The number that matters on a USB socket is the amps, and on almost every one it's shared between the ports — not per port. A "5.1A quad USB" outlet gives you 5.1A total across four sockets, not 5.1A each.
Get that one thing straight and the rest of the decision is easy.
We fit these across the counter constantly, and the complaint we hear is always the same: "it charges really slowly when the kids plug in too." That isn't a fault. That's four devices sharing one budget.
1. Shared amps, and what it means in practice
USB outlets are rated in total output. Plug in one device and it gets the lot. Plug in four and they divide it.
So a quad outlet rated 5.1A shared is excellent for one phone, fine for two, and slow for four. That's not a reason to avoid quad outlets — it's a reason to put them where several people charge occasionally, rather than where one person needs a fast charge.
Trade Tip: for a bedside, fit a dual and be happy. For a kitchen worktop or a family landing, fit a quad. The mistake is fitting a quad at a bedside because "more is better", then wondering why a phone that used to charge overnight now doesn't when a tablet is beside it.
The Knightsbridge FPR7USB4BCW is a 13A switched socket with a quad USB charger, brushed chrome, IP20, 230V 50Hz. You keep the 13A outlet and get four USB ports in one plate.
2. Socket-with-USB, or USB-only?
Two different products, and people order the wrong one regularly.
A 13A socket with integrated USB replaces a normal socket. You still get the three-pin outlet, plus USB ports beside it.
A USB charger outlet has no 13A socket at all — it's USB only. Correct where you want a dedicated charging point and don't need mains: a bedside shelf, a desk, a hallway drop zone.
The Knightsbridge FPR9901PCW is a 13A switched socket with dual USB A+A at 2.1A, polished chrome with a white insert. Dual is the right density for most bedrooms.
If you replace a normal double socket with a USB version, you lose nothing — you keep both 13A outlets and gain the USB. That's why these are one of the easiest upgrades in a house.
3. Check the back box depth before you buy
Here's the one that stops a job dead.
A USB socket has charging electronics behind the faceplate. It is physically deeper than the socket it's replacing. Older UK back boxes are often 25mm deep, and many USB sockets want 35mm or more.
Trade Tip: before you order, take the existing socket off and measure the box depth — and look at how much slack the cable has. A shallow box with tight tails is the combination that turns a ten-minute swap into chopping plaster out. If it's 25mm, plan on changing the back box at the same time, and buy the box with the socket rather than making a second trip.
On a plasterboard wall this is easy — dry-lining boxes come in deeper sizes and clip straight in. On solid brick it means chasing out, which is a different afternoon.
4. USB-A and USB-C — being straight with you
USB-A is the original rectangular port. USB-C is the small oval one that goes in either way up, and it's what new phones, tablets and laptops increasingly use.
Every USB socket we currently stock is USB-A. They charge a USB-C device perfectly well with an A-to-C cable, which is what most people already own — but if you specifically want a C port in the wall, ring us or come in rather than ordering and hoping. We'd rather tell you straight than sell you the wrong thing.
5. Where they actually earn their keep
Not every socket needs USB. The ones that pay for themselves:
- Bedsides — the single best location. Dual is plenty.
- Kitchen worktop — quad, because everyone charges in the kitchen.
- Home office desk — frees the 13A outlets for monitors and lamps.
- Hallway — a drop zone for keys and phones.
- Holiday lets and HMOs — guests arrive without plugs, never without cables.
Where they don't: behind a fridge, behind a TV unit, anywhere nobody stands with a phone.
6. Where DIY stops
Swapping a like-for-like socket on an existing, correctly-isolated circuit is a competent DIY job. Isolate at the consumer unit, prove dead, photograph the terminals first, and note which conductors were in which terminal before anything comes loose.
Adding a new socket is a circuit alteration and needs testing and certifying. A socket in a room containing a bath or shower is a special location under Part P in England and Wales. If you can't self-certify it, get an electrician.
USB socket quick-reference
| Location | Fit | Why |
|---|---|---|
| Bedside | 13A socket + dual USB | Two devices, full speed each |
| Kitchen worktop | 13A socket + quad USB | Several users, short top-ups |
| Desk | 13A socket + quad USB | Keeps mains outlets free |
| Hallway | USB-only outlet | No mains needed |
| Behind a TV or fridge | Standard socket | Nobody charges there |
Expert Help in the West Midlands
We've been on Villa Road in Handsworth since 1975, and the counter is open to trade and public alike.
Take the existing socket off, measure the back box depth, and bring that number. It's the one measurement that decides whether this is a ten-minute swap or a plaster job, and it's the one nobody thinks to check.
Browse the range in USB Sockets.
Frequently asked questions
Do USB sockets charge slower than a plug?
With one device, generally no. With several, yes — the amp rating is shared across the ports, not per port. A 5.1A quad outlet gives one phone the full 5.1A and four phones roughly a quarter each.
Do I need a deeper back box for a USB socket?
Usually. The charging electronics sit behind the faceplate, so USB sockets are deeper than standard ones. Measure your existing box first — 25mm boxes are common in older UK homes and often need replacing.
Can I replace a normal double socket with a USB one?
Yes, and you keep both 13A outlets. Like-for-like on an existing circuit is a competent DIY job, provided the back box is deep enough and you isolate and prove dead first.