© Ductair Electrics Limited. 2013
Every heater is tested to ensure accuracy and electrical safety.
Electrical resistance is measured from live to neutral for all of the stages.
The loading† is then calculated using ohms law, W=V2/R††
† The manufacturers tolerance for sheathed elements is ±7% on loading
†† The resistance of the elements alters slightly between hot and cold, so a correction
factor of 0.98 is applied
Consists of applying 1250V A.C between the termination and the casing and recording
the earth leakage current, expressed in mA.
This should not exceed 1mA per kW.
Consists of applying 500V D.C between the terminations and the casing and recording
the resistance between the live and the earth, expressed in MΩ.
This should be greater than 1MΩ .