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How to use a cube extension lead

Updated: 23 October 2026

The cube is already on the desk, and the question is what you can run before the case gets hot. This is how to use a cube extension lead in a UK home: where it sits, how the 13 A budget adds up, what the switch does, and when you unplug. It assumes you have chosen a unit. If you are still deciding between a strip and a cube, use [cube extension lead vs strip](/hub/sockets-and-extension-leads/power-cube/sub/power-cube-vs-strip). The listings are on the [power cube comparison](/hub/sockets-and-extension-leads/power-cube). Peter F. is the DIY & tools editor. These products were not lab-tested. A qualifying purchase can earn a commission at no extra cost to you.

The cube is already on the desk, and the question is what you can run before the case gets hot.

Our top picks

BEVA BEVA 4-way cube with 3 USB

Best overall

BEVA BEVA 4-way cube with 3 USB
8.9/10about £13.59
View offer
JSVER JSVER 3-outlet cube, 2 m

Best value

JSVER JSVER 3-outlet cube, 2 m
8.7/10about £13.99
View offer
JSVER JSVER 4-way wall cube

Alternative

JSVER JSVER 4-way wall cube
7.8/10about £12.99
View offer
On this page
  1. 1.Before you plug anything in
  2. 2.Place the cube
  3. 3.Use the switch and the USB ports
  4. 4.Stop and unplug
  5. 5.When a professional takes over

Before you plug anything in

Read the mark before the first device goes in. A 13 A fuse in a BS 1363 plug is the total for every mains face. A four-face cube is not a 52 A hub. Electrical Safety First says to add what may run at once, use one extension per wall socket, and not daisy-chain. A kettle can be up to 13 A, about 3,000 W, and can fill the cube alone. USB watts do not increase that fuse. If BEVA or JSVER prints 13 A and 10 A, plan against the lower figure until you read the moulding. The cube goes into the wall. The JSVER wall cube is the plug. One cube, one socket, one budget.

Place the cube

Put a cabled cube on a hard, dry surface you can see. Keep the lead out from under a rug. There is no reel to unwind. Flex here runs from the Status 1.4 m lead to a claimed 2 m. If it is tight, move the cube. Do not stretch it. The JSVER wall cube has no flex, and reviews say it walks out under plug weight. Which? describes the same failure: poor contact, then hot pins. Use light plugs and look again after an hour. Do not put a kettle on it. That choice is on the cube extension lead buying guide. No kept listing prints an IP rating.
BEVA BEVA 4-way cube with 3 USB

Testsieger

BEVA BEVA 4-way cube with 3 USB
8.9/10about £13.59
View offer

Use the switch and the USB ports

Most cabled cubes have a master switch: BEVA on the top, ROOTOMA and VoltFlow with an indicator, and Fellowes with an on/off button. Status bullets omit one, though reviews describe it. The JSVER wall cube does not state a switch. Use it to kill standby. It does not raise the fuse, and it does not make a hot case safe. On a shared 5 V 2.4 A bank, two phones charge more slowly than one. VoltFlow's 65 W on C1 applies only when the other USB ports are empty. If ROOTOMA USB stays dead after a switch cycle, stop using that port. A case you cannot hold is not ordinary warmth.

Stop and unplug

Stop for a hot plastic smell, scorch marks, sparks, or a case too hot to hold. Unplug at the wall. Do not reset a breaker and carry on, and do not fit a larger fuse. A melted fuse on the JSVER wall cube is a failed unit. A burnt smell after a kettle and a toaster have shared the cube is overload. A charger stuck to a melted cable, as in a ROOTOMA review, means you retire that cube. A pin that arrived loose is a return.

When a professional takes over

Call an electrician if the socket is scorched, the plug is too hot to touch, or a breaker trips as soon as the cube is added. Another cube will not repair a damaged outlet. A landlord ban on block adaptors is a site rule. No kept listing prints an IP code. For a light desk load, use best cube extension lead UK.

Common questions

Can I plug this cube into another lead?
No. Electrical Safety First says one extension per wall socket and tells you not to daisy-chain. The cube's own flex, where it has one, is the lead. Plugging it into a reel or a strip stacks contacts and hides the load. If the socket is too far away, you need a longer lead of the right rating, not a second cube in series.
What if the case is hot?
Unplug it at the wall and leave it to cool where you can see it. A case too hot to hold, a hot plastic smell, scorch marks or sparks are the Electrical Safety First danger signs. Do not put the plugs back in to see if it settles. Heat reviews on the ROOTOMA cube and the JSVER wall cube are reasons to retire that unit.
Why did USB stop after I used the switch?
Some cubes drop USB when the master switch cycles. A ROOTOMA review pattern is that charging does not resume until the cable is reseated. Switch off, wait, switch on, and plug the lead in again. If the port stays dead while the mains sockets work, stop using that port. The switch has not increased the 13 A budget.
Can I leave phones charging overnight?
Prefer not to, especially on a cube with heat reports. Charge on a clear hard surface while you are around, then switch the cube off. A pillow or a cable box traps heat. VoltFlow's higher USB-C figure applies only when that port is used alone, and reviews still report failures. If the cube has already run warm, a single wall charger is the simpler tool.
When do I call an electrician?
Call when the wall socket is discoloured, the plug will not sit firmly, or a breaker trips as soon as the cube is in use. Call when you need a permanent extra socket. A cube will not repair a damaged outlet, and these listings have no IP rating, so a garden or a bathroom is the wrong job. A longer indoor lead for light desk kit is a buying choice, not a call-out.

Related pages

Wall cube or cabled cube

Power cube

Best cube extension lead UK

Cube extension lead buying guide

Cube extension lead vs strip

Sources

Sources taken from the research digest. Shelf prices, stars and review counts are the amazon.co.uk figures in the stored listings, dated 21 October 2026. This page did not run a lab test.

  1. Electrical Safety First — extension leads, cable reels and block adaptors (retrieved 22.10.2026)
  2. Electrical Safety First — overloading sockets (retrieved 22.10.2026)
  3. Electrical Safety First — ratings of electrical appliances (retrieved 22.10.2026)
  4. London Fire Brigade — cables, fuses and leads (retrieved 22.10.2026)
  5. Which? — how to avoid overloading plug sockets (retrieved 22.10.2026)
  6. Scottish Fire and Rescue Service — electrical safety (retrieved 22.10.2026)
  7. Electrical Equipment (Safety) Regulations 2016, regulation 35 (retrieved 22.10.2026)
  8. BSI — BS 1363-3:2023 adaptors (retrieved 22.10.2026)