SUMMARY OF THE INVENTION
The object of the present invention is accomplished by providing a heater having a long heating element, the heater comprising:
a) at least one electrical heating cable which comprises a core comprising about 6 percent by weight of nickel and about 94 percent by weight of copper; and
b) a means for supplying electrical current through the electrical heating cable.
When this copper-nickel alloy is incorporated into such a heater cable the benefits of a low resistance heater are obtained along with the benefit of having a low temperature coefficient of resistance. The heater cable material is also malleable. Such a heater can therefore be utilized to heat subterranean intervals of earth to temperatures of 500° C. to 1000° C. utilizing voltages in the range of 400 to 1000 Volts.