One of the most often copper wires used in buildings and in commercial areas is the 350 MCM XHHW-2 copper conductor building wire. This wire is a particularly good choice for applications needing a 350 gauge wire for several reasons. First, as an XHHW wire, it features a specific type of insulation that protects the wire from heat, water, and abrasions. Second, as a copper wire, it requires less insulation than other types of wire such as aluminum. It also doesn’t tend to oxidize as much when it’s exposed to air, and even when it does, it can still transmit a current. Copper also carries more current than other materials.

350 MCM XHHW-2 copper wire meets, and in many cases exceeds, a number of regulations and standards. These standards include Federal Specification A-A-59544, UL Standard 44, ICEA S-95-658 (NEMA WC 70), and all of the requirements outlined in the National Electrical Code.


350 MCM XHHW-2 wiring makes use of annealed copper conductors. As indicated by the X in the abbreviation XHHW, this wire makes use of cross-linked polyethylene for insulation. This type of insulation makes the wire very resistant to flames/heat, water/moisture, high pressure, and abrasions. This means that the wire can be used in a wide variety of projects and in a number of different locations.

The 350 size of XHHW-2 wiring is 350 kcmil in size. It features 37 different strands in the conductor. The special insulation is 65 mils thick, and the nominal O.D. is 794. The wire is fairly heavy, with a 1,000 foot spool weighing around 1155 pounds.

This wire is rated for use at three different temperatures. When the temperature is 60 degrees Celsius, it’s rated for 260 amps. At 75 degrees, the amp allowance is 310 amps. Finally, at 90 degree Celsius, this wire is rated for a maximum of 350 amps.


Because of its versatility, the 350 MCM XHHW-2 copper wire can be used in many different ways. The National Electrical Code lists all of these ways, including its use in conduits as service, feeder, and branch circuit wiring.

Because of its insulation, the 350 MCM XHHW-2 wiring can be used in any area, including completely dry, slightly damp, or frequently wet locations. No matter where the wire is used, however, it should not be in any location where the average temperature or frequent high temperatures are greater than 90 degrees Celsius. The wire should also not be used in any application where the voltage will exceed 600 volts. Doing so will damage the wire and may start an electrical fire.

This wire is often used in buildings due to the fact that the flame-retardant insulation can prevent the spread of fires by containing any electrical fires inside the insulation jacket. The fact that the wire can be used in areas where standing water is a concern also makes it a good fit for residential and commercial buildings with basements or in locations that may see frequent flooding.

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