Extending a length of 2.5mm cable - what are the regs ?

[HawkEye244]

Hi all, I have some short lengths of 2.5mm and I'm adding a double socket in ring to my lounge. It would be nice to use the cable I have already have which would require connecting two shorter lengths together. I was thinking a standard terminal strip with insulation tape, or is there something more prominent I should be using instead?

I ran a lot of cables at my place with the help of my old sparky mate whose sadly passed; otherwise I would ask him. When we worked on my house he was very keen on there being unbroken cables between sockets, so that's the reason I don't already know the answer to this.

An EICR is due soon. So I was planning to do this and then get it signed off. I just wanted to know the regs as I would like to comply with them.

 

[motorbiking]

Have you thought about adding an additional socket?

Otherwise It will need to go in to a maintenance free junction box - I think.

 

[EFLImpudence]

Buy some more cable.

 

[bernardgreen]

or is there something more prominent I should be using instead?

To be blunt, use new cable without a hidden joint .

 

[HawkEye244]

Ok thank you for the responses.
I am going to deduce from this that it is perfectly acceptable but not considered best practice.

On this occasion I'll be making the use of the cable I've already got and use a chocbox or similar to protect the terminal strip.

Thanks guys.

 

[plugwash]

As a general rule, joints should be inside an enclosure and should be accessible for inspection. If the joints will not be accessible for inspection then a maintenance free junction box or other allowed method of making hidden joints should be used.

Joints that are not located in obvious places (e.g. at a switch or at a light fitting) are a PITA for fault-finding as those doing the fault finding are unlikely to be aware of their location, or even of the fact they exist. Most electrical installations do not have detailed and accurate records kept.

 

[opps]

If you are adding a double socket as a spur, then why not just order the correct length of T&E on ebay/etc. If you are extending the ring, using short lengths and screw down terminal blocks, you risk, in time the screws working loose and breaking the ring- the sockets will still be powered but you may set fire to the cables.

Sorry, I don't want to sound harsh but in the unlikely event of a house fire which kills someone, would you feel good about saving a couple of quid?

 

[flameport]

I am going to deduce from this that it is perfectly acceptable

It's not acceptable at all.
Joints made with screw terminals must be accessible, have suitable strain relief for the cables and be made inside a suitable enclosure.

use a chocbox or similar to protect the terminal strip.

Use that if you want, but it must remain visible. Concealing it in the wall, floor or anywhere else is not acceptable.

 

[SUNRAY]

Total botch in my opinion.

What sort of length are you talking about?
6 previous replies befor mine;
4 negative replies
2 giving advice on how to do the job properly

Not a single reply confirming your proposals are acceptable...
What does that tell you?

 

[winston1]

If you are adding a double socket as a spur, then why not just order the correct length of T&E on ebay/etc. If you are extending the ring, using short lengths and screw down terminal blocks, you risk, in time the screws working loose and breaking the ring- the sockets will still be powered but you may set fire to the cables.

Don't exaggerate and scare monger. I agree it is not right what the OP is proposing but a broken ring will not set fire to the cables. A ring is protected by a 32amp MCB. 2.5mm cables will not catch fire at 32 amps.

 

[bernardgreen]

A ring is protected by a 32amp MCB. 2.5mm cables will not catch fire at 32 amps.

Winston1 has overlooked the fact that current through a resistive joint can create a lot of local heating in the cable. This can result in the cable's insulation becoming carbonized and conductive. This would then likely trip the RCD. Fault finding that would be a nightmare,

 

[opps]

Don't exaggerate and scare monger. I agree it is not right what the OP is proposing but a broken ring will not set fire to the cables. A ring is protected by a 32amp MCB. 2.5mm cables will not catch fire at 32 amps.

I wasn't intentionally exaggerating. If 2.5mm can safely handle 32amps, why is a 2.5mm radial only rated at 20 amps?

 

[winston1]

I wasn't intentionally exaggerating. If 2.5mm can safely handle 32amps, why is a 2.5mm radial only rated at 20 amps?

It doesn't have to be. It can be 25 amps. The cable is rated up to 27amps depending on installation methods. It won't instantly catch fire above that value.

 

[winston1]

Winston1 has overlooked the fact that current through a resistive joint can create a lot of local heating in the cable.

It can. But do the joint properly and it won't.

 

[SUNRAY]

Don't exaggerate and scare monger. I agree it is not right what the OP is proposing but a broken ring will not set fire to the cables. A ring is protected by a 32amp MCB. 2.5mm cables will not catch fire at 32 amps.

I'd like to receive £1 for every overheated joint I've encountered. Admittedly not all of them have progressed to a fire but all of them have caused problems of some sort.

Choc bloc in particular is often of very poor quality or badly installed. I've encountered so many problems (yes including fires) with choc bloc/2.5mm² that I will simply try to avoid it and will advise others to do the same. Anyone asking on a forum such as this (and OP is a classic example) is likely to not be aware of the issues.