I'm trying to place a light switch in a sensible place in a new room being built as part of an extension. I know that according to the building regulations, the switch must be at least 300 mm from any corner of a room. But what is "a corner?"

My room isn't rectangular shape and door opens essentially against the wall - see the diagram to get the general idea. I'd like to position the switch where red dot is. Yet it would be only about 80 mm from the end of that short wall. Is that allowed? If not, the only other option is to position it on the wall at the bottom of the diagram, beyond the width of the door, but that's very inconvenient, frankly.

So, it is allowed to put the switch on the left of the door in this case? And, by the way, what's the reasoning behind the 300 mm rule?

This is in the UK.

enter image description here

EDIT: Reading the Part M, it seems that I may be OK, as the document specifically states a minimum of 300mm (measured horizontally) from an inside corner. As in my case you could argue that it's not an inside corner, it may be allowed. Yet, I'd like somebody more familiar with this to confirm.

  • 1
    can you invert the door so that the hinge is at the top (in the drawing) and opens outwards? Sep 3, 2018 at 9:57
  • @ratchetfreak Unfortunately, no. The door is already a narrow one; if it opens outwards, it would make it virtually impossible to get anything of size in/out of the room.
    – Aleks G
    Sep 3, 2018 at 10:04
  • Your scheme does not imply that switching door opening will make the passage any narrower. Can you update the drawing please? Also note, that narrow doors are better to temporary take off off hinges to move dimensional things in/out.
    – Kromster
    Sep 3, 2018 at 10:32
  • I should have mentioned that the drawing is not to scale. On the outside of the room, the distance from the door frame to the corner is about 100mm.
    – Aleks G
    Sep 3, 2018 at 10:37

2 Answers 2


That is not an "inside corner" so it looks to be allowed.

A switch at the point of the red dot seems to make the most sense and would be, in my opinion, where someone would "look" for it in the dark, etc.


Switch outside

Could you consider putting the switch out of the room?

This is usually not a problem if the room is anything else from a sleeping room (bath, storage, workshop). You might need an indicator on the switch to show from outside if the light is on inside.

It is sometime even a better design. For example if the room is specially wet, you have less electric stuff in it that might get in trouble. Also when the room is very dark (no windows), you can turn the light on before entering instead of searching for the switch in the dark.

Your case

If you could do that, put it on the wall on the left when you face the door from outside.

  • Thanks, but in my case this is a sleeping room.
    – Aleks G
    Sep 3, 2018 at 11:38

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