I need to wire an electric water heater that consumes 3kW of power and I am trying to figure out appropriate size of flexible multi-strand pvc insulated copper cable. I understand that if the input voltage is 200V, current flowing through the cable will be 3000/200 = 15A.
Now, as per the attached current capacity guide of the cable manufacturer, I should use 2.5 sq mm thick cable, which is rated to carry 18A. So far so good, I think.
What I am confused about is the column header that says "Current carrying capacity # of 2 wires, Single Phase". What do they mean by "2 wires"? Does that mean the current capacity of one cable is only 9A?
I checked a couple of other cable manufactures' rating sheets as well and they say the same thing.