Ally cables

[binky]

Never encountered ally cable in a domestic property before, and to really cheer me up its stranded imperial stuff. So at the moment I'm stuck for cable ratings, anyone got any info???

I'm currently trying apply factors to imperial cable postings that appeared on here some time ago. Please tell me if I'm barking up the wrong tree.

 

[Andy™]

work out equivalent metric size then 7671 tables?

 

[green-hornet]

I do not normally see Ally cables in a house because of the sizing I think the smallest was 16mm to carry between 40 and 70 amps depending on how it was installed.

For conversion try this link

http://www.voltimum.co.uk/files/gb/others/5/200701209767imperialcables.pdf

 

[binky]

Kind of what I am upto now, but its a real pain as I'm not really sure what the cable sizes are. For instance the cooker is on a cable that looks more like 10mm on a 32A MCB, which is probaly fine - its been there a long time!!!

Think I will have to go back tomorrow with measuring stick and double check a few things. Out of interest is there any known differences in installation methods for Ally cables (I assume not) or other snags I should be aware of???

 

[green-hornet]

If you count the number of strands per cable it will indicate the imperial size.

 

[Evans Electric]

Aluminium cables appeared when there was a copper shortage and also used as a cheap alternative to copper. If I remember correctly you have to go up a size for ally cable , lighting was 1.5 sockets 4mm etc. There is a problem with the chemical reaction between dissimlar metals, as with ally and the brass terminals in accessories, they should have been wiped with a paste which was called , I think, Densal Paste. I don't have the current ratings anymore.

Deke

 

[Evans Electric]

I don't think they will be imperial by the way, but as I said , a size bigger like your cooker, instead of 6mm its 10mm . It works fine just have to check for oxidising .

Deke

 

[Andy™]

also, are you sure its ali and not tinned copper?

 

[nemesis]

BS7671 page 105 reg 524.1 and table 52.3 gives the minimum cross-sectional area for aluminium cables as 16mm2.

 

[green-hornet]

BS7671 page 105 reg 524.1 and table 52.3 gives the minimum cross-sectional area for aluminium cables as 16mm2.

Yes thats the new regulations though, we used ally cables years ago on distribution cables but only used 16mm up because of the amperage.

Most cables in houses where tinned copper, and not ally, though because of the shortage of copper some ally cables where installed.

 

[Mr Sworld]

If they are real aluminium cables then I'd recommend they are replaced. For domestic properties they are a right pain! Issues with termination's, oxidation and using the correct paste. (Which, by the way, is really hard to get hold of!)

Even for commercial/industrial work they are a nightmare. I've has a phase blow with no warning on a 3-phase supply wired in Aluminium because oxidation happened.

Re-wire the lot!

 

[binky]

also, are you sure its ali and not tinned copper?

Positive, you can tell by the weight, but just to be confusing it is copper coated.

 

[binky]

If they are real aluminium cables then I'd recommend they are replaced. For domestic properties they are a right pain! Issues with termination's, oxidation and using the correct paste. (Which, by the way, is really hard to get hold of!)Even for commercial/industrial work they are a nightmare. I've has a phase blow with no warning on a 3-phase supply wired in Aluminium because oxidation happened.

Re-wire the lot!

They seem to be in good order, its a 70's ex MOD property, which is basically water tight and dry internally, so I don't think oxidisation is an issue. But could do with some more work Pray

 

[binky]

Just a quick update, have had a word with the client who understands a bit about electrolytic corrosion and is quite happy to re-wire sockets downstairs where some DIYing has broken ring and have mixed materials in contact. Not so sure I need to touch upstairs as this is all ally with no intereference, likewise cooker circuit, but I will see if they want to do the lot whilst property is empty. Fortunately shower and lighting are all copper, downside is that property is concrete - oh joy, but have warned that plastering will be damaged. Makes a nice change to meet responsible landlords.

 

[Andy™]

Makes a nice change to meet responsible landlords.

that is unusual!

 

[Mr Sworld]

Result!