Independent comparisons. We may earn from shop links. More info

Socket covers vs lockable socket: blank or lock

Updated: 23 October 2026

You have a cheap plug-in socket cover in one tab and a lockable socket in the other, and both are called a cover. One is a pin that pushes into the holes of an empty UK socket. The other is a box over a plug, or a key on the switch. Only the second is a socket lock. The locks, not the inserts, are on the [socket lock comparison](/hub/sockets-and-extension-leads/socket-lock). We used BEAMA's paper of 5 June 2017, the IET Wiring Matters article updated in February 2020, MHRA alert EFA/2016/002, and Electrical Safety First, on 21 October 2026. We did not lab-test the listings. A qualifying purchase can earn a commission at no extra cost to you.

You have a cheap plug-in socket cover in one tab and a lockable socket in the other, and both are called a cover. One is a pin that pushes into the holes of an empty UK socket.

Our top picks

Knightsbridge Knightsbridge CU9LOCKN

Best overall

Knightsbridge Knightsbridge CU9LOCKN
6.7/10about £13.88
View offer
PlugMinder PlugMinder 80 mm cover

Rank 2

PlugMinder PlugMinder 80 mm cover
8.6/10about £21.99
View offer
PlugMinder PlugMinder 38 mm cover

Best value

PlugMinder PlugMinder 38 mm cover
8.2/10about £18.99
View offer
On this page
  1. 1.Two products, one name
  2. 2.What BS 1363 already does
  3. 3.What an insert can change
  4. 4.What a socket lock is for

Two products, one name

A plug-in cover, in the sense these safety pages use, is a dummy plug. You push pins into the holes so the socket looks occupied. There is no key, and nothing stays connected behind it. It only fits an empty socket. Shops still file it under socket covers. A lockable socket here is a cover over a plug that stays in, a key-lock outlet such as CU9LOCKN, or an industrial lockout such as the Marhynchus 40 mm title. PlugMinder's range page says its enclosure is not a child-safety insert. Read the picture: pins into the holes, or a door over a plug.

What BS 1363 already does

A BS 1363 socket is shuttered, so one object in one hole does not reach a live contact. BEAMA's paper of 5 June 2017 says BS 1363-2 sockets and BS 1363-3 adaptors must have those shutters, and it advises against covers pushed into them. The IET, in Wiring Matters updated February 2020, says a pin travels about 9.6 mm before live parts, and points to regulation 553.1.201 in BS 7671. Electrical Safety First says the shutters are the designed protection. A blank does not improve a sound socket. The Plugs and Sockets etc. (Safety) Regulations 1994 tie plugs and sockets sold here to that British Standard. Shutters do not keep a plug from being pulled out.
Knightsbridge Knightsbridge CU9LOCKN

Testsieger

Knightsbridge Knightsbridge CU9LOCKN
6.7/10about £13.88
View offer

What an insert can change

The IET says there is no British Standard for the protector itself. Pins that are too wide can deform the contacts. Pins that snap off can leave the shutter open. BEAMA says those inserts can overcome the shutters and introduce shock and fire risk. MHRA alert EFA/2016/002, issued on 30 June 2016, tells care settings not to use 13 A inserts and not to supply them for a home. Written answer S5W-20521 records the same alert to NHS Scotland. The alert prints valid to 30 June 2022. It is about pin-in inserts. It does not ban a clamp-on box or a key-lock socket, and it is not a criminal-offence claim for every UK home.

What a socket lock is for

A socket lock keeps a chosen plug in, locks a switch, or locks out a connector withdrawn for work. A dummy pin does none of those. A PlugMinder cover closes over a plug that stays powered, after you measure the depth on the buying guide. CU9LOCKN locks the outlet on or off. The 40 mm listing is not shown as a Type G 13 A cover. A lockable cover does not make an empty hole safer. The shutter already does that. If the worry is a plug that must not come out, measure for a cover and fit it with the circuit dead. Do not add a blank in the spare hole beside it.

Common questions

Are plug-in socket covers the same as a lockable socket cover?
No. A plug-in cover is a dummy pin in an empty socket. A lockable socket cover is a box over a plug that stays in, or a keyed outlet, or a maintenance lockout. Shops use socket cover for both. PlugMinder says its enclosure is not a child-safety insert. If there is no key and no hinge, it is not the lock.
Can a dummy plug damage the contacts?
It can. The IET says there is no standard for these protectors. Pins that are too wide can deform contacts. Pins that are too narrow can pull out. Brittle pins can snap and leave the shutter open. BEAMA says the inserts can defeat the shutters and add shock and fire risk.
Does the MHRA alert ban lockable boxes in care homes?
No. EFA/2016/002, issued on 30 June 2016 and printed as valid to 30 June 2022, tells care settings to withdraw 13 A inserts and not to supply them for a home. The alert is about pin-in inserts. A clamp-on cover or a key-lock socket is a different product. Do not read it as a ban on those locks, and do not ignore it for inserts.
Should I put a pin-in cover in an empty socket and a lock on the router?
Put the lock on the router if that plug must stay in, after you have measured the depth. Leave the empty socket shuttered. The insert does not protect the router, and the safety sources say it can make the empty socket worse. One product for one job.
What should I buy if the plug has to stay in?
Buy a lockable cover that closes over that plug, not a blank for the spare hole. In this comparison that means the cover rows on the main table, chosen by depth on the buying guide, and fitted only after the circuit is proved dead. A key-lock socket is the other purchase, and only when the outlet itself must lock on or off.

Related pages

How to fit a lockable socket cover

Socket lock

Best socket lock UK: one cover, one key-lock socket

Lockable socket cover: which kind, then plug depth

Socket lock dementia: keeping the essential plug in

Sources

Sources taken from the research digest. Listings were scored on 21 October 2026. This page did not run a lab test.

  1. Plugs and Sockets etc. (Safety) Regulations 1994 (retrieved 21.10.2026)
  2. IET Wiring Matters, socket-outlet protectors (February 2020) (retrieved 21.10.2026)
  3. BEAMA position paper on socket outlet covers (5 June 2017) (retrieved 21.10.2026)
  4. Electrical Safety First — socket covers (retrieved 21.10.2026)
  5. Electricity at Work Regulations 1989, regulation 12 (retrieved 21.10.2026)
  6. HSE HSG85 (retrieved 21.10.2026)
  7. Approved Document P (England, 2013) (retrieved 21.10.2026)
  8. CU9LOCKN datasheet — ML Accessories (retrieved 21.10.2026)