Using Of Aluminum Cable Instead Of Copper In Low Voltage System

Connecting aluminium conductors is much more tricky than working with usual copper conductors. The main reason is because in air Al is immediately covered by a very thin layer of oxyde which increases contact resistance. There are procedures to follow (which include chemicals) and the connections must be specifically approved for aluminium.

Where I live aluminium is nearly never used for low voltage (excepted for some very large power distribution cables), even if copper is now very expensive. Also Al is only an option for higher section conductors, small ones don't exist in Al as they'd be too fragile.

There are tables which you can use for comparisons, best is to check good manufacturer documentation, not Wiki or books.

Pay also attention to the mechanical strength differences which are important for short-circuit computations. Thermal expansion are different too as well are melting points.

I for one have never found aluminium to be tricky to work with. The fundamental difference to bear in mind is that it is not copper and copper techniques are not applicable on aluminium cores.

I agree, ali instantly oxidises, once cleaned. Therefore using the conductive paste prevents the electrical resistance at any lug or ferrule.

Crimping lugs and ferrules is different and hex crimps are unsuitable on ali, where hex crimps are most suitable for copper cores.

Copper is a solid metal and cyclic heating will not allow the core to slip from the crimp, however, as ali is not a solid, but has flow characteristics, (the more one squeezes ali the more it flows away from the compression point and becomes loose over a short period of time, with or without cyclic heating).

There is a set pattern when crimping ali lugs and ferrules, and this is easily followed, top-to-bottom crimping, otherwise one will extend the lug or ferrule and create an air void which then produces arcing, ozone, and finally failure due to a hot spot.

Nothing wrong with using bimetallic lugs and ferrules for bus connections or connecting to other copper cores.

Don't try to solder on ali, you will inevitably end up with a dry joint which will fail very quickly.

Ali is perfectly suited for low voltage applications, if the person working with it knows how to work with it. There are few similarities when working with ali, as opposed to copper, don't try and mix techniques or applications.

Ali is used for lightning protection applications in many countries due to cost, lightness and ease of installations. Aerial bundle is normally ali and used extensively in Ireland, S Africa, Zambia, Botswana, Europe, Au, NZ and many more countries for distribution systems and without troubles.

Just don't apply copper techniques to ali. They are different.

The reason ali is limited on HV cables is due to manufacturing lines, a 2500mm2 Cu cable is a max size for cable production. To have an equivalent size in ali would be a 3500mm2 cable, causing increase of insulation, thicker cables and changing the manufacturing line which is not practical or cost efficient, so limitations in processing is the reason for limited ali cable sizes, and a low demand in the market for large ali cables which don't fit industry sized ducts, joint bays, lugs, ferrules, pulling equipment, road trailers etc., is not practical.

So before terminating, jointing ali cables, make sure you have the right tooling and correct knowledge to work with these cables. It is easy when you understand what you are working with, so don't sweat it, go learn.

Your local electrical code should specify the allowable current ratings for aluminum conductors in various configurations. The conductors will be somewhat larger than copper ones. Voltage drop calculations use the same formulas as for copper, but with a higher resistivity value for aluminum.

Of even greater concern are methods for wire termination, to avoid oxidation and to accommodate thermal expansion/contraction. Hardware must be certified for use with aluminum.

Aluminum conductors were the "hot" item when I first got out of college. The engineering firm I worked for spec'd a lot of them on construction jobs. Forty plus years later, the use of aluminum is rare, and for good reasons. Even following all the guide lines for connecting them to panels with copper buses the corrosion issue still can become a dangerous problem. Many over heated terminations later, the use of aluminum is now a "hot" item, but not for the same reason. The next time I see aluminum allowed as a conductor on a process skid, it will be the first time in 25 years of this type of work.

Tornado has spelled out your biggest concern when using aluminum wire.

"to accommodate thermal expansion/contraction"

The expansion and contraction causes loose connections over the years, and has been the cause of many fires. Aluminum wire is no longer allowed in many, if not all US States for residential building.

Even with "listed" connectors, my experience is check and tighten all connections once a quarter.

it'll be fine

Ah the Nixon years, with the electrification of China his shining star. The copper went there while aluminum wired "Manufactured Homes" burned, starting at the water heater and working its way back.

I happened to be on the roof of a building with overhead aluminum feeders exposed to the exhaust from a cooling tower when they failed.

Don't, there are many very good reasons why virtually all low voltage cabling world wide is copper and not aluminium.

Before even considering aluminium cables check your local standards to see if it is even legal, then stick with copper. Aluminium cables should only be used in the most specific of applications.

GA.

My experience with AL wiring in houses is you cannot get a decent connection. With screws the AL flows, when you pull a receptacle to replace it you usually find hot connections, or the wire breaks at the connection or worse, at the back of the box. It is not forgiving when handled "too" much.

The 4/0 or heavier on the supply side just does not get the handling, and the strength with the large size is usually not an issue.

same here.

For transformer tails aluminium is great. We always used 4 sector solidAl insulated and sheathed singles. Due to its rigidity it can be dressed to make a neat job. Although one of our genius engineers ordered 960mm² instead of 600mm². I'd rather bend scaffold poles.

One of our plants was built in the mid 1960's using mainly Al cable, we had nothing but trouble with terminations burning off. Which I finally tracked down to one of our electricians checking motor terminals during each plant shut down. He'd give each connection a tweak eventually compressing the lugs to the point they burnt off.

After reading all the pros & cons of using AL cables, I feel that some research is required to meet alternative to copper which getting expensive day by day. Many copper mines will dry out of copper and there will be no substitute. May be AL cables are modified to solve the problems as reported by other fellow engineers and AL is used widely in the industry.

