Rick If the wiring were to add a good deal of resistance, you would get LESS current through the load and therefore have less power used by the heater, not more. P=V squared/R. The larger R is, the smaller the power consumption. Total power used by the load would be less than 240 watts. But, these connections will add negligible resistance in reality, so figure 240 watts used.
Use 18 AWG or larger wire for connections. 16 AWG wire crimps alot better in those Flexwatt connectors.