A-102-1 Electric Duct Heater Brochure - Brasch

How to Calculate Line CurrentsTo determine the line current use the following formulaeSingle PhaseLINE CURRENT (I L ) in amperes =WATTAGEVOLTAGE1øVoltage{(I L ) Line CurrentThree PhaseLINE CURRENT (I L ) in amperes =WATTAGEVOLTAGE X 1.73NOTE: This is the current which will flow in each of the three lines, regardless of whether the elements are wye or delta connected.(I L ){ {Voltage Delta3ø3øVoltage(I L )WyeSUPPLY WIRE AND LINE TERMINALS SIZING—UL requires thatthe line terminals in duct heaters be sized to accept conductorswhich are rated to carry at least 125% of heater line current. Heatersare provided with properly sized terminals at no extra charge. Fieldsupply wires must be sized to carry at least 125% of heater line currentexcept when the heater is for space heating, is over 50KW andnot more than 3 wires in the conduit—may be sized at 100% ofheater line current.Supply conductors must have insulation rated atleast 75° C (167° F).BULLETIN A102-119