There has been over 50 years of research done on ali cables. The copper price has fallen a lot and the only expense on cables is the insulation materials which is derived from petroleum products, so what are you going to research?

Ali conductor has a good service record world wide. And don't worry about copper, there is more than you realise, available. It is manipulated by suppliers to maintain high prices, research economics before you waste time reinventing the wheel.

There is more than enough trees to produce insulation for cables.

Trees to make insulation?

Are you talking about paper-wrapped wires? Those things are a nightmare, even worse than the old cloth-wrapped 'romex' cables. Here in Chicago we run all the house wiring in metal pipe, so when that cloth/paper insulation fails (and it WILL, sooner than you think), it's an immediate short to Earth Ground and a tripped breaker/blown fuse. I can only imagine what it would be like using that stuff in areas with more lax electrical codes.

Wait, I don't need to imagine, a post somewhere above this already showed the result: a house merrily burning away.

Cables my dear fellow, not piddly house wires. That they can use XLPE, PVC, neoprene, rubber, EPR etc. Cables

RSA used steel conduits and then changed to PVC conduits in houses, buried into the brick work then plastered over. Steel still used in industrial applications.

And yes, trees make great insulation so there is a bountiful supply of trees for cable insulation.

Another freely available insulation is water, and it works very well in HV DC converter stations at 600kV DC and on blast furnace electrode cables.

Conclusion: Al cables can be used at the place of copper but with greater in size and its lugs should be crimped time by time because the conductor inside the lug gets loose time by time.

Thanks for nice inputs. Every time gets nice answers from here.

Never re-crimp an ali lug or ferrule after a time period. Sure fire way to have corona, hair line fractures, cracking and termination/connection failures. Only re-torque the bolts when doing regular maintenance.

If you have used the correct die set, the correct crimp for ali, it will not flow easily nor pull out. Hence I stated, do not hex crimp ali ferrules or lugs. Hex is copper only.

Not exactly, if using round copper cord you may use hexagonal crimped connectors specifically designed for that type and size of conductor and using the approved dice set.

Both "sector"-form and round aluminium conductors can be found but as several mentioned it before they require specific connections and special manufacturer instructions must be followed. It's more critical than with copper as errors can have more easily dramatic consequences.

Sorry my friend, the word is 'Exactly'. We are talking cables and nor chords.

Hex is copper and cannot/should not, be used on ali, which was clearly stated.

Ali is only indent dies.

Fine stranded welding type cable is bathtub indent and that is copper flexible.

Sector shape ali is indent,

Sector shaped copper is hex.

The only specific with ali is to follow the crimping sequence, which can be related to the procedure one used to tighten the wheel nuts on the wheel. (I. 3. 2. 4 or 1, 3, 5, 2, 4.) Ali flows away from the crimped area, when crimping.

If you crimp a mid span joint, (Al) with the wrong procedure you will end up with a banana shaped ferrule.

If using compacted cor, .i.e. 120mm2, use a 95mm2 lug or ferrule and not a 120mm2 as it will not crimp to the desired compaction. So always check if you are using thick walled barrels on a lug of ferrule or a thin walled barrel. It makes a huge difference to the connection point and current carrying capabilities of the cable. The wrong termination lug sets the ampacity of the cable and not vice versa.

Don't mix cables and chords, chords and terminated with terminals or chocolate blocks (10MC Strips).

I must check the exact English translation, here I mainly use the German terminology. I possibly used the wrong term, sorry. Will check the documentations.

Lugs come in various manufacturer as well as international standards, it depends not only on the mm2 but also on the construction of the conductor (there are standardized classes according to flexibility of the conductor).

Dices must be approved for the used cable termination.

For lugs above 4 mm2 I always request hexagonal crimping, never asymetric crimping which causes irregular crimps which are often not even so-called "gas tight" (you can see it id you cut a sample).

I have "negated" the unfriendly "Off Topic" someone gave you, probably the person you "corrected".....that happens on CR4, its unfair, but sadly quite normal for some anonymous dim wits here!!

You learn to simply ignore them as they "bring nothing to the table except their appetite!"

So you are now back to Zero....

Have a great day....

Thanks. It happens that I've some problems with the English terms (for electrotechnical stuff German is the best and most precise language). Also North American and continental European practices widely differ.

Many moons ago when I worked for AMP we found that tin-plated Al romex actually worked well (at least in our tests). Also, the big power guys have a dressing for aluminum connections. It has powdered nickel that apparently breaks through the oxide layer.

Its neat stuff - feels gritty.

Wasn't there a method of connecting Copper lugs to Ali cables using friction? Is that still used?

Nobody here, even those who appear to have real/actual Ali knowledge, have mentioned it.

My only experience is with car starter motors using Ali windings....a long time ago! Are they still made like that?

We commonly supply Aluminium to copper bimetal joints that are friction welded (that's aluminium one side copper the other) and designed to connect aluminium cable up to copper cable. Really impressive joint. I have not come across friction welding directly to the cable however because the friction welding machines are hardly cheap or portable.

AMP has (last I heard) a crimp connector for Al solid wire. Talk to them.

Check products from companies like for example Klauke or Weitkowitz, they manufacture special crimp products for Al conductors. Especially it's extremely important to follow strictly the recommendations of the manufacturers (rather than some generic documentations or even standards). If doing so Al connection work well though they require more care than Cu connections.

That said, it must be carefully checked if it's really worth using Al conductors in low voltage. I can mainly remember some very large busbars in a few large distributions as well as high section sector as well as round conductors for cables. Rather than playing with Al I'd rather try to reduce the distance to the distribution transformer where possible.

Alice in Wonderland and Humpty Dumpty seem to be duking it out here, neither of them knowledgeable.

Oh shame, are you feeling left out my Precious?