Earth Leakage Breaker (RCD) Tripping

[Ippi591]

Thanks for that info AndyD, very informative (even 5 years later). I have a question though, is there a limit on how many milliseconds the RCD should take to trip? I did a check across 37 installed RCD's and the time range from 9 to 203 milliseconds.

[Ippi591]

I found a document, VC8035 From 1987, Compulsory Specification for Earth leakage protection units.

It lists the following times:



Are they still relevant?

[MCP]

If there's anything I missed, anything that's inaccurate or anything that doesn't read too well grammatically please let me know.

Andy - that was an amazing summary that prompted me to sign up and congratulate you.
This is my first ever post.
And also to ask a question which I hope is not deemed too dumb.
How many circuit breakers can one connect on a bank supplied by a single RCB/EL?
Is there a limit or does one break it up for easier management in future fault-finding?
The DBs I have seen mostly have only the plug circuits on EL. Typically 20A C/Bs.
eg - I have seen DBs with 10x20A C/Bs on a single EL. Others with max of 5x20A C/Bs on EL and with 2 or 3 "banks" of these.
Most are "old style" black Samite but some are "new style" DIN rail.
Thx
C

[GCE]

Andy - that was an amazing summary that prompted me to sign up and congratulate you.
This is my first ever post.
And also to ask a question which I hope is not deemed too dumb.
How many circuit breakers can one connect on a bank supplied by a single RCB/EL?
Is there a limit or does one break it up for easier management in future fault-finding?
The DBs I have seen mostly have only the plug circuits on EL. Typically 20A C/Bs.
eg - I have seen DBs with 10x20A C/Bs on a single EL. Others with max of 5x20A C/Bs on EL and with 2 or 3 "banks" of these.
Most are "old style" black Samite but some are "new style" DIN rail.
Thx
C

Per regulations you can put as many CB after the Earth leakage as you want to - The Earth leakage has to be overloaded protected so in a domestic situation usually 63Amp isolator type earth leakage an it would have a max of 63Amp CB protecting.

Good practice is to install limited CB after the earth leakage and that is very dependent on usage - Every appliance has a leakage to earth so eventually an earth leakage will trip purely due to the qty of appliances leaking to earth , some worse than others

In smaller house you would do 1 ELU and 3 plug circuits , In a bigger house maybe 2 earth leakages or 3

My previous house I had 5 Earth Leakage units , where I squat now I have 3 and really only need 1 but I don't like struggling when I get home , I prefer drinking a beer in peace