Dry Lining Box

[unigirl]

Hi All

My partner has recently connected up a new twin-gang socket in the bedroom. The wall is plasterboard and he was advised to use something called a dry-lining box. The box (and socket) are located about 30 cm above the wooden floorboards on the wall. Behind the wall is a void with the housebricks visible.

The cable goes out of the box via a square hole called, I think a knock-out, at the middle bottom edge of the box. From there, it goes down the void and into the space under the floorboard to a socket on the ring main (the new socket is a spur).The issue he has is basically, how is the twin and earth cable meant to be secured in the dry lining box? The knockout was bigger than the cable and there are no "teeth" or cable clamp in the box to hold the cable in place. Can something be improvised for the job? He doesn't think a grommet would fit in a square hole properly. On the other hand, is it satisfactory for the cable to just exit the box without it being held in place - no one is likely to pull it after all given its position.
Sorry if I've rambled on with my thoughts as well as the question!

thank you.

[malagabob]

There are YouTube videos of fitting drylineing boxes.

[unigirl]

So there are malagabob. All of them show the box being fitted in a piece of plaster board sitting on a table. None of them show how to dress the cable in the context of the question.

[unigirl]

I thought by now that a builder or electrician would have helped answer my question. Surely it can't be that difficult.

[bhg481]

Whenever I've done that job I've just let the cable dangle in the void. It must be 20 years since I last did the job and I've had no problems with it. I am NOT a qualified electrician.

[The Builder]

No cable fixing is needed in a dry-lining box. Perfectly normal.

[unigirl]

That's reassuring. Thank you all for your help.