3 phase heating elements
They are connected in delta


That's a 22 ohm resistor connected to each line voltage. 


  I measured between L1 and L2 etc with the rest all disconnected. These are approximately 6000mm long and running 415v delta


The power for each 22 ohm resistor is \$V_{LINE}^2/R\$. This equals 7.828 kW.

The total power is therefore 3 x 7.828 kW = 23.485 kW