EICR aluminium armoured cable

[davesparks]

I'm doing another EICR, I still don't like doing them, and still seem to attract the weird/unusual/uncommon stuff.
This time I'm faced with aluminium armoured cables.

My question is, does anyone have datasheets, or could anyone point me in the right direction for finding information on these cables. I'm specifically looking for anything to help identify the conductor size, CCC, VD and armour CSA/suitability as CPC and/or main bonding.

There are two different types of aluminium armoured cable, my instincts tell me one is older than the other.
The first is a 3core with round solid aluminium cores, each core is insulated with black insulation printed with numbers to identify the cores. I'm not sure what the insulation material is other than being a plastic that doesn't quite feel like a normal PVC insulation.
The armour is aluminium strands with a rectangular ish cross section.
The outer sheath is black shiny plastic much like you find on older SWA, it's embossed with various writing (stupidly I didn't write down the information, I'll do that tomorrow when I'm back there, but I'm pretty sure there wasn't anything specific to identifying the type or size of cable.

The second type of cable is similar, but my instincts tell me it is more modern, this cable has the same appearance to the outer sheath and the same rectangular cross section aluminium armour.
The cores are solid aluminum sectoral (I think that's the right term, they have a wedge shaped cross section) and are insulated with coloured insulation (red, yellow, blue, black) that looks and feels like the insulation you find on older SWA.
Again the outer sheath is embossed but I haven't yet made out any useful information on it.

I'll get some better pictures and post them tomorrow, but these just about show the cores.




And for a bonus question, what do people think about coding aluminium armour terminated in a brass SWA gland with no obvious signs of corrosion?
Also aluminium and copper core terminated together in brass/plated brass terminals?

My initial reaction is C3 for both.

 

[nicebutdim]

You might not like EICRs, but I'm enjoying reading about the oddities you turn up in the course of them.

 

[DPG]

Very clean board and wiring that Dave. Give them extra marks on the report for cleanliness!

Yes I am joking by the way

 

[davesparks]

Very clean board and wiring that Dave. Give them extra marks on the report for cleanliness!

Yes I am joking by the way

I can't really fault them with the aluminium, it's horrible to work with. I had to extend on eof the 4 core cables a couple of years ago and the armour and cores fracture so easily when you bend them it makes you scared to even try and get them neat. It took me a few goes to get the armour strands terminated properly without them all just snapping off as soon as I tried to spread them.

I used a cast resin SWA joint with clamp type connectors specifically suitable for aluminium cores, everything checked as suitable for use with aluminium cables with the manufacturers data.
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You might not like EICRs, but I'm enjoying reading about the oddities you turn up in the course of them.

That's part of the reason I post these questions on here instead of just contacting someone who will know the answer directly, the answers might help someone else too.

 

[Marvo]

The problem with aluminium conductors is that there's different alloys like the 1000 series and 8000 series as well as differently processed like H9 temper. This all affects their physical properties such as how prone they are to creep and fracture and dictates their suitability in different applications and in some cases can affect their current carrying capacity.

The only way you can reliably assess an aluminium cable (AWA) is by identifying it's make and model number and referring to the manufacturers data sheet.

Okay, now we've got the technicalities out of the way, feel free to use the African rule of thumb method which is max current is roughly equal to 4.5 times the CSA.

The problem with using a brass SWA gland on an AWA cable is fracturing of the armour strands because of the angle their clamped at in the clamping ring. If you can remove the tape enought to inspect it without disturbing the cable in doing so and there's no signs of fracturing and no signs of corrosion I'd probably give it the benefit of the doubt. Just carefully retape it afterwards and then give it a wide berth. I'd be very careful not to move anything and deffo don't be tempted to give it a tighten with a spanner.

 

[Let me think]

And for a bonus question, what do people think about coding aluminium armour terminated in a brass SWA gland with no obvious signs of corrosion?
Also aluminium and copper core terminated together in brass/plated brass terminals?

My initial reaction is C3 for both.

Depends on environment, however as you've stated no signs of corrosion, then agree with C3 as still a risk over time, albeit low.

