Can't reset the RCD with any MCB's on - Faulty RCD?

[DPG]

Good post from Marconi.

And from now on the all RCBO board will be known as the 'Murdoch Solution'. Brill.

 

[littlespark]

Yeh Macaroni’s posts are always full of big long technical words. Unlike some. Eh Buzz

Hopefully you can find the culprit.
Turn off the power. Do all the street lights outside go off too?

 

[Geoff101]

Alas and alack, simply opening a single-pole mcb does not disconnect the neutral wiring. So, with any but only one mcb turned on and then closing the double pole RCD all the final circuits line and neutral circuitry are in play as far as electrons are concerned including current paths to earth and especially transient currents as these circuits are made live but not energised to full mains(240V) potential - apart from the circuit of the closed mcb.

My simple experiment would be to disconnect the L, N and cpc of the induction hob circuit at the CU ; it's my number one suspect for your problem because of its in-line power EMI filters and how they respond to transient voltages between L and N and L and E and N and E. Then, with all mcbs closed try re-energising the board - I suspect the problem will go away. Put the induction hob on its own rcbo. If not I think you will find a number of mcbs can now be closed and then energised. Final circuits which might give you a problem will have white goods, microwaves and some types of computer equipment which use the earth/cpc for EMI filtering purposes.

Herein lies a problem - the sole RCD is also the Main Switch. What needs to be arranged is a Main Switch which supplies the RCBO for IH and the RCD for all the remaining mcbs. I don't think you have room fit an a new Main Switch and an new RCBO unless one combines some final circuits. If it was me I would replace the CU with a Main Switch and dual RCD board plus RCBO for IH or plump for the top end aka Murdoch solution - Main Switch and all RCBOs for final circuits.

(Please take a photo of your cut out, earthing bar and meter arrangements so we can try and discover the earthing system in use.)

Thanks. Really helpful. I’ll try that tomorrow when I get time.
In terms of following your advice for the future set up and keeping things as simple as possible would it be in order to add a main switch which then fed the existing consumer unit and also split to feed a new unit with single RCBO to feed the IH. Obviously then moving the IH circuit from the old CU and leaving a spare way?
Prob not the neatest way of doing it but would it meet requirements?

 

[Deleted member 9648]

You also have a standard bonding clamp connecting your main earth to the cable sheath. This is not acceptable as a means of connection and can be dangerous as it will compress the cable. Do not disturb it, and contact your supplier to arrange for a proper clamp to be installed.

 

[Wilko]

Picking up on Wirey's thought - I hope there is a connection back up to the Consumer Unit somehow. I could be totally incorrect, but I see the 2 conductors going down (to gas and water perhaps) but none coming up with the meter tails. Is there one in that trunking perhaps?

 

[Geoff101]

Thanks. Really helpful. I’ll try that tomorrow when I get time.
In terms of following your advice for the future set up and keeping things as simple as possible would it be in order to add a main switch which then fed the existing consumer unit and also split to feed a new unit with single RCBO to feed the IH. Obviously then moving the IH circuit from the old CU and leaving a spare way?
Prob not the neatest way of doing it but would it meet requirements?

View attachment 45909

View attachment 45910

Following my previous post maybe something like this and consider moving both the IH and oven on this with RCBOs in it?

I Wylex NM206/63 | 2 Way Consumer Unit | Fast UK Delivery | Buy Now - https://www.electricpoint.com/wylex-nm206-63-2-way-63a-main-switch-metal-consumer-unit.html?utm_source=googlebase&utm_medium=datafeed&utm_campaign=google-shopping&gclid=Cj0KCQiAxNnfBRDwARIsAJlH29DCxq2ooi0EIAXSIGX2hcWs2gkE2dsm1F58XDREtFkBLCZmw_lrIOkaAnITEALw_wcB

 

[Geoff101]

You also have a standard bonding clamp connecting your main earth to the cable sheath. This is not acceptable as a means of connection and can be dangerous as it will compress the cable. Do not disturb it, and contact your supplier to arrange for a proper clamp to be installed.

Interesting. This was fitted by the supplier about 4 months ago.....!

 

[Geoff101]

Picking up on Wirey's thought - I hope there is a connection back up to the Consumer Unit somehow. I could be totally incorrect, but I see the 2 conductors going down (to gas and water perhaps) but none coming up with the meter tails. Is there one in that trunking perhaps?

It’s in the trunking....

 

[Silly Sausage]

Ooooh, is that a 'smart meter' I see before me?
There's a recent thread along a similar line of RCDs tripping in proximity to SMs.
Is there any correlation here?

 

[Geoff101]

Ooooh, is that a 'smart meter' I see before me?
There's a recent thread along a similar line of RCDs tripping in proximity to SMs.
Is there any correlation here?

Interesting! It’s always tripped on reset but only recently has been tripping at other times. I thought this correlated to power interruptions but can’t be sure on all of them. The smart meter has only been there a few months so there is a possible connection..... how to tell though.....?!