Type M 3 Pin Sockets

ddubs

Ive recently bought a house (1920's but has been rewired) and about half of sockets downstairs are Type D or M sockets. I know these are used for lighting is some case but I'm conscious that the previous owner was South African (SA used type M as standard).

Can I swap out these with standard Irish/UK type 13 amp sockets?

Thanks for your help?

my3cents

I would check how they are fused wired and connected up first?

Check exactly what size fuse covers the current plugs and how many are on each fuse. It may be only a low rating to cover lighting.

Check what size cable is connected to the back of each plug (obviously with the power off). Again it may be lower powered cable 1 or 1.5mm rather than 2.5mm

Check if each socket is on its own spur off the fuse board part of a group of spurs or a part of a ring - the way the plugs are wired may also help indicate this.

If the cable is suitable and the fuse (mcb) in the board is a suitable rating then you should be OK to change the plugs.

The type M should be OK to change over I would expect each socket to have its own spur and fuse because there is no fuse in a type M plug which I think is why they aren't put on a ring main. Check the above to be sure first.

The type D may is more likely to have a supply (cable and fuse) not rated for a 13Amp plug.

Edit> Check also that you have earth wires and that they are connected to earth a simple tester plug will help https://www.amazon.co.uk/Meterk-Advanced-Electric-Automatic-Polarity/dp/B07C16GNSC/ (example) and also check if all the plugs you are thinking of changing are connected to the main RCD. Sometimes lights aren't and the type D may have been installed for lights.

That got complicated fairly quickly so probably best to get a registered electrician to take a look for you.

goingnowhere

Sounds like someone never replaced the original 3 pin sockets used prior to the type G standard. SA and India still use those plugs, aka BS546

Type M is the 15Amp type so swap to type G 13Amp can work, type D is 5amp so cannot be made into 13 Amp outlets unless the underlying wiring system and distribution board, fuse/RCD arrangements are correct. While the regulations DO allow for replacement of sockets, switches by non RECI this isn't a straightforward swap.

I would be surprised to find any recent rewire (i.e. since the 70's) retain the old sockets, that said the old sockets if they have safety shutters might still be legal, at least in the UK BS546 is still an active standard

Get a RECI spark out to perform a full test on the entire install, you might be in for a surprise and may have significant work.

Stoner

The main concern here would be the potential lack of earth leakage circuit protection that lighting sockets circuits dont get.

It would need a review from a REC to make sure the cabling and circuit protection is to the correct standard imo.