RCDs and IR testing...

[Carlos Arruda]

Good morning to all.

I believe that, this as being a general question, would be best suited in this section of the forum.

RCDs are meant to trip (30mA) in case of an imbalance of current (I) between the live and neutral.

So, an insulation test will confirm that;

1 - Live to Neutral = Un-balance (if there's a leak) therefore tripping the RCD.

2 - Live to Earth = NO return to neutral thus confirming an unbalance and again tripping the RCD. Or there still might be a return to neutral but with a small leak to earth, enough to make the RCD trip.

Please, as always, shoot away your comments. These are very much appreciated.

Regards,
Albert

 

[Darkwood]

What goes in must come out but you forget you're usually only testing the cable with an Isulation test so load will be disconnected (although not always 'heating elements' etc ).


If you get 10.66amps flow down the L then this should reflect exactly 10.66amps back through the N, any deviation to this will have leaked to earth and if >20mA then could trip a 30mA RCD.

RCD's do not detect leakage L - N in the case of a damaged cable or water ingress to a joint as it would not show any issue as the leakage is still present and matched in both L and N.
NOTE!.... A leak in the 3ph system can be between another phase and if only monitoring 1 phase then this would also trip the RCD but not really relevent for domestic and single phase systems.

Do please utilise the Trainee section as we cannot always protect you from flack as easily in the main forum and where we do it puts work in the hands of the Mods to keep an eye on your thread and to delete any members going astray so to speak (They prefer not to spend most of there time eating chocolate biscuits and sipping earl grey), we have a good team of Mentors in there including myself and your answers will just be as informed.

 

[telectrix]

a fault L-N will not trip a RCD. remember that the load is a resistance across L and N. the RCD detects an imbalance between the L current and N current. this could be caused by a fault from either L or N to the cpc, an exposed conductive part, an extraneous part, or even a current leaking to earth through your body, which last is the purpose of the RCD.

 

[telectrix]

carlos.with all due respect, posts like this should be posted in the trainee section. there you will find that help is more readily given without you getting any stick .

 

[Pete999]

Good morning to all.

I believe that, this as being a general question, would be best suited in this section of the forum.

RCDs are meant to trip (30mA) in case of an imbalance of current (I) between the live and neutral.

So, an insulation test will confirm that;

1 - Live to Neutral = Un-balance (if there's a leak) therefore tripping the RCD.

2 - Live to Earth = NO return to neutral thus confirming an unbalance and again tripping the RCD. Or there still might be a return to neutral but with a small leak to earth, enough to make the RCD trip.

Please, as always, shoot away your comments. These are very much appreciated.

Regards,
Albert

http://www.greenbrook.co.uk/pdf/pbcatpg21-22.pdf

 

[Carlos Arruda]

Hi all.

Apologies to all.

I thought it would fit the general forum discussion.

Clearly I was wrong.

I shall now use the trainee section of the forum from now on.

Many thanks everyone.

Regards,
Albert


P.S: Many thanks to all that have given their thoughts/comments. Much appreciated.

 

[telectrix]

Hi all.

Apologies to all.

I thought it would fit the general forum discussion.

Clearly I was wrong.

I shall now use the trainee section of the forum from now on.

Many thanks everyone.

Regards,
Albert


P.S: Many thanks to all that have given their thoughts/comments. Much appreciated.

not wrong, mate. just that this particular question would be better received in trainee. nothing wrong with posting in general.just that the trainee section gives you more latitude, considering your status.