THW-A Aluminum Wire

What is THW-A aluminum wire?

THW-A aluminum wire is a single-core wire with an aluminum conductor and black PVC insulation, rated for up to 750 volts and a 70°C conductor temperature under Thai standard TIS 293-2541. The "A" stands for aluminum, which sets it apart from THW wire with a copper conductor. Its most common job is the service drop from the utility pole to the meter, followed by feeders in buildings and factories.

Aluminum vs copper wire

Aluminum conducts less than copper, so you need a larger size to carry the same current. In return, aluminum wire is much lighter and costs less, which makes it the economical choice for long overhead service drops and large feeders. Wiring inside the house is usually copper, because most breaker and outlet terminals are designed for copper.

THW-A size and ampacity chart

Values are from TIS 293-2541 (maximum current in free air). Use them as a starting point: in conduit, in bundles or at high ambient temperature the usable current is lower.

Installation notes

• Run it overhead on insulators or in conduit and raceways in dry locations. Do not bury it directly.
• Use bi-metal lugs or connectors where it meets copper busbars or breakers, to prevent corrosion and hot joints.
• The service size depends on the meter rating and the utility's (MEA/PEA) rules. Have an engineer or electrician size it from the load and run length.

Why buy aluminum wire at OneStockHome

OneStockHome stocks BCC THW-A aluminum wire from 10 to 300 sq.mm in 100 m rolls, with 500 m rolls for 16, 25 and 35 sq.mm. Compare prices across sizes, add electrical wire and other electrical supplies to the same order, and get nationwide delivery.