Earth Leakage problem

[Lucien Nunes]

'n buitelander! Marvo, let vertaal dit vir ons...

 

[J.Spark]

Hahaha haha yeah I am sure lol!

 

[Marvo]

Is it the usual black CBI samite mount earth leakage breaker?

 

[J.Spark]

The din rail type....schneider electric make

 

[Marvo]

Then it's a standard 30mA RCD. Is it being used as the main breaker or is it just supplying the sockets?

The only way it can trip with the installation isolated is if there's power still on it from another source which is unlikely as you said you checked for supply voltage after isolating so something's not adding up.

Note for the UK guys, South African DB's (CU's) generally have all RCD's and MCB's supply at the top and final ccts connected at the bottom and it's common practice for the entire installation to have a single upfront 30mA RCD.

 

[J.Spark]

Yes only for sockets....but I find it strange that it trips like this....even trips with putting on some circuits which are not running through the earth leakage as well as when there is 0 voltage on the top.

 

[Marvo]

Yeah, it's not making sense, an RCD can't trip unless there's power coming from somewhere. Is there an inverter back-up system, solar pv system or UPS in the premises perhaps?

 

[J.Spark]

Nope.....nothing like that....I double checked voltage on top all the time to make sure because this confused me quite a bit. Never came across something like this. Very strange to say the least.

 

[Marvo]

I'd check for voltage on the load side as well. Do all the usual tests like megger test the circuits, test for crossed circuits/borrowed neutrals (continuity between circuits) and a leakage test with an earth leakage clamp meter around the L+N at the RCD.

With the RCD tripping when the power is isolated I'd suggest extreme caution, treat the DB and all circuits as live until you find the cause of that.

 

[J.Spark]

I did check on load side as well. No voltage. But will do all the tests again and double check on all again.....hopefully it has fixed itself overnight lol! One can only wish lol!

 

[Octopus]

Best that the op updates his location to avoid future assumptions

 

[J.Spark]

Morning guys.....these are a few pics of the set up..... top left is the ELCB....

 

[J.Spark]

Last night I bypassed the ELCB so that the client has power hence no wiring in the unit....

 

[J.Spark]

another pic

 

[Lucien Nunes]

If only we'd had the pics to start with. Let's recap:
In South Africa.
3-phase supply to board with TP main switch, unswitched neutral.
Loads (mainly or all single-phase) supplied from SP MCBs.
Supply side of MCBs hand-wired and SP busbar, not ready-made TP busbar.
12 circuits on blue phase fed via DP 30mA RCD, associated neutral bar arrangements not visible.
RCD trips with load on unprotected circuits and sometimes even with main switch off.
IR on all circuits thought to be OK.

VOELCB was a red herring!