Ohm's Heating OS Alu-18 is an aluminium-jacketed constant-wattage heating cable rated 18 W/m with a total output of 1600 W over an 89 m length at 230 V. The aluminium sheath conducts heat efficiently to the surrounding material and mechanically protects the heating element. Typical use is in-screed floor heating and larger snow-melt installations designed to the specified linear output.