ECN Forum Forums General Topics of the Trade General Discussion Area 3 Phase Panel feeding single pahase lighting

We are temporarily feeding a 3 phase panel with 10 awg wire to power some lighting circuits. This is a temorary lighting solution for some offices while under reno. All lighting circuits will be single phase. Obviously the 10 awg can feed maximum 30 AMPS...but would you calculate (estimate)the total wattage for lighting allowed based on 3 phase P=E*I*1.73 or single phase P=E*I?