"The working current only flows between the black and white of the 2 wire cable. Testing the voltage across the black and white should read 240 volts. Since 60 cycle AC (Alternating Current) changes direction 120 times per second, you can imagine that the black is the return for the white, and the white is the return for the black, 60 times per second for each wire."

I've temporarily tied off a 240 baseboard heater during a Reno and am having some issues with the other heaters and thermostats on the circuit,(breaker tripped and thermostat is not cycling properly), Could the tied off wire with ends wrapped separately be causing the problem as it sounds like the lines were using the heater to transfer current to and from?

Disconnecting two wires to a heater unit should have no effect on any other units or parts of the circuit.