Discuss rcd not tripping on test in the Electrical Forum area at ElectriciansForums.net

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colshaws

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Hi All
Changed a C.U today, Volex (not my choice but customer supplied it) Dual RCD, one 80A & one 63a. All test results good except on RCD test at socket outlets. on half test all OK, on 5 x test all OK but on 1 X test @ 180 no trip but fine @ 0. Ramp test ok. When tested at RCD with mcb's open they both test out OK. Any ideas please.
 

telectrix

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cheshire/staffordshire
you should test the RCDs at the RCDs , with no loads applied. if they test OK< then fine.
 

stef

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Gosport
Test the RCDs with the load / circuit disconnected. Arw they behaving the same way then?
 
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colshaws

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Grays,Essex
I tested at RCD's with all breakers off and were OK, but why when tested at sockets did they not operate at 1 x and only one 1 side of the cycle, all loads were disconnected
 

baldelectrician

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I would point it out to the client and note it on the cert.

If we supply the unit we would replace faulty items under warranty at no cost to the client.
If the client supplies parts then I charge for labour only and they take the hit on labour if something is faulty
 

stef

Regular EF Member
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576
Location
Gosport
I would point it out to the client and note it on the cert.

If we supply the unit we would replace faulty items under warranty at no cost to the client.
If the client supplies parts then I charge for labour only and they take the hit on labour if something is faulty
Good point. If the customer supplied and insists on the parts that is not down to you. Are the RCDs branded or no-name types?
 
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colshaws

Regular EF Member
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Location
Grays,Essex
Brand new Volex 10 way dual RCD unit out of the box, do you think faulty RCD's and if so why do they work OK when tested at the RCD but not when tested further along the circuit.
 

stef

Regular EF Member
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576
Location
Gosport
Brand new Volex 10 way dual RCD unit out of the box, do you think faulty RCD's and if so why do they work OK when tested at the RCD but not when tested further along the circuit.
Was just a thought. Are thereany inductive loads on the circuit which could influence the test? Strip lights, soft starters, filters etc?
 

rich.250

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Cornwall
Something absorbing test current?? If they trip at Rcd load terminals I'd say all is ok, aslong as the ccts tested out ok.
 
D

dim_bulb

Had a thread on this recently and if tests ok at board then it's not a problem
 

stef

Regular EF Member
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576
Location
Gosport
This is from a non domestic experience: RCD tests failed, I suspected a faulty cable, it went up through a false ceiling, then it was spiraled round the sprinkler pipe (!). Once I re-routed the cable the tests were OK.
 

topquark

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Should be testing RCD with all loads disconnected. If you have any loads attached that may hide capacitive/inductive effects then you won't get valid results.
 
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