Discrimination

[m4tty]

Hi,

Will a 30mA RCD discriminate with a 100mA RCD or does the 100mA need to be time delayed?

Thanks

 

[ianmacd]

If the fault current is over 100mA then no it won't. as either/both could trip so to satisfy discrimination a time delayed one would be needed.

 

[kme]

I would disagree Ian.

Discrimination requires the upstream RCD to have a rated tripping current 3X the downstream. 30mA x 3 < 100mA, ergo the 100mA doesn`t need time delay, IIRC

KME

 

[ianmacd]

Wasn't that in the 16th?

 

[Andy™]

I would disagree Ian. Discrimination requires the upstream RCD to have a rated tripping current 3X the downstream. 30mA x 3 < 100mA, ergo the 100mA doesn`t need time delay, IIRC

KME

and i would disagree with you, and agree with Ian - if you have a fault of 150mA (for example), then both 30mA & 100mA will trip. if the 100mA was TD, then only the 30mA would trip.

i cant see how rated current x3 has anything to do with it - there is nothing to say fault current must be 1/3 or highest rated RCD!

 

[kme]

Section R105-5 in the technical manual has just been perused.

Ian -my apologies mate. You & Andy are, indeed correct.

KME

 

[Andy™]

Section R105-5 in the technical manual has just been perused.Ian -my apologies mate. You & Andy are, indeed correct.

KME

debate over by post 6? im used to 5/6 pages!

 

[Lurch]

[quote name='Andy

 

[Andy™]

It's not gone off in several directions yet.

yet. and providing it stays civilised, then it can go in as many directions as it wants

 

[kme]

Welllllllll - I`m going thatatway <<^^>>

 

[Doc Hudson]

[quote name='Andy

 

[Andy™]

It would appear that the thread is lacking any 'text-talk', making it to easy for you gents to answer the original clearly written question.Doc H.

i no exctly wht u mean!

 

[kme]

i no its gud intit. i cud tipe lyke it all time btw cos is eezyr

Phew! Took me longer to do that line than it did to do this one!

Thanks Doc

 

[Andy™]

i no its gud intit. i cud tipe lyke it all time btw cos is eezyrPhew! Took me longer to do that line than it did to do this one!

Thanks Doc

took me much longer to type the previous post too - having to stop and re-think about how to spell!