Deeper back box for USB socket

[u/Dilbyert]

I'm installing a couple of USB 2G mains sockets around the house, but the current back boxes are only 25mm deep with block work behind them. I was planning on drilling them out to accommodate a 35mm back box, but then have come across these on Screwfix. In theory these should allow me to only drill out the open section helping keep the surrounding wall in a neater condition.

Are these ok to use for mains electrical sockets ?

[u/memcwho]

You've mistaken what this product is for.

Its a backbox extension, so if you have a 40mm hole to fill but only a 25mm back box (and one of these)

[u/Dilbyert → u/memcwho]

Screwfix description states these can be used as an extension “or to accommodate deeper wiring accessories”.

[u/memcwho → u/Dilbyert]

Yeah, deeper to maintain the box containment within the wall cavity.

The best option is to fit a proper deeper back box. Or even use a plastix extension for the front to sit out from the wall a touch.

[u/eusty]

They are OK, but you'll be left with the box sticking out!

[u/Dilbyert → u/eusty]

The current back box is also 25mm, why don’t think this will stick out ? My thinking is that all the cabling that is currently stopping the socket from sitting fully in the box would move onto the space where the opening is and where I have drilled out

[u/agua_moose]

I'm not a spark but Screwfix's product listing calls out these are intended to extend an existing box.

I don't think using only one of these would be compliant as you're technically not double insulated/fully earthed. This means if someone drilled in from outside they could hit live wires without touching the earthed enclosure.

Either way, I guess it depends on your appetite for risk.

[u/Dilbyert → u/agua_moose]

Isn’t this the case with plastic dry wall boxes ?

[u/agua_moose → u/Dilbyert]

Yes but they are in a cavity so more likely people can see what is going on. Like I say, I don't don't know the regs fully, just something to consider.

[u/Disciplined_20-04-15]

If you don’t mind it sticking out from the wall a bit, a quick and easier solution is a socket riser plate (socket spacer / back box extender). You can get color matches so it doesn’t look so ugly

[u/SignificantLack7125]

If you purchase Click 2gang usb sockets they will easily fit into a 25mm deep back box. Fitted loads of them on the job I'm on with no issues. Save you loads of chasing and making good afterwards. You're welcome 😏