HELP! New CCU, RCD keeps tripping???

[Stormflex]

New Wylex dual RCD board

RCD 1 (80A 30mA)

32A Cooker
32A Kitchen ring
6A Upstairs lights

Have tried disconnecting all loads and connecting one at a time to see if I can determine which circuit is causing the problem but take your pick - whichever one I connect up trips the RCD.

RCD 2 (63A 30mA) with ring and downstairs light is all working fine.

 

[malcolmsanford]

Did you do any tests before changing the board. What was your IR for these circuits, Have you a "borrowed" neutral? Have you put a neutral on the wrong bar? Did you do a conitiuity test and could you have a NEUTRAL/EARTH or a NEUTRAL/LIVE reversed?

 

[WDMDL]

When you say disconnecting, do you mean neutrals as well?

What hapens if RCD2 is switched off when you try connecting any circuit?

How is the 2-way lighting wired?

Simon.

 

[Guest123]

Is the RCD itself fooked???

 

[Deleted member 9648]

As malcolm has already said sounds like the N in the wrong bar........BUT....if you cant sort this out you are not competant to be changing CU's.

 

[Stormflex]

Didn't do any testing prior to disconnecting old CCU. I'm doing it in my house and we've not had any issues prior to now.

Yes, have also tried disconnecting neutrals. Doesn't matter if RCD 2 is switched on or off.

It might be fooked!

No, no neutral in the wrong bar.

 

[beaky1066]

sounds like you have neutral to earth fault you need to do insulation resistance test between l+n and l+e and N+E before connecting them in one at a time....

 

[malcolmsanford]

Didn't do any testing prior to disconnecting old CCU. I'm doing it in my house and we've not had any issues prior to now.

Yes, have also tried disconnecting neutrals. Doesn't matter if RCD 2 is switched on or off.

It might be fooked!

No, no neutral in the wrong bar.

That could be a costly mistake as testing before a CCU change is perhaps the most important part of it.

So if all neutrals are in the right bar then it's a borrowed neutral, a reversed polarity, poor insulation resistance or a fooked RCD. the fooked RCD is quite simple swop them over and put the non tripping one in and see if it holds.

If it's nay of the others then testing would be the next step.

 

[Guest123]

Seriously, check the RCD before you go dismantling any circuits. It's not unheard of for wylex RCD's to be faulty out of the box.

 

[ukpablo]

swap the rcd's, ie use the one that is ok and put it over to the side that is tripping! if this trips, then its not rcd, or ramp test both rcd's on the side that is working to see if both are ok?

 

[telectrix]

first thing i would do, swop the lights so they are on the same RCD. if that cures the problem, you have a borrowed neutrasl on the lights. most likely the 2 way landing light. either leave light circuits both on same RCD or rewire the offending circuit. all else fails, call in the A team.

 

[Stormflex]

Thankfully resolved. Fooked RCD. Most frustrating but you live and learn. Grateful to all for your sugestions - useful for the next time something similar happens.