RCD Test Failing

[deejay]

RCD test failing on a single outdoor double socket radial circuit (55.8ms on X5). All other tests ok (IR, R1+R2, ZS). Functional test of RCBO ok. Tried circuit on another RCBO and test still fails so not the RCBO.

Am I missing something obvious? Thanks

 

[James]

Is there something in the installation that may be injecting dc into the supply?

 

[Pretty Mouth]

RCD test failing on a single outdoor double socket radial circuit (55.8ms on X5). All other tests ok (IR, R1+R2, ZS). Functional test of RCBO ok. Tried circuit on another RCBO and test still fails so not the RCBO.

Am I missing something obvious? Thanks

Have you tried testing with the circuit conductors disconnected from the RCBO?

 

[deejay]

Have you tried testing with the circuit conductors disconnected from the RCBO?

Yes, it still fails the test with conductors removed. In fact, the issue is with 2 RCBOs on the same board now. Seems odd as they are brand new.

 

[Strima]

What make and type of RCBO? A/AC/B???

 

[davidjtown]

What make and type of RCBO? A/AC/B???

Hager Type A

 

[Sintra]

Hager recommend testing at the device not at the end of the circuit see this link https://hager.com/uk/support/regulations-18th-edition/updated-rccb-testing

 

[davidjtown]

Hager recommend testing at the device not at the end of the circuit see this link https://hager.com/uk/support/regulations-18th-edition/updated-rccb-testing

Thanks for that. The link seems to indicate RCCBs prior to July 2019?

 

[nicebutdim]

Thanks for that. The link seems to indicate RCCBs prior to July 2019?

Stock can take some time to filter through the supply chain.

 

[davidjtown]

Replaced the RCBOs with new ones and still having the same problem. Tried it at the socket (outdoor), and at the DB with the conductors disconnected. RCBO still failing for additional protection at 5X In (56ms).

Any ideas what could be causing this? Cheers

 

[Strima]

What do Hagar say about testing their RCDs?

 

[newfutile]

are you testing at more than 250 ma we have had hagar rcd’s that don’t meet the required 40ms at 150

 

[davidjtown]

are you testing at more than 250 ma we have had hagar rcd’s that don’t meet the required 40ms at 150

I’ve tested at 250ma and 300ma. Still having the same issue. The RCBOs pass the test when MFT is set to AC.

 

[timhoward]

This seems to explain the problem fairly well:

Are you already using 5 x 50ma ?

 

[Deleted account]

So when a product is faulty we alter the test parameters to ensure it passes?

not sure on the legalities of this.

the excuse is manufacturers instructions say to do this.

what takes priority b.s.7671 or manufacturers instructions?

if the manufacturers instructions are requiring a greater degree of protection or better disconnection time this is fine, but in this case it is not.

very naughty!