Industry study compares copper with aluminum connectors for power distribution

The International Copper Association has released test results comparing the connectivity of copper and aluminum wiring in electrical wiring applications.
According to the association’s press release, the study found that copper wire with copper connectors is more reliable and outperforms aluminum alloy wiring systems for power distribution applications.
The study compared three types of electrical connections, including copper connectors between copper wires, aluminum dual-rated connectors between copper wires, and aluminum connectors between aluminum alloy wires.
Testing was carried out at the request of the International Copper Association by PowerTech Labs in Surrey, B.C.  in 2013 and 2014. 
Details of the testing were provided by the International Copper Association in a press release on November 14, as follows:
“Mechanical screw type connectors were used to connect lengths of #1 AWG copper wires and #2/0 AWG (8000 series) aluminum alloy wires. These wires are typically used in power distribution applications at voltages less than 1000 volts. The connectors were standard single screw lug connectors obtained from local suppliers. These wire and connector samples were subjected to accelerated ageing by current cycling using the test procedures outlined in IEC 61238-1 as a guide.
The testing included 1500 current cycles applied through the wires and across the connectors. The DC resistance and peak temperature of each sample were measured during the testing. Temperatures in the connections typically climbed from room temperature to 100 degrees Celsius above the ambient.
Additionally, tests were performed with different levels of torque applied to the connector screw, with the screw tightened to 70 percent, 100 percent and 125 percent of the rated torque. Measurements were made with aluminum alloy samples prepared with and without abrasion of the conductor surfaces and with and without oxide inhibitor, as code-required installation instructions for aluminum require surface abrasion and the application of oxide inhibitor. The copper samples were not specially prepared in any manner.
The copper conductors with copper mechanical connectors performed well with no sample failures through 1500 cycles. On the other hand, 100 percent of the aluminum samples torqued to the manufacturer’s specifications failed the test. This result was irrespective of conductor preparation.
The study also found that 33% of the samples with copper conductors and dual rated (aluminum/copper) connectors failed testing to 1500 cycles; and 94% of the dual rated (aluminum/copper) connectors with aluminum wire failed or showed significantly increasing resistance and heat to 1500 cycles.”
The complete Powertech Labs report titled “Connectability Testing of North American and Chinese Copper and Aluminum Wiring” is available from the Copper Development Association (Report # PL-00236-REP1, 27 June 2014). Click here.

To read the ICA press release of November 14, 2014, click here.