rel="sponsored nofollow"), we may earn a small affiliate commission from Amazon UK at no extra cost to you. See our Affiliate Disclosure and BS 1363 Testing Methodology.With British domestic electricity unit rates averaging between 22p and 26p per kWh on standard variable tariffs—and swinging sharply on Time-of-Use tariffs like Octopus Agile—an energy monitoring smart plug pays for itself within weeks if it helps you spot a single vampire appliance. Building on our main best smart plugs UK testing, we compared the leading UK energy-tracking sockets against a calibrated reference inline wattmeter across both low-wattage standby loads (3W–15W) and heavy resistive loads (2,000W+).
At-a-Glance UK Specification & Price Comparison
All models below feature a native UK Type G three-pin plug or socket conforming to BS 1363 (230V–240V AC, 50Hz) and have been evaluated for British double wallplate clearance, standby wattage, and local network reliability:
| Model (UK BS 1363) | Accuracy (>10W) | Tariff Support | Data Retention / Export | UK Price & Link |
|---|---|---|---|---|
| TP-Link Tapo P110M | ±1.8% | Single Rate & Time-of-Use (p/kWh) | Daily / Monthly / Yearly in App | £11.99 (Amazon UK) |
| TP-Link Tapo P110 | ±1.8% | Single Rate & Time-of-Use (p/kWh) | Daily / Monthly / Yearly in App | £8.99 (Amazon UK) |
| Meross MSS315 (UK) | ±2.1% | Single Rate (£/kWh) + Balcony Solar | Historical Graphs + CSV Export | £19.99 (Amazon UK) |
| TP-Link Tapo P304M Strip | ±2.0% per socket | Per-Socket kWh & £ Tracking | 4 Independent Outlets Monitored | £36.99 (Amazon UK) |
1. Why Low-Wattage Power Factor Accuracy Matters in UK Homes
Cheap unbranded smart plugs often use basic current-shunt circuits that fail to account for reactive power (Power Factor) on non-linear switch-mode power supplies—such as Sky Q boxes, gaming PCs, and broadband routers. When we tested a 14W home server load (0.62 power factor), both the Tapo P110M and Eve Energy UK stayed within 0.3W of our reference meter.
Best Single-Socket Value: Tapo P110 & P110M
In the Tapo app’s Energy Monitoring dashboard, you can select GBP (£), choose between Flat Rate and Time-of-Use billing, and view real-time wattage alongside daily and 30-day kWh totals. It also integrates directly into Home Assistant’s Energy Dashboard via the local TP-Link Smart Home integration. Check prices on Amazon UK.
Best for Multi-Plug Media Cabinets: Tapo P304M UK 4-Way Strip
Many smart extension leads only measure total combined power across the entire strip. The UK-spec TP-Link Tapo P304M features independent metering ICs on each of its four BS 1363 sockets, letting you monitor your OLED TV, soundbar, games console, and Apple TV separately from one wall outlet.
How We Test (UK BS 1363 Workbench Protocol)
Our evaluation protocol is specifically designed around British domestic electrical standards rather than generic international spec sheets:
- Twin Wall Socket Clearance (BS 1363-2): We fit each plug into a standard UK MK Logic Plus and BG Nexus double switched wall socket to verify that a casing width of 52–57 mm leaves the adjacent socket and individual rocker switches completely unobstructed.
- True-RMS Standby & Relay Wattage: Using a calibrated 230V/50Hz inline wattmeter (0.1W resolution), we log 24-hour parasitic power consumption both with the relay open (Wi-Fi/Thread listening) and with the relay closed (energised coil + status LED).
- Thermal Pin & Load Verification: While a BS 1363 fuse is rated to 13A (2,990W at 230V), we monitor brass pin temperature after 60 minutes under sustained 2,200W resistive load and verify over-current auto-shutoff behaviour in the companion firmware.
- UK ISP Router & Offline Timer Resilience: We test 2.4 GHz onboarding on merged SSIDs (BT Smart Hub 2, Sky Max Hub, Virgin Media Hub 5) and disconnect the WAN fibre cable to confirm whether scheduled timers and local Matter/Thread automations still execute on time.
Does the Tapo P304M 4-way extension strip report all four sockets individually into Home Assistant as separate kWh entities?
Hi David, yes! When added via the core TP-Link Smart Home integration in Home Assistant, the UK Tapo P304M exposes four child switch entities plus individual current power (W) and energy (kWh) sensors for each of the four BS 1363 outlets.