At room temperature, the electrical resistivity of constantan wire is approximately 52 micro-ohms per centimeter. At 20 degrees Celsius, the resistivity is 49 micro-ohms per centimeter. Constantan wire alloy is made from 55 percent copper and 45 percent nickel.
Constantan wire has a density of 8.9 grams per cubic centimeter. This wire also has a melting temperature that ranges from 1225 to 1300 degrees Celsius. Constantan wire can be soldered and is ductile.
The resistance of this wire alloy does not change when there are small changes of temperature. For this reason, constantan wire is used for thermocouples, DC current shunts and power resistors.
Although the use of solid constantan wire can be handled without any hazards, Inhaling dust or fumes produced by either grinding or welding this product can be dangerous. Inhalation of this substance can cause breathing problems that may require medical attention.