whats the conductance of a copper water pipe?

Answer 1

I'm going to assume you mean Thermal conductance, since electricity doesn't mix well with water. The thermal conductivity of a material is equivalent to the quantity of heat that passes in unit time through unit area of a plate or pipe in this case, when its opposite faces are subject to unit temperature gradient.

The thermal conductivity of copper is is 3.94 W/(cm C) or 394 W·m^-1·K^-1.

Thermal conductivity changes with temperature. For copper, it decreases slightly as the temperature rises.

Answer 2

As far as conductivity copper is second only to silver/