Crimps on Aluminium twin and earth cable.

In the Electricity Supply Industry, we would not crimp aluminium in a copper connector, or the other way around. We would either use a “bi metallic” connector which has one half aluminium and one half copper, or use a brass connector. 
 

Regards,

Alan. 

Looking at the pic in post 2, and the close up in post 14-ish, the aluminium does not seem very tarnished, despite, i assume, being there since original installation. The brass-aluminium interface seems to be better than a copper-aluminium one, which is why i thought chockblocks might be a better solution.

Good thread.

Colin Haggett: 
 

Zoomup: 
 

Colin Haggett: 
 

Also blue inline crimps are only rated at 15 amps

That's all right then innit? 15 Amps per leg if it is a ring circuit protected by a 30/32 Amp device.

 

Z.

Takes a lot planning to get a perfectly balanced ring to protect those crimps.

And only a concern if the ring is fully loaded.

Z.

Colin Haggett: 
 

Zoomup: 
 

Colin Haggett: 
 

Looks like a bad repair from when it overheated at the fuse carrier. Probably best to rewire and lose all the aluminium cable and have a nice shiny new consumer unit. 

Am I right is assuming that the red shield is the type that only accepts Wylex cartridge fuse carriers and Wylex M.C.B.s? If so, the terminal must have been the cause, either a loose screw or deformed loose aluminium.

Z.

The first fault was the loose connection unfortunately badly repaired coursing a second failure to happen. 

It is doubtful that the fuse carrier was at fault as the Wylex  cartridge fuse carriers or M.C.B.s have proved to be very reliable in my experience. The carrier was not a B.S. 3036 type.

Z.

Alan Capon: 
 

In the Electricity Supply Industry, we would not crimp aluminium in a copper connector, or the other way around. We would either use a “bi metallic” connector which has one half aluminium and one half copper, or use a brass connector. 

Which rather begs the question, how are the two halves of the crimp connected? (I am aware that it is possible to weld dissimilar metals, or just solder them.)

Which rather begs the question, how are the two halves of the crimp connected? (I am aware that it is possible to weld dissimilar metals, or just solder them.)

Bi-metal Crimp Connector from China manufacturer - Socome, power equipment & lightning protection products manufacturer (socomepower.com)

Friction welding

Interesting comments Gentlemen but you have missed the problem I see that is really quite serious.  The crimps are not crimped properly with the correct tool, anyway even if done properly aluminium conductors are a big snag in small sizes. I am not at all happy with Wagos on an aluminium cable either. If you crimp ali cable I expect you to coat the surface with the correct paste, and to use the correct crimp tag and the correct tool. Exposed aluminium forms a surface oxide layer, and this is quite capable of forming in a contact area although you may think it is “gas-tight”, and therefore will stay clean and clear. This is NOT the case, aluminium oxide will continue to form in the depth of the material, particularly if subject to temperature cycling as the oxide is very brittle. The aluminium joint paste is very important in aluminium cable connections of all sorts to prevent oxide migration, even if they are big sizes (500 mm2) with correctly applied crimp tags that have very large deformations. It could not be used in a Wago because there is no access, and even a chock block would probably not last well. With the correct crimp (manufacturer very important, not Chinese Cheap) and the correct tool copper joints in solid cables are satisfactory, but often the wrong parts and tools result in Andy's photos above. I would code aluminium T&E as C3 if undamaged and C2 if any of the problems are there, wrong tool, wrong make of crimp etc. without visible damage. Any of the signs of heat and this is a C1. Experience is the key, although many think I am too generous with other things, this is a fire waiting to happen as you can see from Andy's pictures. I wonder what the “books” say for this?

Added: Aluminium oxide is an excellent Insulator!

AdrianWint: 
 

Personally I don't like to see those kind of crimps on solid core cable. 

I was taught that they are intended for multi-strand cores.

Definitely you need to check with the manufacturer's info with the red/blue/yellow crimps - some (very few) are suitable for class 1 (single solid). Some are stated as only being suitable for class 5 and 6 stranding (flexible and extra-flexible). Most of them will will be OK for stranding class 2, 5 and 6 conductors though.

I am not recommending these or saying that they are suitable, but they do claim a 27 Amp rating, perhaps with a following wind.

27A Blue Butt Splice Wire Connector - Pack of 100 - Unbranded | CPC UK (farnell.com)

Z.

I can't see the use of any paste here. The joints are good. Perhaps the whole thing is protected from moisture by a resin encasement.