A worker received a shock when fitting a new water meter to a college hot water system. Investigations revealed that plumbing work done 2yrs earlier had not reconnected the neutral star wire from the hot water system to the main switchboard link, but instead to the copper pipework.

The hot water system was connected with star/delta capacity control (low/high), with 2 series elements per phase, with a total per phase load of 1.5kW, supplied from a 480V symmetrical 3-phase, 4-wire system with phase sequence (a-b-c).

PLease Draw a neatly labelled circuit diagram showing all voltages and fault path