Contactor not energising with voltage present.

Question

Hi there. I was called to an oven fault yesterday and found the circuit incorporated a contactor. I had voltage up to contactor but it would not energise and had no voltage leaving to the oven. 
 I changed the contactor thinking it would sort the problem but it made no difference. 
 In the top of the contactor where the supply sits there&rsquo;s an mcb sitting in parallel which appears to feed a fire suppression pump mounted in the extractor hood. My thoughts were that perhaps this could be the issue but I don&rsquo;t know enough about the suppression unit to test it. Anyway I would have still thought the contactor would pick regardless? 
 
 Any ideas would be gratefully received. 
 
 cheers 
 
 Ben

Sparkymark · Accepted Answer

Thanks for posting the photo, that seems to confirm suspicions. It looks like they&rsquo;ve used the brown and blue cores in the flex as the live and neutral supply to the remote device and the &ldquo;earth&rdquo; as the switched live back to trigger the contactor. It seems that whatever the fire suppression device is that&rsquo;s where the issue lies. Without any more info on that it&rsquo;s not possible to know what the problem might be and I suspect you may have to involve someone else who knows more about these unfortunately. If you want to confirm that the contactor is working you could turn off the mcb, remove the live to the flex from the mcb and the earth from the flex from A2, and put a link wire from the mcb to A2. When you turn the mcb on the contactor should trigger. This could only be for a quick check though as it obviously removes the safety interlock so would need to be put back how it was.

Contactor not energising with voltage present.

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