RCD throwing Zs readings off

[scott-fitz]

installed a new dual rcd cu today and on completeing my tests I noticed the zs values were slightly above the max permitted by bs7671.

All my other readings, r1+r2s ect were fine and the ze was 0.2 off the top of my head.

took a zs reading off the load side of both rcds and both values came out around 1.03.

rcd funcional tests were fine and so too were the tripping times.

my question is, i'm i ok calculating the zs values and making a comment on my cert such as, "zs values calculated as rcd falsifying readings" ?

thanks guys

 

[IQ Electrical]

If your circuits were all protected by 30mA rcd/rcbo's then your maximum Zs can be taken as 1667 Ohms-just record the values exactly as they were measured.

 

[telectrix]

last week i had an RCD giving Zs as 341ohms when Ze was 0.16ohms!!!!! so you're not doing badly .

 

[scott-fitz]

If your circuits were all protected by 30mA rcd/rcbo's then your maximum Zs can be taken as 1667 Ohms-just record the values exactly as they were measured.

off course! feel stupid for overlooking this now! would you still throw a little comment in explaining that zs values exceed that permitted for mcbs but circuits protected by rcd, or just assume that he who next looks at the cert should know why the values are good?

 

[IQ Electrical]

off course! feel stupid for overlooking this now! would you still throw a little comment in explaining that zs values exceed that permitted for mcbs but circuits protected by rcd, or just assume that he who next looks at the cert should know why the values are good?

It can't do you any harm to add a little note.