicator | — | 1 × Network/Power Status LED Indicator |
| Material & Color | — | Polycarbonate (UL94 V0), White |
| Measurement | — | Voltage (VAC), Current (mA), Power Factor (%), Active Power (W), Power Consumption (kWh) |
| Measurement Accuracy | — | Typical ±3%, Maximum ±5% (±1% customizable) |
| Mode | — | OTAA/ABP Class C |
| Operating Temperature | — | -20°C to +60°C (-4°F to +140°F) |
| Operating Voltage | — | 100~250 VAC, 50~60 Hz |
| Power Control | — | Local Press Button or Remote Control |
| Power Outage Alert | — | Equipped with capacitor for power outage alert |
| Regulatory | — | CE, FCC, RCM, SAA, UKCA; RoHS |
| Relative Humidity | — | 10% to 90% (non-condensing) |
| Socket Type & Rated Current | — | US-15A/EU-16A/AU-10A/UK-13A/CN-10A/CN-16A/FR-16A, etc. |
| Tx Power / Sensitivity | — | 16 dBm (868 MHz) / -137dBm |
| Wireless Transmission Technology | — | LoRaWAN, Milesight D2D |
Specifications taken from the manufacturer datasheets. Rows where the models are identical are dimmed. Prices are ex VAT and read live from the catalogue.
Frequently asked questions
Can a CT101 switch a circuit off?
No. The CT101 only measures current. The WS523 can switch the plug-in appliance connected to it.
Does the WS523 need an electrician?
No. It plugs into an existing wall socket and the appliance plugs into it. The CT101 goes inside a distribution board, which is a job for a competent electrician.
Which is more accurate?
The CT101 measures current to u00b11% above 5 A. The WS523 measures power and energy to typically u00b13% and at most u00b15%, with u00b11% available as a customisation.
Can the WS523 report a power cut?
Yes. It has a built-in capacitor for a power outage alert.