To crimp or not to crimp

[Greenie9657]

Hi everyone.

Having recently moved into my house just about every socket/switch I take off the wall has some dodgy connection behind it. I've used junction boxes and choc blocks before but now I need to sort something that's inaccessible. I'm competent at crimping, soldering, splicing etc but never done it on house wiring before. I've got the rachet tool I just need to buy the crimps/splices. Can anyone recommend a good supplier? And what crimps will I need? While I'm buying I might as well get some for 2.5 and 1.5 mm2. I'm bound to need them for a lighting job when I get into the attic.
When I've crimped at work we always stagger the joins, does the same principals apply to house? We always crimp and then heat shrink the crimp but I've read about insulated crimps. Would they be better to use?

Many thanks

 

[JohnD]

Inside a backbox, staggering is less important as the cores will not all be lying next to each other. Insulated crimps are usual but you can get them with heat-shrink as well which AFAIK will do nothing but good. Cables inside boxes do not get moved much.

Do not cut the cores back more than necessary.

 

[Greenie9657]

That's great John, thanks. I know about the conductor cutting, I don't want exposed copper out of the back. Do you know anywhere decent I can buy them? Are they called BUTT splice? The ones I'm familiar with are inline splice but I think it's the same thing.

 

[bernardgreen]

Which is best for mains wiring.

Ends of the wires touching where the electrical path is Wire 1 to crimp tube, crimp tube to wire 2.

or the wires side by side and in contact with each other where the crimp tube is only providing the compression and is not the main part of the electrical path the two wires.

 

[Greenie9657]

Would these be the ones I need for ring main wires.

http://www.tlc-direct.co.uk/Products/CTBUTTslashB.html

Thanks.

I'm happy crimping I just need to find the right crimps now. I've never used these insulated ones before. Does that mean you don't need to heat shrink?

 

[JohnW2]

... or the wires side by side and in contact with each other where the crimp tube is only providing the compression and is not the main part of the electrical path the two wires.

Are there crimps which facilitate this?

Kind Regards, John

 

[bernardgreen]

Yes

Solistrand make them http://www.te.com/catalog/feat/en/s/11178

There are other suppliers.

Using the correct tool is very important.

 

[JohnW2]

Yes Solistrand make them http://www.te.com/catalog/feat/en/s/11178 There are other suppliers. Using the correct tool is very important.

I must say that, unless these (and the tool) are very clever, I would be a bit sceptical about the concept. I would have thought that achieving effective maintained compression between the two conductors whilst at the same time satisfactorily crimping them ('to the crimp') would be a pretty tall order.

Kind Regards, John

 

[Greenie9657]

What would any of you recommend for the use on ring main, lighting and while I'm at it 6mm cabling?

 

[THRIPSTER]

Why not try Wago connectors in the back box? Simply bare the wire ends, insert cables and snap the lever shut. Look up lever clamp connectors on the appropriate web site. Much easier if room is limited.

Regards

 

[Greenie9657]

Why not try Wago connectors in the back box? Simply bare the wire ends, insert cables and snap the lever shut. Look up lever clamp connectors on the appropriate web site. Much easier if room is limited.

Regards

Hi

Thanks for you reply. As I've never used these or even seen them is it as simple as just push 2 wires into the holes and pull the lever? I've just had a look at screwfix.

 

[JohnW2]

Thanks for you reply. As I've never used these or even seen them is it as simple as just push 2 wires into the holes and pull the lever? I've just had a look at screwfix.

Yes, it's as simple as that. Some you just push in, others have the lever. However, uless they are installed in a 'Wagobox', they have to remain accessible.

I'm a little confused about the discussion that has arisen. In your original message you said "...now I need to sort something that's inaccessible", but people have been talking about connections within backboxes, which tends to imply accessibility. If the join is truly going to be inaccessible, then it either has to be crimped/soldered or use an accepted 'maintenance-free' junction box - the only two examples of which I'm aware being the Ashley 'maintenance-free' junction boxes (which also use push-in connections) and Wago connectors in a Wagobox.

Kind Regards, John

 

[Greenie9657]

Hi JohnW2

I was thinking this is going away from the OP. Due to the access my only 2 options are solder and crimp. I don't use solder unless a crimp is unavailable. As I prefer that compression connection. I was just after knowledge on what crimps to use and where best to buy them.

Regards

 

[JohnW2]

Hi JohnW2 I was thinking this is going away from the OP. Due to the access my only 2 options are solder and crimp. I don't use solder unless a crimp is unavailable. As I prefer that compression connection. I was just after knowledge on what crimps to use and where best to buy them.

Fair enough - but, as I said, 'MF junction boxes' are theoretically a possibility, even if they are to be inaccessible - are you saying that the situation is such that you couldn't accommodate them?

As for crimps, certainly go for insulated ones. They are available 'everywhere' and, although I'm sure that some people will disagree, I'm not sure that it makes much difference which you get.

Kind Regards, John

 

[bernardgreen]

If the cabling needs a lot of joints being re-made then maybe the cabling needs to be replaced rather than patched up with a collection of crimps and/or soldered joints.

Parallel crimps do not rely on the metal of the crimp for electrical connection. The connection is direct wire to wire with a contact area several times that of the cross sectional area of the wires. The compressed sleeve provides the mechanical compressive force to hold the wires against each other. In a well designed system the compressive force during the crimping is enough to produce an area of cold weld between the wires.