An unsheathed wire

[morqthana]

... kitchen refurbishment ...

Hard to have too many sockets in a kitchen.

Might installing an extra one alongside this one be helpful if it allowed the two spurs (assuming they are) to be split?

 

[endecotp]

There are a few sockets that claim to accept 4 x 2.5mm² cables, here’s one:

https://assets.cef.co.uk/downloads/pdg/scolmore_prw036_datasheet/scolmore_prw036_datasheet.pdf

As others have said, you need to investigate why there are four cables there as it is unusual. You cannot use the socket you have bought. You do have four earths; one of the sleeves has two wires in it, and the bare wire is also an earth.

 

[JohnW2]

There are a few sockets that claim to accept 4 x 2.5mm² cables, here’s one:

Thanks. I have to say that, like Pete, I was 'sure' (clearly incorrectly!) that MK ones claimed to be able to accommodate 4 x 2.5 mm² conductors. However, most (maybe all?) do claim to accept 3 x 4 mm² conductors - and if that is true, then, at least as far as physical 'fiiting' is concerned, they ought to be able to accommodate 4 x 2.5 mm² conductors.

By calculation, 4 x 2.5 mm² (solid and round) conductors require a minimum (circular) terminal aperture of about 4.30 mm. For a hypothetical (not in T+E) solid/round 4mm² conductor the minimum (circular) aperture is about 4.87 mm. For the actual (7-stranded) conductors seen in 4mm² T+E, approximate calculation indicates (assuming strands remain circular is cross-section) a minimum (circular) aperture of about 5.52 mm.

This means that a terminal which can accommodate 3 x 4 mm² conductors ought to be able to easily accommodate 4 x 2.5 mm² ones even if the 4 mm³ one were (hypothetically) solid and certainly if (as in T+E) the 4 mm² conductors were stranded - and that would be true if the terminal aperture were square rather than round. I can't be certain how good the 'electrical connection' would be, but I suspect it would be OK, particularly given that the conductors can (and do) squash a little when the terminal screw is tightened.

These figures are illustrated in the (roughly to scale) diagram below. For a little fun, and of little other than academic interest, it would seem that a circular apperture which could accommodate 3 x 4 mm² 7-stranded conductors could probably also 'accommodate' no less than seven 2.5 mm² ones - see second diagram below

... and, as I said, "for fun" ....

I hope I've got that all roughly right, but please let me know if you don't think I have

 

[plugwash]

One issue is that the insulation tries to force the conductors apart, so even if the conductors themselves will fit in the terminal, actually getting them in can be a challenge. I've particularly found that what I can get in a terminal when I have completely free access and unconstrained can be very different from what I can get in that exact same terminal when working in an awkward location with constrained wires.

Still, I've mostly found this to be an issue with grid type stuff, for regular domestic sockets I very much doubt that 4x2.5mm ²would be an issue.

 

[JohnW2]

One issue is that the insulation tries to force the conductors apart, so even if the conductors themselves will fit in the terminal, actually getting them in can be a challenge. I've particularly found that what I can get in a terminal when I have completely free access and unconstrained can be very different from what I can get in that exact same terminal when working in an awkward location with constrained wires.

Yes, very much so - as you say, the insulation can get seriously 'in the way' - which, as you also say, becomes even more of a challenge if access is limited or, even more so, if there is a 'constraint' (e.g. terminal 'hole' at the end of a 'tunnel'. It's not unusual to see rather worryingly large amounts of bare copper outside of a terminal for this reason.

 

[robinbanks]

Hard to have too many sockets in a kitchen.

Easy* to have not enough current carrying capacity in a kitchen, mind

Give it its own ring if rewiring

(*..er than any other room in the house)

 

[pete01]

Or a 4mm radial or two

 

[ebee]

The ones I used to use could accomodate two conductors (my pref was two on a ring doubled over and the one for a spur single witout much actual difficulty thereby 5 conductor diameters. Before a slight re-design it was 6 total so each of the 3 could be doubled over. In both cases for a ring would be doubled and the single leg of the spur would be quadrupled - essentially towards the ideal aim of nearly filling the terminal hole with conductore therefore efficient surface are of contact for current carrying properties.
Seemed to work well with no problems.

I reckon it`s usually possible to treat the stated numbers a a minimum for easy connection and in practice, with a little care, can accomodate a little bit more quite often.

I do have a dislike of empty space inside a terminal.