Pete asks this question, which concerns testing an electric oven circuit for insulation resistance, and whether there is a limitation that should be put into the Electrical Installation Condition Report (EICR). It has been answered by SELECT (Theme – Regulations and Legislation):
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Question: I’ve recently tested an oven circuit for which I obtained insulation resistance values of 0.45 Mohms between all three conductors.
The oven was switched off at its associated dials and control, but there seems to be some electronics within. There are also neon indicators. The cooker switch has no neon indicator and when this was switched to the OFF’ position, the readings of insulation resistance I obtained were greater than 299 Mohms.
The oven is larger than the average size typical. The client and I tried to move the oven to gain access to the supply terminals, but it caused damage to the flooring and the client was insistent, therefore, that this not be tested.
This is a dilemma as you can appreciate - I may have to issue an unsatisfactory here.
Do I record a limitation for this circuit? Or does this need further investigation? Should I contact the manufacturer for further guidance?
Your thoughts and guidance would much appreciated.
Answer: It is recommended that insulation resistance periodic testing be carried out between live conductors (line(s) and neutral) connected together and earth.
This will avoid the need for disconnection of fixed current using equipment.
This can also be recorded in Section D – ‘Extent and limitations of inspection and testing’.
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