 

[davesparks]

Further details from today's poking and prodding/detailed technical inspection.

Cable one, the three core, has a weird rubbery layer/bedding between the armour and the sheath and between armour and cores, the best way I can describe it is that it feels like a self amalgamating tape, but is part of the cable structure.
The embossing on the outside of the sheath reads PIRELLI GENERAL ELECTRIC CABLE (M) 600/1000V 1972

cable 2 does not have any rubbery layer, the embossing on the sheath reads E-S.C.P. ELECTRIC CABLE (M) 600/1000V

 

[Marvo]

When I first saw the thread I thought they may have been an MV cable being used in an LV application but your info has now ruled that out.

If they were manufactured in the late 60's/early 70's I wouldn't get too hung up on the look and feel of the insulation if they've both still got good electrical integrity, back then they were still playing aroung with different cocktails of plasticisers and additives so inconsistancies wouldn't be surprising.

Is the weight of the cable hanging on the armour strands at the gland or is the cable firmly saddled to the wall below the gland? If it's hanging I'd be very worried about the armour strands breaking and I wouldn't be doing too much 'prodding and poking'. I'm not very familiar with the UK failure code definitions but I'd definately state this as an advisory of some sort, it might be fine for years but it's reasonable to assume imminent failure the minute there's any kind of disturbance such as additional installation or alterations in the local area.

 

[Mark42]

Interesting stuff. Thanks for posting. Does aluminium-cored armoured cable have aluminium armour too? That would be pretty useless. Excuse my ignorance but I have a possible Ali cable sub main task coming up, but I’ve never used it before!

 

[davesparks]

Interesting stuff. Thanks for posting. Does aluminium-cored armoured cable have aluminium armour too? That would be pretty useless. Excuse my ignorance but I have a possible Ali cable sub main task coming up, but I’ve never used it before!

In this case yes it does have aluminium armour, and it obviously dates back to the copper shortage when aluminium was used a lot more.

These days I don't think you can even get aluminum armoured in these smaller sizes.

Why do you think aluminium armour would be useless? single core armoured cable normal has AWA instead of SWA because of the eddy current issue with steel.

 

[davesparks]

Thankyou to those who have contributed, it has been helpful.
Unfortunately I am still at a bit of a loss as to current ratings and suchlike.

Maybe the fountain of all knowledge @Lucien Nunes could help?
[automerge]1596369768[/automerge]
He'd probably enjoy a rummage around this particular site, it's an electronics company with some interesting vintage gear in storage.

Without looking too hard I saw 3 avo model 8's, a master compass, a new in box metalclad kantark fuseboard, an evershed and vignoles ducter, stacks of old components like valves just laying around,

 

[timbobelfast]

Thankyou to those who have contributed, it has been helpful.
Unfortunately I am still at a bit of a loss as to current ratings and suchlike.

Maybe the fountain of all knowledge @Lucien Nunes could help?
[automerge]1596369768[/automerge]
He'd probably enjoy a rummage around this particular site, it's an electronics company with some interesting vintage gear in storage.

Without looking too hard I saw 3 avo model 8's, a master compass, a new in box metalclad kantark fuseboard, an evershed and vignoles ducter, stacks of old components like valves just laying around,

The small ALU round conductor cable will almost certainly be 16mm.

There are some ALU tables in BS7671 that may help, but indeed you need to know the exact cable characteristics.

The site I am working on presently has a lot of SWA ALU cables, most installed circa 1970s.
I have the old original site cable schedule which shows cable size and I think CCC of the runs.

Most of these cables are Pirelli such as the ones you have discovered.

There is also some information in the Commentary on BS7671 book, which may be of use.

I will see what I can dig out for you.

If you have any design software you could always draft up a couple of cable runs in ALU to see what that throws up, but this is over and and above what an EICR is all about!

 

[davesparks]

I know it's not what an EICR is normally about, but if I don't get the information it's an FI code.
And the person doing the further investigation will be me, and it's a payment in kind job so I'm getting the same return whatever.