Copper Clad Aluminium CCA Terminating methods

Joined
1 Oct 2007
Messages
607
Reaction score
22
Location
Hampshire
Country
United Kingdom
In the process of re-modeling the kitchen and have stripped out all sockets and intermediate cables. I'll re-run the new stuff in 2.5mm T&E, but the existing ring is 4mm copper clad alu. And it sucks.

The ring impedances measure fine for the rest of the house, insulation is in good condition and measures fine too, so don't need to do a full re-wire.

I've already had a few core strands tear up when torquing the accesories, and would like to do something to toughen them up prior to doing up any more.

What would peoples suggestions be to do this?

I've tinned one core and it has 0 breakage, but still has quite a lot of deformation. I'm also going to experiment with a ferule, but hesitant to clamp that under a screw.

Cheers,
Fubar
 
Sponsored Links
Are you sure it's not tinned copper?

Do not solder the wire ends if terminating into screw terminals. It's against regs and WILL lead to a failed connection.
 
Yup. States Copper Clad Aluminium down the length and is ridiculously soft and light.

Huh, did not know that one. What's the reasoning behind the failure? mechanical stress, chemical incompatibility... etc?

Fubar
 
Results of termination tests:


Left to right
1) CCA cable, fresh from a strip.
2) Lightly torqued in a screw fitting, note the broken strand.
3) Soldered and torqued (NOT COMPLAINT), improved mechanical response, but still a lot of deformation.
4) Crimped with a ferrule. Improved deformation, solid looking connection.

Fubar
 
Sponsored Links
Seem to remember during the Ian Smith Rhodesia crisis we had clamps not screws to grip the cables. The smaller aluminium were a failure and once we got the copper supply back they were dropped. Larger cables are still aluminium but with a solid core not stranded.

At the time I was an auto-electrician and with 12 and 24 volt we actually had cables explode. Using these
C448064-63.jpg
with calibrated crimp pliers is likely the best way but in all my years as an electrician only one firm has ever calibrated the crimp pliers that was GEC Large Steam Turbines and I have not a clue how they are calibrated just know we sent them away every 6 months to be adjusted. It also resulted in separate crimp pliers for 1mm, 1.5mm, 2.5mm, 4mm, and 6mm the standard crimp pliers with three sections for red, blue and yellow were not permitted although they do have a scroll to calibrate with.

Personally I would want to re-wire ASAP as I have seen the problems I was around during the Ian Smith Rhodesia crisis and the stand off with HMS Sheffield and have seen the problems with stranded aluminium cables.

But do wait for other replies.
 
Re-wiring would be pretty destructive to the otherwise freshly decorated house. Cables, as far as pure conductors go, look alright. Just the termination that's a pain.

Not a fan of those crimps. I get why they're used, but at least with a ferrule, you are clamping on the wire itself, albiet, through another layer of metal.

Tempted to solder some solid copper singles to the CCA in each backbox and terminate on the singles.

Fubar
 
It is the flux which is a problem with solder. I know you can get special aluminium flux but slightest bit of flux left can eat into the cable. Specially with lead free.

Some 13A sockets have a terminal where the screw moves a clamp rather than acting directly on the cable I would use only that type with aluminium cable.

I did look for picture but most only show the front of the socket.
 
Ahhh, so you could have a good solder joint on the copper plating, but the alu core just eats away.

I like rising clamp connections, but the designs (cosmetically) are somewhat limited and I'd rather not replace all the sockets. Would rather have a clean way of either terminating CCA in a screw point, or converting it to full copper prior to inserting into the accessory. Is there anything wrong with the ferrule approach?

Fubar
 
I have never tried a maintenance free connection with aluminium cable but most the terminals used at the time were this
R7122006-02.jpg
design where the metal wrapped around the cable and the insulator was separate to the terminal.

Even the simple chock block had a small bit of metal between the screw and the wire.

Today the regulations do not allow aluminium of smaller than 16mm² so finding any device which is designed of 4mm² is likely impossible. In 1965 to 1979 everything was over engineered and more able to work with aluminium once the conflict was over we returned to copper cable in fact well before think it was around 1965 to 1970 where we used aluminium cable.

I would say your options are sockets with clamps or a re-wire using modern sockets with the old cables is not really an option. I suppose you could make inserts to distribute the load on the cable but personalty I would just select suitable sockets and plan for re-wire before next decoration.
 
Do the regulations stipulate a proactive changeover of existing CCA during any work then?

Would the ferules not act as said load distributor in this instance, or would it need to be substantially more rigid?

Fubar
 
Huh, did not know that one. What's the reasoning behind the failure? mechanical stress, chemical incompatibility... etc?
Solder is very soft and 'creeps'. A screwed terminal which has been tightened onto solder will therefore very commonly become loose in the fullness (or, sometimes, shortness!) of time.

Kind Regards, John
 
Suggestions in order of preference:

1. Replace the cables
2. Pin crimps as in ericmark's post
3. Butt crimps, connecting the CCA to a short piece of stranded copper of the same size.
 
As a matter of interest, what was the copper cladding of the aluminium meant to achieve - reduced susceptibility to surface corrosion?

Kind Regards, John
 
Copper both protects from surface corrosion, and to a degree will help conductivity disproportionately more due to the skin effect. Although that's a lot more prevalent at high frequency.

Cheers Flame, Is there a particular reason to prefer the pin crimps over ferules?

Fubar
 
Copper both protects from surface corrosion, and to a degree will help conductivity disproportionately more due to the skin effect. Although that's a lot more prevalent at high frequency.
Thanks. It sounds as if protection against surface corrosion was the main idea then. Skin effect at 50Hz is surely so small as to be irrelevant, unless one is talking about truly massive conductors? [ the "skin depth" for aluminium at 50Hz is around 10-12mm ]

Kind Regards, John
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top