Can I spur off a radial circuit?

[Jupiter01]

I have previously spurred a socket off an existing socket that features on an ring main but wanted to check if the above is acceptable too.

My Kitchen is using 4mm T&E for its circuit. This runs the usual kitchen equipment. My oven is on a separate circuit.

Due to all the home schooling, I need to place a PC in the room behind the kitchen and I could quite easily punch a hole through the wall and spur from the socket on this particular wall.

Also, can I use 2.5mm T&E for the spur to the new socket?

Thanks in advance.

 

[ericmark]

A radial in 4 mm² from a 30/32 amp fuse/mcb/rcbo is the same as a ring final when taking an unfused spur, to quote:-

An unfused spur run in 2.5 mm² cable should feed one single, or one twin socket outlet only.

Of course any new work must comply with BS7671:2018 and I don't have a copy, but that means must be RCD protected.

 

[Taylortwocities]

If your circuit is run in 4mm², it is usual to use the same case cable for additions.

 

[Jupiter01]

If your circuit is run in 4mm², it is usual to use the same case cable for additions.

I don't have any 4mm cable but plenty of 2.5mm in the shed. That's why I wanted to check

 

[JohnW2]

I don't have any 4mm cable but plenty of 2.5mm in the shed. That's why I wanted to check

As has been said, provided it supplies only one (single or double) socket, 2.5mm² is fine (and even depicted in an Appendix of the regulations) for a 'spur' from a 4mm² radial.

As has also been said, it is arguably preferable to use 4mm² cable, just in case someone subsequently wants to extend the 'spur'/branch (to more than just the one socket) - but, so long as it is supplying only the one socket, 2.5mm is fine.

Kind Regards, John

 

[Jupiter01]

Hi Guys,

I’ve purchased some 4mm T&E for this spur as per recommendation but have a further challenge now. The source socket (MK brand) just about accepts the existing 2 lots of 4mm cables and adding a third one into the L&N terminals seems impossible. I’ve tried twisting them altogether too (as seen in image) and that isn’t working.

Can I replace this socket with one which has larger terminals perhaps?

I look forward to your advice.

 

[EFLImpudence]

Don't twist them together.

 

[JohnW2]

... I’ve purchased some 4mm T&E for this spur as per recommendation but have a further challenge now. The source socket (MK brand) just about accepts the existing 2 lots of 4mm cables and adding a third one into the L&N terminals seems impossible. I’ve tried twisting them altogether too (as seen in image) and that isn’t working. ... Can I replace this socket with one which has larger terminals perhaps? I look forward to your advice.

Ah. In my experience, MK sockets have at least as great terminal capacity as any other make (more than many makes), and I (like others) have certainly had no problems getting 4 x 2.5mm² cables into the terminals with no trouble, and would have expected 3 x 4mm² to fit. Twisting them together will make the situation worse, rather than better.

However, the specification of (current) MK sockets certainly claims that they should take 3 x 4mm². Do you perhaps have an 'old' one'

Kind Regards, John

 

[333rocky333]

Ah. In my experience, MK sockets have at least as great terminal capacity as any other make (more than many makes), and I (like others) have certainly had no problems getting 4 x 2.5mm² cables into the terminals with no trouble, and would have expected 3 x 4mm² to fit. Twisting them together will make the situation worse, rather than better.

However, the specification of (current) MK sockets certainly claims that they should take 3 x 4mm². Do you perhaps have an 'old' one'

View attachment 218940

Kind Regards, John

The socket in the OPs picture is a "Click" not an Mk as he said.

I seem to recall the older Mk Terminals with the round holes were larger than the Mk newer cage ones, I remember taking one off with about 7 wires in, I am sure i used to keep older ones on the van as they were easier to fit when we found too many wires.

 

[JohnW2]

The socket in the OPs picture is a "Click" not an Mk as he said.

Ah - I hadn't noticed that. In that case, maybe he should get and try a real MK one - since, as I said, at least in my experience (and even today), I think that they probably have at least as much terminal capacity as any other make.

Kind Regards, John

 

[Jupiter01]

Sorry guys, my bad. I purchased an MK Socket today but that was intended for the new socket I a adding onto this circuit. The socket in the picture was indeed a Click.

I have since switched this to the new MK socket I purchased today but still didn’t manage to insert 3 4mm cables into the terminals. I assume you are aware that the 4mm cables are stranded and therefore much bulkier! My situation is probably compounded by the fact that there isn’t a lot of slack in the existing cables. I conceded in the end and used 2.5mm for the spur connection.

Thanks for all your help.

 

[JohnW2]

I have since switched this to the new MK socket I purchased today but still didn’t manage to insert 3 4mm cables into the terminals. I assume you are aware that the 4mm cables are stranded and therefore much bulkier!

Yes, they are stranded, but I wouldn't have said 'much bulkier'. I'm pretty sure that I have, in my time, got 3 x 4mm² into an MK socket (as I said, I've certainly got 4 x 2.5mm² in) and, as I illustrated, the MK spec certainly claims that there is capacity for 3 x 4mm² - so I don't know what to say!

Kind Regards, John

 

[plugwash]

Ah - I hadn't noticed that. In that case, maybe he should get and try a real MK one - since, as I said, at least in my experience (and even today), I think that they probably have at least as much terminal capacity as any other make.

Anyone buying white plastic MK accessories now needs to be aware that they have two totally different ranges of them.

There is "Logic plus" which, which is still largely the same design it has been for many years, though a lot of electricians report the quality has slipped. The terminal capacity on logic plus has always been documented as 3x2.5mm², 3x4mm² or 2x6mm² and I don't think the basic size and shape of the terminals has ever changed (though the method for retaining the screws in the terminals has)

Then there is "essentials". I can't seem to find any documentation of it's terminal capacity, but it really doesn't matter as it's total crap that you should not buy.

 

[securespark]

I remember taking one off with about 7 wires in

I went to a rewire in the 80s and one MK socket I took off had 8 2.5s in it!

 

[securespark]

Then there is "essentials". I can't seem to find any documentation of it's terminal capacity, but it really doesn't matter as it's total crap that you should not buy.

2 x 4 milli