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Hi guys
I've recently competed an installation on a large domestic property

I've now found that one of the Rcds is tripping every 2 or 3 days
I've isolated a ring main circuit and the rcd is fine.
I've carried out insulation test on circuit L-N L-E N-e all clear
But when I test between cpc of the disconnected circuit and neutral bar at cu I get a reading of 4-5MOhm on both outgoing legs
I've split the ring into to 2 radials,but still get this reading on both halves
I've also got 50V between disconnected earth and neutral bar
Any ideas guys
Cheers brian
 

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RIP 1959-2015
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39,618 Posts
Hi guys
I've recently competed an installation on a large domestic property

I've now found that one of the Rcds is tripping every 2 or 3 days
I've isolated a ring main circuit and the rcd is fine.
I've carried out insulation test on circuit L-N L-E N-e all clear
But when I test between cpc of the disconnected circuit and neutral bar at cu I get a reading of 4-5MOhm on both outgoing legs
I've split the ring into to 2 radials,but still get this reading on both halves
I've also got 50V between disconnected earth and neutral bar
Any ideas guys
Cheers brian
Hello Brian,Welcome aboard.:thumbup:

You could be picking up phantom voltage,so you should get a low z meter.



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Having an RCD tester that measures the trip current can really help in these situations. You can use it to check the current that it takes to trip the RCD with sections of the downstream circuit disconnected until you have isolated the section that is making the greatest contribution to the leakage current. From there its just good old-fashioned fault-finding.
 

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rollin' with doube d's
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102 Posts
Hi guys
I've recently competed an installation on a large domestic property

I've now found that one of the Rcds is tripping every 2 or 3 days
I've isolated a ring main circuit and the rcd is fine.
I've carried out insulation test on circuit L-N L-E N-e all clear
But when I test between cpc of the disconnected circuit and neutral bar at cu I get a reading of 4-5MOhm on both outgoing legs
I've split the ring into to 2 radials,but still get this reading on both halves
I've also got 50V between disconnected earth and neutral bar
Any ideas guys
Cheers brian
50v is probably ghost / inducted voltage.

RCD trip probably faulty appliance with a something on a timer, whats on the circuit?

Fridges/Freezers with cyclic defrosters can cause this behavior.
 
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