RCB blowing,

[Ian57]

Hello, I am hopeful that somebody can give me some info with regard to RCBs and MCB since I have a small problem (I think), details as follows:

I have a MK consummer unit populated with RCBs and MCB and I am extending the lighting circuit which is protected by a 6amp MCB.

Before extending the cable I switched off the 6A MCB and commenced work, during the work, the earth and neutral wires touched and the RCB tripped, which surprised me somewhat. I reset the RCB and checked the voltage between the earth and neutral and there is nothing to speak about but each time I short out the earth and Neutral the RCB trips. Is this normal? I had assummed that earth and neutral would be at the same potential. Any help would be greatly appricated.

Ian

 

[Fleeting]

Perfectly normal I doubt there isn't an electrician about who hasn't had it happen to them.

 

[Barx]

Yep, all normal. Technically created an earth fault between earth and neutral. An MCB only isolates the Line (Live) conductor.
The modern day electrician fears the cpc (earth) more than the Line these days. On split RCD boards anyway. For this exact case. working away on lights, etc and end up tripping RCD and knocking the RCD out when the customer is working or doing something else important with socket power.

 

[Andy™]

normal

 

[Sharpend]

Some of the smart electricians actually disconnect the circuit they are working on to prevent such a scenario

 

[Andy™]

who are these 'smart electricians' you speak of?

 

[Sharpend]

I for one! I obviously received proper training

 

[Barx]

Some of the smart electricians actually disconnect the circuit they are working on to prevent such a scenario

Where's the fun in that?
I like to play "don't touch the neutral".

 

[Geoff1946]

Think through the way it happens. This is also an important lesson in future "random trip" fault finding.

 

[kerching]

Where's the fun in that?
I like to play "don't touch the neutral".

Wuss..it's not touching it that's the issue, it's touching something else or Earth at the same time

 

[Andy™]

 

[Ian57]

Good morning, thank you all for taking the time to answer and allay my fears of a probable fault.

Ian

 

[Barx]

Wuss..it's not touching it that's the issue, it's touching something else or Earth at the same time

Yeah, I meant don't touch it with the earth. Good catch

 

[kerching]

Yeah, I meant don't touch it with the earth. Good catch

Wife said if I don't stop being so pedantic I'll have less and less friends
I said 'actually it would be fewer and fewer'