\$\begingroup\$

Please visit our website for more information on this topic.

Aluminum is marvelous, underrated stuff

And North American AC electrical wiring has achieved mastery of using it, including the unfortunate exception which proves the rule.

Never mind copper being twice the weight for the same ampacity. It's 10 times the cost for the same ampacity!

Copper had to come first, because it exists primordially - you can find copper nuggets in nature, so it was one of the first worked metals in human history. The affordable process for refining aluminum requires staggering amounts of electricity, so by definition, aluminum enters a world that is already fully built-out in copper.

What are the tricks to working with it?

In practical application in house wiring, there are two "golden rules" called out on the first page of the Code book.

Use terminals designed and rated for aluminum wire (NEC 110.3). Generally, the simplest way to do this is to use a lug terminal which is itself made of aluminum. Panel neutral bars, large lugs, Alumiconn and Polaris style connectors all use this method.

This works because aluminum has a different coefficient of expansion than copper. When the aluminum lug envelops a copper wire, this thermal expansion works favorably.

The exception that proves the rule is the 1970s experiment with small aluminum branch circuit wires in North America. This was done in response to a copper shortage, and the government ordered the certification agency (UL) to fast-track approval of switches, receptacles and splices. UL hastily certified ordinary devices made of brass without adequate testing. This caused frequent failure, and the postmortem revealed the rule I state above. Design standards were significantly revised (to CO-ALR), and those devices have terminals made of indium, a soft, conformant metal that mates well with aluminum.

Torque terminals to spec with a torque wrench (NEC 110.14). This was a universal "best practice" that electricians did on large high-current terminals, and those have proven reliable in both metals. However, for "the small stuff" (15-50A wires), no one bothered - they just cranked them down "gud-n-tite" with no particular standard for what that means.

And totally unrelated to aluminum, this was found to be a major cause of failure for copper connections, and of course there's no reason to think mistorqued aluminum connections were performing any better. This was coupled with some trade-show testing that proved pro electricians couldn't set torques "by feel" any better than their spouses. It turns out the entire industry had been in the bottom quartile of the Dunning-Kruger curve, and many are still in denial.

Use the proper alloy. The 1970s effort involved taking AA-1350 alloy "outdoor transmission line" wire and shrinking it down. This did not perform well. A new AA-8000 alloy was specially developed for interior electrical wire.

So with those application techniques mastered, aluminum is proving to be a winner for architectural electrical distribution. It has always dominated the skies of utility distribution.

That said, in residential the stigma of the 1970s mistake lingers, and don't wire with aluminum smaller than 50A if you want to get good money when you sell the house.

How do you design for aluminum?

A worthy question. And please - if you are designing an EVSE, accommodate aluminum wire. Almost none do, and it greatly increases installation cost (6 AWG copper NM vs 6 AWG aluminum SER/SEU).

The gold standard in the electrical industry is an aluminum-bodied lug connector. So have a copper lead or bar come out of your machine and land on an aluminum bodied lug with two screw terminals - one for your copper lead/bar, and one for the customer supplied wire connection. Torque your side to spec and have a label reminding the installer to do the same. It also helps to use 75C thermal connections, which allows a smaller wire size to be used.

If you are attaching these lugs to a PCB or plastic molding, they do not need to be insulated and can be quite inexpensive.

Reason for no: Tokamaks

If you're trying to run a cyclotron or magnetic isotopic separator, you need the maximum possible magnetic flux in the least possible space. This can be important for motors, too, if you need to cram an extremely high power motor in the limited space between railroad rails, for instance.

For that, copper can't be beat.

If you want to learn more, please visit our website Mingda.

Additional reading:
LABDIP 10Pcs Type A 3 Row 19Pin HDMI-Compatible ...
How to Choose the Perfect OHIO GS Engraving Stylus?
How Does a Hybrid Car Function?
How to Properly Install a Bathroom Exhaust Fan
The Advantages of Utilizing OHIO GS Engraving Stylus
10 Questions You Should Know about Electric Vehicle Charging Stations
The Advantages of Utilizing OHIO Diamond Styli

Reason for no: you want to sell your house.

NEC has no quarrel with use of aluminum wire for small branch circuits, subject to the new rules.

However, if you do, the buyer's inspector will find it, mistake it for the problematic old stuff, and tell the buyer not to buy your house. They will demand a discount, remediation, or walk away.

Use for >50A circuits continues to be perfectly fine. A few superstitious jurisdictions raise that standard to 90A.

Reason for no: flexible cordage

For fine-threaded flexible cordage such as found between an appliance and its wall plug, aluminum is really too brittle. It does not like the constant flexure.

Reason for no: physical working

Aluminum has no fatigue limit so if it's in an application where it'll be carrying a lot of physical weight and moving a lot, such as an overhead line, it's going to accumulate metal fatigue and fail. Copper has the same problem, though.

The cure for this is ACSR, which is aluminum wire around a steel core. Now the steel core takes care of the physical strain of supporting the cable, and the aluminum is just along for the ride. This is not used in residential "service drops"; that's just regular duplex/triplex/quadplex.

Blog

later post  |  index  |  earlier post

Why is aluminium environmentally friendly?

  Tuesday, 2 March 2021

Known as the green metal, aluminium is one of the most environmentally friendly metals because of its sustainability. As the most recyclable industrial material, aluminium can be recycled infinitely to produce the same product. Recycling aluminium also saves 95% of the energy used in its production from raw materials.

Not only does recycling aluminium reduce its environmental impact, but the metal’s properties mean that it can often be used to replace more environmentally harmful materials. In construction, aluminium is used 74% of the time in place of timber during the development of residential properties, reducing deforestation. Aluminium also requires less maintenance compared to timber.

As aluminium is particularly easy to handle, the environmental impact is further reduced when it’s used in construction as transportation costs are reduced.

Recycling aluminium facts

• Recycling aluminium saves 97% of greenhouse gases used in the primary production process
• One tonne of recycled aluminium saves nine tonnes of CO2 emissions and four tonnes of bauxite (the raw material that aluminium is made from). Nine tonnes of CO2 is the equivalent of driving 25,200 miles
• Recycling one aluminium can saves enough energy to run a TV for around 3 hours
• One tonne of recycled aluminium saves 14,000 kWh of electricity, 1,663 gallons of oil and 10 cubic yards of landfill space
• Aluminium takes 200-500 years to fully breakdown in a landfill site

How is aluminium used in construction?

Aluminium is the most frequently used metal in the world as it is extremely versatile, lightweight, and durable. Buildings constructed using aluminium in place of other materials like titanium are not only robust but also recyclable and environmentally sustainable.

Aluminium alloys are used in many applications where strength and durability are needed simultaneously, for example in the construction of planes, vehicles and even skyscrapers.

Working with aluminium enables architects to be more creative with their designs because of its flexibility. Aluminium is also a suitable metal for building window frames as it can be rolled or hammered into extremely thin sheets without breaking. Another benefit to using aluminium for window frames during construction is the added thermal efficiency it provides, which again helps to make buildings more environmentally friendly.

Get in touch today

Give ASM Metal Recycling a call to learn more about how we recycle aluminium and to get the best aluminium scrap prices. Find your local depot here, or check out our scrap metal collection services.

later post  |  index  |  earlier post

For more information, please visit Aluminium Alloy Cable.