RCBO tripping after spur distribution board has already tripped

[ses]

You said he ran a 10mm swa with a spur to a socket what size was the spur

 

[Octopus]

(Oh I just remembered that when I ran the wire for the lighting radial circuit I accidentally used 3 core and earth instead of 2 core, but I told him this and he so he just didn't use the third wire. I don't think this could be the problem, it isn't the lights I switched on anyway.

I thought you stated you didn't do any of the work. Make up your mind and stop telling stories.

This reminds me of a thread a while bacak where the OP stated he was checking what the sparky was doing, etc, etc then a couple of months later posted he was getting his part P registration.

 

[Susie]

Murdoch you have PM. In it I have explained my background to you further as I do understand your scepticism, but I hope that you will give me the benefit of the doubt on this occasion. Putting a bit of cable in a ceiling before it gets plastered is very different from touching any kind of live installation, I simply am not so stupid as to try that. I like to know how things work, and I have really appreciated the time other members have taken to help me increase my understanding. Again I will say I am not askign HOW to do things but WHY. This is curiosity nothing more.

 

[Octopus]

Murdoch you have PM. In it I have explained my background to you further as I do understand your scepticism, but I hope that you will give me the benefit of the doubt on this occasion. Putting a bit of cable in a ceiling before it gets plastered is very different from touching any kind of live installation, I simply am not so stupid as to try that. I like to know how things work, and I have really appreciated the time other members have taken to help me increase my understanding. Again I will say I am not askign HOW to do things but WHY. This is curiosity nothing more.

And I've read it and was very tempted to copy and paste it into this thread!

 

[Des 56]

Ok, so deep breath, here we go;

I now know that bonding and earthing are different. A TT earthing system is one where the user doesn't earth via the supply from the electrical company but provides his own earth in the form of an electron rod, aka copper rod aka earth rod.
[I have an earth rod at BD1 as well as BD2].
Then I looked at earthing and the standard method of tying the electrical supply system to earth is to make a direct connection between the two. "This is usually carried out at the supply transformer, where the neutral conductor (often the star point of a three-phase supply) is connected to earth using an earth electrode or the metal sheath and armouring of a buried cable".
So if the cable runs between BD1 and BD2 and at each board the earth and neutral are connected, then if the SVA armouring is also bonded to earth at each end, then it completes the loop and current can flow through the armouring?
But would this not be the same with the earth cable in the insulated core of the SVA cable? Ah no it wouldn't because it is not bonded, and it is the bonding that would complete teh loop from one earth rod to the other and complete a circuit. I think!
Wait I still haven't answered why it should be bonded to earth at BD1 end and not BD2 end.

Well.even if you were telling porkies and Murdoch is correct,at the least you are trying to understand why things are done a particular way and where the theory relates to these particular ways,instead of going in blind and installing willy nilly as many home owners are known to have done,"it works don't it"

quote
Ok Sintra and Des, how did I do, am I close?


Um Not yet,but keep at it and your understanding will improve

 

[Sintra]

Have a look at what you can find regarding extraneous conductive parts and bonding back to the main earth terminal.

By the way what is the construction of the outbuilding block, timber, steel etc. and does it have any other services like a water or gas supply?

 

[Susie]

Concrete raft foundation and clad timber frame. No gas or water.

Thank you for the reply, and thank you for the pointer I shall go and google!

 

[Susie]

Well.even if you were telling porkies and Murdoch is correct,at the least you are trying to understand why things are done a particular way and where the theory relates to these particular ways,instead of going in blind and installing willy nilly as many home owners are known to have done,"it works don't it"

quote
Ok Sintra and Des, how did I do, am I close?


Um Not yet,but keep at it and your understanding will improve

Argh, I feel like a school kid! Ok so I will keep looking. Thank you!

 

[not clever]

Do away with the rcbo's/rcd in the workshop & use MCB's. Keep the rcbo for the submain at the house end (will be a pain the the backside when it trips & you have to wander back to the house)this will provide 30mA protection for submain & all workshop circuits.
Connect swa to earth by using the gland banjo or a earthnut, no worries if its both ends or one end as you say the house supply is also TT.

 

[richy3333]

And I've read it and was very tempted to copy and paste it into this thread!

Am Ithe only one gagging to know what she said?

 

[UNG]

I'm really beginning to lose the will to stay on this forum this is not a thread it's turning into something of a a farce