DoorKing 9402 Loop Wire Rolls Available in Blue, Black and Red - 500 & 1,000 Ft. Rolls  18 AWG  XLPE Insulation Loop detectors & loops are strongly recommended on all automated vehicular gate applications to help prevent gates from closing on vehicles in the path of the gate. DoorKing has available pre-fabricated loops, loop wire, loop test meters and concrete and asphalt sealant. Specifications. Wire Gauge 18 AGW Insulation / Jacket Material XLPE