IR test @ 250V across N & E bars?

[Stever_777]

If I test as in my title on an old board, what reading should i get that will not start tripping an new Rcd board

Steve

 

[Deleted member 9648]

You should test @500v....and a reading >1mohm should be obtained,if you are testing @250v to avoid damage to connected equipment you should note the departure on the cert,minimum reading is the same.But it is likely that a reading taken @250v will decrease @500v so is not a reliable indicator of trur IR.
Readings much lower than 1meg will not cause nuisance tripping generally....remember a few years ago the minimum was 0.5megs.....I would only expect problems with readings <0.4megs. Such low readings will not comply with the regs though and should be improved.

 

[Stever_777]

You should test @500v....and a reading >1mohm should be obtained,if you are testing @250v to avoid damage to connected equipment you should note the departure on the cert,minimum reading is the same.But it is likely that a reading taken @250v will decrease @500v so is not a reliable indicator of trur IR.
Readings much lower than 1meg will not cause nuisance tripping generally....remember a few years ago the minimum was 0.5megs.....I would only expect problems with readings <0.4megs. Such low readings will not comply with the regs though and should be improved.

If I test between live conductors and earth then my readingis going to be more reliable.

 

[Sparky Ninja]

If I test as in my title on an old board, what reading should i get that will not start tripping an new Rcd board

Steve

Use ohms law.

230/0.03 = 7667 ohms. = 0.007667 Mega-ohms (assuming 30mA RCD)

So, transposed, any resistance value less than that will cause the device to operate.

 

[Stever_777]

Use ohms law.

230/0.03 = 7667 ohms. = 0.007667 Mega-ohms (assuming 30mA RCD)

So, transposed, any resistance value less than that will cause the device to operate.

Ahh duuhh! sometimes i cant see the wood from the tree`s.

Thanks widdler