RCDs and insulation resistance tests

[studentspark]

Insulation resistance test..

If you test on the load side of an RCD, with the RCD open., would the test voltage still
Go through the RCD sensitive bits?
Basically which side of the switch is the sensitive stuff on.

As you should not carry out an insulation resistance test through an RCD, but may want to test the whole installation, what ways can this be done.
Thanks[/list]

 

[ericmark]

Some manufactures tell you they can be left in circuit and not all RCD's have any electronics. If you test the line and neutral together then there will be no voltage on the sensitive parts.

I would hope all active parts are on the out going side BS EN 60947-2, BS EN 61008-1 or BS EN 61009-1 may give details, but I would always connect line and neutral together to test or remove from RCD.

Reading this thread on IET website forum it would seem the RCD its self can produce odd readings when measuring between live outputs so rather pointless testing between phases or neutral unless you disconnect.

 

[Adam_151]

but may want to test the whole installation, what ways can this be done.

I can't think of a situation where you would want to apply a IR test between live conductors on a whole installation. This would normally be done on an individual circuit, following work on that circuit.

A global test of live conductors to earth would be normal (as other posters have said) as part of fault finding or an EICR, as eric said an RCD connected to live and neutral would not be influenced by this. If it has an earth reference (as most rcbos do, and some RCDs) then disconnecting the reference and leaving floating will allow the test to be carried out (remember to reconnect afterwards)

 

[PrenticeBoyofDerry]

One way around it would be to close the RCDs, and do your tests by linking across live (but isolated) busbar from supply live. When testing with RCDs in circuit, I IR at 250V.

 

[JohnW2]

One way around it would be to close the RCDs, and do your tests by linking across live (but isolated) busbar from supply live.

I'm not sure I completely understand that - could you perhaps explain in a little more detail?

Kind Regards, John

 

[EFLImpudence]

If you test on the load side of an RCD, with the RCD open., would the test voltage still
Go through the RCD sensitive bits?

Assuming you mean RCCBs and not RCBOs -

You should be able to tell by looking at the wiring diagram on the RCD.
Most, I presume all, have the works on the (normally bottom) load side.

Of course, the RCD may be wired the other way round.

 

[JohnW2]

You should be able to tell by looking at the wiring diagram on the RCD. Most, I presume all, have the works on the (normally bottom) load side. ... Of course, the RCD may be wired the other way round.

Indeed. IIRC, all of those I have taken apart have had the 'switch' on the supply side of the 'works' - so opening the contacts does not disconnect those works from the load side terminals.

Kind Regards, John

 

[PrenticeBoyofDerry]

I'm not sure I completely understand that - could you perhaps explain in a little more detail?

If you Croc clipped link between incoming live and buzbar of live load/loads with RCD open you could test at tails.

 

[JohnW2]

I'm not sure I completely understand that - could you perhaps explain in a little more detail?

If you Croc clipped link between incoming live and buzbar of live load/loads with RCD open you could test at tails.

Sorry, but I still don't really understand (is it just me?). Also, what you've just written appears to contradict your statement I was previously asking you to clarify...

One way around it would be to close the RCDs, and do your tests by linking across live (but isolated) busbar from supply live.

... are you talking about the RCD open or closed?

Kind Regards, John

 

[333rocky333]

I didnt think RCD's as most people call a NON Rcbo had a load and live connection anyway.

And John W i was lost there
Im assuming hes linking Across the Rcd, Therefore open or closed Its Shorted across

 

[JohnW2]

And John W i was lost there
Im assuming hes linking Across the Rcd, Therefore open or closed Its Shorted across

I considered that possible interpretation, but it sounded like the worst of all worlds, since it would surely guarantee that the electronics of the RCD were 'in circuit' during an L-N IR test, regardless of which side of the switching contacts those electronics were! I therefore remain a bit lost.

Kind Regards, John

 

[333rocky333]

I therefore remain a bit lost.

Kind Regards, John

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