The standard 13-amp double socket has barely changed since the 1960s — but the devices we’re charging have changed entirely. USB-A and USB-C sockets built into the wall outlet remove the need for bulky adaptor plugs, and smart sockets add remote switching, energy monitoring, and scheduling on top of that. Neither requires wholesale electrical work; most replacements involve swapping a front plate on an existing back box.
Here’s what the different products actually cost, what they can and can’t do, and when you need a qualified electrician.
Types of USB Socket
USB-A Only
The first generation of wall-mounted USB chargers uses dual USB-A ports alongside the standard 13-amp outlets. Output is typically 2.4 A per port (about 12 W), which is fine for older phones and tablets but not adequate for modern devices. These are still widely sold and represent the cheapest option.
USB-A and USB-C Combined
Increasingly common as USB-C has become the dominant connector standard. Most units offer one USB-A and one USB-C port, with the USB-C port delivering USB Power Delivery (PD) at 18–45 W — fast enough to charge a laptop at a useful rate. Some premium units now include dual USB-C.
Smart Sockets
Smart sockets include either individual switched outlets or a whole-unit smart function, controlled via an app and/or voice assistant (Amazon Alexa, Google Home). They typically connect via 2.4 GHz Wi-Fi or Zigbee. Features vary:
- Remote switching — turn on/off anywhere via app
- Scheduling — set times for devices to power on/off
- Energy monitoring — see real-time and historical consumption in kilowatt-hours
- Voice control — via Alexa, Google Assistant, or Apple HomeKit
| Type | Typical Output | Cost (unit only) | Notes |
|---|---|---|---|
| USB-A twin (basic) | 2 × 2.4 A / 12 W | £15–£25 | Fine for older phones/tablets |
| USB-A + USB-C (standard) | Up to 30 W USB-C | £25–£45 | Best all-rounder |
| Dual USB-C (PD) | Up to 65 W | £40–£65 | Good for laptops |
| Smart socket (no USB) | Switched 13 A | £20–£60 | Energy monitoring, scheduling |
| Smart socket + USB | Switched 13 A + USB | £40–£90 | Full feature set |
Will It Fit My Back Box?
Almost all UK sockets use a standard 35 mm single gang or 35 mm double gang back box. The complication with USB/smart sockets is depth: standard front plates are 6–9 mm deep, but USB and smart units often need 25–35 mm behind the plate for the electronics. This means:
- Steel back box (35 mm depth): fits nearly all USB sockets without modification.
- Dry-lining (plastic) back box: typically shallower at 25–35 mm; some USB sockets won’t fit without replacing the back box for a deeper version (35–47 mm).
- Flush back box in a solid wall: 35 mm is standard and almost always fine.
If you’re fitting into a plasterboard dry-line wall and the socket is more than 8 years old, it’s worth taking the front plate off first to check the box depth — a replacement 47 mm dry-line box costs around £2 and takes ten minutes to swap.
Can You Fit It Yourself?
This is one of the more contested areas of DIY electrical work in the UK. The key rule under Part P of the Building Regulations (England and Wales) is that like-for-like socket replacements are not notifiable work and may be done by a competent homeowner. Replacing a single socket front plate with a USB variant in the same back box is legally a like-for-like substitution.
However, there are limits:
- Installing a new circuit, adding new sockets on a new spur, or running new cable requires either a Part P registered electrician or self-notification to Building Control.
- Work in kitchens and bathrooms near water sources has additional restrictions.
- If you’re uncomfortable working with mains electrical equipment, hire a registered electrician (NICEIC, NAPIT, or Elecsa registered). A typical single-socket swap costs £50–£120 including labour.
Always isolate the circuit at the consumer unit before removing any socket faceplate, and test with a non-contact voltage tester before touching any wiring.
Smart Socket Ecosystems
If you’re fitting more than one or two smart sockets, it’s worth choosing an ecosystem and sticking to it, as mixing brands can mean juggling multiple apps.
- Amazon Alexa / Ring — widest device compatibility; works with nearly all smart socket brands.
- Google Home — solid integration; most brands support it.
- Apple HomeKit — fewer compatible devices but a higher security standard (local processing, no cloud dependency). Expect to pay a premium for HomeKit-certified sockets.
- Matter / Thread — the emerging open standard. Matter-compatible sockets will work across all major ecosystems. Look for Matter 1.0 or 1.1 certification if future-proofing matters to you.
Zigbee-based sockets (requiring a hub) offer more reliability than Wi-Fi in signal-dense environments and don’t depend on the cloud. Good option for a whole-home smart setup.
Energy Monitoring: Is It Useful?
Energy monitoring sockets report consumption in real time and store historical data. For always-on appliances — fridge-freezer, chest freezer, NAS, fish tank, old TV on standby — this is genuinely useful for identifying what’s costing you money. A 150W device running 24/7 costs roughly £200 per year at 2026 average UK unit rates (~38p/kWh). Knowing that is the first step to addressing it.
For phone chargers and lamp circuits, the monitoring is less meaningful; those loads are small and intermittent.
Installation Tips
- Label your consumer unit before you start so you know which breaker to isolate.
- Take a photo of the existing wiring before removing any cables — USB sockets have the same terminals but often in a slightly different arrangement.
- Check the earth wire is properly terminated. USB sockets with metal faceplates must be earthed.
- Don’t overtighten the faceplate screws on dry-line walls — you can crack the socket or pull the back box loose.
- Test on multiple devices before declaring the job done; some cheap USB socket units have poor voltage regulation that can cause slow charging or intermittent faults.
Smart Sockets and UK Wiring Rules
Smart sockets that have on/off switching but remain permanently connected to mains supply count as standard socket outlets under BS 7671 (the IET Wiring Regulations). No special rules apply beyond the normal installation requirements. The smart element is just low-voltage electronics sitting behind the 13-amp outlet — it doesn’t change the nature of the installation from a regulatory perspective.
Cost Summary
| Job | DIY (materials) | Professional supply & install |
|---|---|---|
| Single USB-A+C socket, one room | £25–£45 | £80–£140 |
| Four double sockets, USB throughout | £120–£200 | £300–£500 |
| Four smart sockets (Wi-Fi) | £120–£250 | £320–£550 |
| Smart socket + energy monitoring, 6 units | £200–£400 | £450–£750 |
For most homeowners, USB sockets are a satisfying afternoon project that makes real quality-of-life difference — bedside charging, kitchen surfaces, home offices. Smart sockets are worth the premium if you have always-on loads you want to monitor or automate.
