Plug socket with large terminals

[JohnW2]

As I asked: why would that be necessary - or needed? 3 x2.5mm conduc

I don't really unserstand your problem. It's surely useful to know that a terminal has been designed (and tested) to be able accommodate 'at least' (I.e. 'a minimum of') 3 x 2.5mm² conductors or 2 x 4mm² ones ("and maybe more, but no guarantees"). isn't it? How else would you describe the capacity of the terminals?

How is that relevant?

It's relevant as a close analogy. Just as with the terminals, it's very useful to know that a rope has been designed (and tested) to withstand 'at least' (i.e. 'a minimum of') 100kg ("and maybe more, but no guarantees"), isn't it?

Kind Regards, John

 

[EFLImpudence]

I don't really unserstand your problem.

Because it has been stated that the requirements are part of BS1363; i.e. compulsory. Why?

It's surely useful to know that a terminal has been designed (and tested) to be able accommodate 'at least' (I.e. 'a minimum of') 3 x 2.5mm² conductors or 2 x 4mm² ones ("and maybe more, but no guarantees"). isn't it? How else would you describe the capacity of the terminals?

Yes, merely useful and a description; not a compulsory requirement.

It's relevant as a close analogy. Just as with the terminals, it's very useful to know that a rope has been designed (and tested) to withstand 'at least' (i.e. 'a minimum of') 100kg ("and maybe more, but no guarantees"), isn't it?

It is not a close analogy.

Apart from being the opposite to the subject in question, It is not compulsory to manufacture rope to such a specification.

If it were, then trying a heavier load would be foolish; if larger conductors fit in the socket terminals, then it matters not.

 

[JohnW2]

Because it has been stated that the requirements are part of BS1363; i.e. compulsory. Wh y?

Maybe we've been talking at cross purposes, then.

I thought you were merely commenting on the language (as you not infrequently do on Friday evenings ) - such that you could take plugwash's use of the word 'minimum' to imply that one was 'not allowed' to put fewer, or smaller, conductors in the terminal than the figures indicated by BS1363 and/or manufacturers!

If you're asking why BS1363 says anything about what conductors should fit into terminals, you'd have to ask the authors - but it doesn't seem unreasonable that there should be a requirement for the terminals to be "fit for purpose" (as normally/commonly used).

Kind Regards, John

 

[dannyboi2003]

As above, I'm trying to replace a socket and the existing cable is too chunky to fit into the new socket I have. I'm struggling to find anything with noticeably bigger terminals. Any suggestions of something appropriate would be much appreciated.

Contactum sockets have nice large, round and deep terminals on them, they'll easily accommodate 3 x 2.5mm cables, 2 x 4mm etc. Still British made I believe and are my go to brand for white accessories when working to a budget. Normally I'd use Hager as they do look and feel more premium but the terminals on their sockets are a bit pants.

 

[Ramrod4]

Just to update this FWIW - I got a cheap MK as suggested and managed to get it to work. Thanks for the advice.

 

[plugwash]

If the standard in fact stipulates that the terminal must accommodate three 2.5mm² solid conductors, then obviously it will accommodate two 4mm²

If it's one big terminal that is probably true. However I am pretty sure sockets with multiple independent terminals for each pole are allowed (though uncommon).

That must be just guidance (not related to the actual size) because if the (assuming round) terminals will take 2 x 6mm² or 3 x 4mm², then obviously they must take 4 x 2.5mm².

Obviously 3x4mm² is a total of 12mm² while 4x2.5mm² is only 10mm².

Increasing the number of conductors (while keeping the total CSA the same) does raise a couple of issues though.

1. Conductors for mains wiring are insulated with quite thick insulation. So while the terminal itself may have the capacity, the terminal entry may not.
2. Increasing the number of wires increases the chance of getting into a bad mechnanical configuration where the terminal tightly grips some wires while others are left loose.

I have never seen a manufacturer endorse more than 3 conductors in the same terminal and I suspect there are good reasons for that.

 

[JohnW2]

If it's one big terminal that is probably true. However I am pretty sure sockets with multiple independent terminals for each pole are allowed (though uncommon).

Do any still exist? There used to be things like this (which I rather liked), but I haven't seen any on offer for decades ..

I have never seen a manufacturer endorse more than 3 conductors in the same terminal and I suspect there are good reasons for that.

There are a good few examples in the MK catalogue, albeit commonly for 1mm² or 1.5mm² conductor (with the 2A sockets said to accomodate up to 7 x 1mm² !), for example:

... but there are at least some terminals said to accommodate 4 x 4mm² :

Kind Regards, John

 

[EFLImpudence]

If it's one big terminal that is probably true. However I am pretty sure sockets with multiple independent terminals for each pole are allowed (though uncommon).

I don't follow your train of thought.

If a socket has three terminals for each pole, then each is obviously unlikely only to be big enough for one 2.5mm² core. I.e. only 1.8mm diameter (or square) if it is 2.6mm diameter (less for square/rectangle) then it will take a 4mm².

Obviously 3x4mm² is a total of 12mm² while 4x2.5mm² is only 10mm².

Q.E.D.

Increasing the number of conductors (while keeping the total CSA the same) does raise a couple of issues though.

Does it? What do you mean?

1. Conductors for mains wiring are insulated with quite thick insulation. So while the terminal itself may have the capacity, the terminal entry may not.

It might not - or it might.

2. Increasing the number of wires increases the chance of getting into a bad mechnanical configuration where the terminal tightly grips some wires while others are left loose.

Don't forget that three 4mm² wires have twenty one strands.

I have never seen a manufacturer endorse more than 3 conductors in the same terminal and I suspect there are good reasons for that.

Above?

 

[plugwash]

Do any still exist?

The only current one i'm aware of is the MK rapid fix with three level style terminals per pole.

 

[JohnW2]

The only current one i'm aware of is the MK rapid fix with three level style terminals per pole.

Yes, that's a pretty recent innovation which I hadn't thought about. However, I think it remains true that I haven't seen any with more than one set of screw terminals (which is what we've been discussing) for decades.

Kind Regards, John