rcd low insulation resistance

[Guest154]

do rcds give low readings when testing insulation resistance

 

[trev]

Why are you testing IR through an RCD?

 

[somersetsparks]

If they have a white fly lead which you have'nt disconnected, or if you are testing L-N with it closed

 

[eckersecker]

I once blew one up so always disconnect line and neutral just in case.

 

[adlermark321]

If you are doing an IR... RCD should not trip as there is no power on the circuit.

 

[Guest154]

testing 17th board 2 rcds , testing whole installation , fly lead between 2 N bars ,power off testing between line- neutral only getting 2.4Mohms , test every circuit individually comes up over 299Mohms

 

[Toonlad]

your doing a global ir test. You have not linked your live and neutrals together then test between them and earth.

 

[telectrix]

remove fly lead from neutral bars. test from L busbar 1 to N 1 with breakers on, RCD off. repeat for L2 busbar and N2. as this is a L-N test, all loads will need removing proir to testing.

 

[Guest154]

cheers

 

[Guest154]

but my question still stands do rcds give off bad readings

 

[SirKit Breaker]

An RCD will always give a low reading if you go across L&N, think about its internal workings and you will realise why.

 

[Jay Sparks]

If they have a white fly lead which you have'nt disconnected, or if you are testing L-N with it closed

Sorry to be picky but a "white fly lead" is only found on RCBO's, not RCD's.

 

[ackbarthestar]

Sorry to be picky but a "white fly lead" is only found on RCBO's, not RCD's.

I've got a couple of MEM 61008 RCDs, both have fly leads.....

 

[markc123]

I've got a couple of MEM 61008 RCDs, both have fly leads.....

They're the electronic RCD's though aren't they which aren't very common.

Most RCD's don't have fly-leads...i've only ever known some of the MEM ones to have fly leads.

 

[ackbarthestar]

Agreed, I haven't seen many for the 61008 RCDs with earth reference fly leads.

 

[somersetsparks]

Agreed, I haven't seen many for the 61008 RCDs with earth reference fly leads.

The company I worked for found from maintenance stats that these MEM rcds were the most likely to fail out of all the 61008 style rcds, what benefit do electronic RCDS give?

 

[T&Earth]

Hi Tel

I thought the white fly lead is connected in with the circuit's CPC.

Cheerss
T&E

remove fly lead from neutral bars. test from L busbar 1 to N 1 with breakers on, RCD off. repeat for L2 busbar and N2. as this is a L-N test, all loads will need removing proir to testing.