We buy aluminium cable.

Where aluminium earns its place in Houston work

The common applications are predictable. Service entrance cable in SER and SEU constructions, feeder cable in the larger sizes, underground residential distribution in URD, and XHHW-2 singles pulled for services and subpanels. Above 1/0 the case for aluminium becomes hard to argue with on a long run. Below that the metals are close enough that the drawing decides.

Overhead conductor is a separate category. ACSR and its relatives carry distribution circuits on poles and towers, and they arrive as reels of bare stranded aluminium with a steel core. Conductor removed during a rebuild or a reconductoring job is heavy, plentiful and handled differently from insulated cable. The reels are long, awkward and moved with equipment rather than by hand.

Industrial plants use aluminium in tray and conduit feeders as well, particularly where the runs are long and the supports are already loaded. A plant expansion often produces aluminium partials alongside copper ones, and the two are almost never interchangeable in a design. The tray work is a smaller stream, but a steady one.

• SER and SEU service entrance cable
• XHHW-2 and THHN aluminium singles, 8 AWG and larger
• URD and underground feeder constructions
• ACSR and bare overhead conductor on reels
• Feeder cable, three and four conductor with ground

Terminations tell you how the cable was treated

Aluminium fails at the connection before it fails anywhere else. The oxide layer that forms on the surface is a poor conductor, so a proper termination either abrades through it or uses a compound to break it down. A lug that was installed dry on unprepared aluminium will run hot, and the heat leaves marks.

That is what a buyer reads at the end of a removed length. Discolouration at the lug, melted insulation behind a termination, or a conductor crushed oval by an oversized connector all indicate a hard life. Clean, bright metal under a lug that was cut off squarely indicates the opposite, and the rest of the reel usually agrees with it.

Service cable is the exception worth knowing. SER and SEU are usually pulled out intact during a panel change and never carried load at the failed point, so the ends are often in better shape than the age of the cable suggests. Judge the cable, not the building it came out of.

Aluminium and copper terminations should never be made in contact without the correct connector. Mention any mixed-metal hardware you see.

Alloy, construction and contamination

Modern building aluminium is an AA-8000 series alloy, which behaves better under a lug than the older EC grade conductor did. The difference is marked on the cable and it matters when the material is going back into a building rather than into a melt. An older conductor is a different proposition from a modern alloy.

Construction is the next question. Insulated, jacketed, bare, steel reinforced, or with a concentric neutral wrapped over the insulation as URD often has. Each is a different lot, and combining them in one description makes the review slower without making it better. A URD reel with its neutral intact is not a coil of ACSR.

Contamination is the last filter and the most common reason a lot drops in grade. Mud inside a coil, water standing in the interstitial spaces of a stranded conductor, paint, concrete and tar all have to be dealt with. Aluminium corrodes faster than copper in the presence of chlorides, so cable that sat in salt air near the Ship Channel or the bay is inspected closely at the cut.

• Alloy and temper, if the print is readable
• Insulated, jacketed, bare or reinforced
• Concentric neutral present on URD constructions
• Water, mud or salt exposure at the cut ends

Aluminium and copper in the same lot

A yard rack usually holds both, and the two are never valued on the same basis. Aluminium has less metal content for the same volume and it is judged more strictly on condition, so a mixed pallet is separated before anything else happens. The gap is not a judgement about quality.

That separation is not a delay. Listing the aluminium reels by size and construction, and the copper reels separately, gives a clearer picture of the whole lot than a single combined weight. Where the two are physically mixed on one pallet, say so and expect the sorting to be part of the review.

For a plant or a contractor clearing a store room in one pass, the practical approach is to keep aluminium on its own pallet as the material comes off the rack. It costs a few minutes at the rack and saves an hour at the truck. The person sorting is then the person who knows what each reel is.