Crimps on Aluminium twin and earth cable.

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!

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!