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Discuss Dangerous upgrade to crabtree rcbo's in the The Welcome Forum area at ElectriciansForums.net

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Has anyone installed the new compact rcbo from crabtree and noticed a flaw that they have introduced that doesn't exist on the older larger model starbreaker rcbo..
The basics of it are that the new compact rcbo when plugged into the busbar in a circumstance that many will come across where you can't turn off the mains once the rcbo is clicked in but still in the off position the neutral tail actually bacomes live and has upto 170 volts on it, therefor if u touch this and then the neutral bar you become part of the circuit and get a shock..
 
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snowhead

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Mentor
Presumably you'd had a shock in this situation?

So that's fitting the RCBO with it switched on, into a live board and wondering why the Rcbo neutral tail becomes live?
 
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  • #3
Nope the rcbo is in the switched off position if u read what I put.. If u going to try be clever please read correctly first
 
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  • #4
And as I said the previous older style which they have just stopped making do not give any voltage through the neutral at all so they have obviously removed something and made this what I consider a dangerous rcbo to install if you can not turn off the whe of the mains to replace one faulty rcbo
 

netblindpaul

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Mentor
Arms
And as I said the previous older style which they have just stopped making do not give any voltage through the neutral at all so they have obviously removed something and made this what I consider a dangerous rcbo to install if you can not turn off the whe of the mains to replace one faulty rcbo
EAWR89 disagrees with you.
 

happysteve

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Arms
Esteemed
I think a couple of the comments - whilst highlighting the dangers of working live, perhaps against statutory regulation - are perhaps a little unfair to the original poster. For example:

- turn off main switch, lock off
- remove DB cover
- confirm all potenitally live connections (when power is restored) can't be touched (better than IP20, i.e. recessed screws on protective devices, no excess copper showing); this is a Starbreaker board, so no busbar cover (recessed contacts to better than IP20)
- prove dead
- insert new RCBO into (dead) bus bar
- lock off new RCBO
- unlock main switch to retore power to other circuits

At this point, you've got a flying neutral lead flapping about, which the OP says is live (even with the RCBO turned off). Personally, I'd not be happy with a very flexible bit of wire flapping about when the tops of the other protective devices are live (they might be finger-proof, but the end of the RCBO neutral tail could easily drop down on one of them, might be a shock/arcing risk)... but on the other hand, I certainly wouldn't expect it to be live, if I had locked off the RCBO.

It would be like turning off and locking off a circuit breaker, and then removing the neutral (for that circuit) from the neutral bar - I certainly wouldn't expect it to be live (on a TN system anyway) unless it was back-fed from another circuit (e.g. "borrowed neutral").

That's my take on it anyway, and I think it was probably worth bringing to the attention of the community in general.
 

LeeH

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Arms
Esteemed
The only thing you are missing is the OP’s suggesting that the danger is with the new design and not the action of working on a live DB.
 
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  • #9
In answer to netblindpaul even in those regulations they take into account working live where the cost/ hassle of switching off a supply compared to the risk involved is taken into account and in certain cases I would consider working on a live distribution board to replace one faulty rcbo and like David prosser said if all things had been done to lock off and make safe u still wouldnt expect the neutral tail to be live.
I work in the real world where sometimes you can't take down a server or turn off a machine because of the cost/business implications and when working on crabtree boards felt safe in the knowledge that I was pretty safe to do so. Not Now.
 
H

Harry_P

In answer to netblindpaul even in those regulations they take into account working live where the cost/ hassle of switching off a supply compared to the risk involved is taken into account and in certain cases I would consider working on a live distribution board to replace one faulty rcbo and like David prosser said if all things had been done to lock off and make safe u still wouldnt expect the neutral tail to be live.
I work in the real world where sometimes you can't take down a server or turn off a machine because of the cost/business implications and when working on crabtree boards felt safe in the knowledge that I was pretty safe to do so. Not Now.
So now that you do know you aren't safe does that change your position regarding the inconvenience of isolating the supply to keep yourself safe? Cost never comes before safety that's the real world
 
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  • #11
So now that you do know you aren't safe does that change your position regarding the inconvenience of isolating the supply to keep yourself safe? Cost never comes before safety that's the real world
As per the text again in the real world of electrical work which I have been doing for 30 years you do have to work on a live fuse board now and again and anyone who has worked In a commercial or school environment will agree or just lie to go along with the people who " have never worked on anything live".. And yes to answer your question it does now mean that if I have to replace one of these items I will have to rethink how I go about this..
This is the reason I never post on these sites because I was trying to give a heads up to anyone who might be in a situation where they are replacing one I didn't want them to receive a shock like I did. But unfortunately most people on this site prefer to be argumentative and pick on the isolation side rather than actually pass on some info that might help someone..
 
Can you not connect the neutral fly lead before connection to the busbar?
I don't suppose you have contacted Crabtree technical.
I have fitted an mcb and rcbo today both in live boards.
 

David Prosser

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Arms
Esteemed
In answer to netblindpaul even in those regulations they take into account working live where the cost/ hassle of switching off a supply compared to the risk involved is taken into account and in certain cases I would consider working on a live distribution board to replace one faulty rcbo and like David prosser said if all things had been done to lock off and make safe u still wouldnt expect the neutral tail to be live.
I work in the real world where sometimes you can't take down a server or turn off a machine because of the cost/business implications and when working on crabtree boards felt safe in the knowledge that I was pretty safe to do so. Not Now.
I said no such thing !
 

Strima

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Arms
Esteemed
Working live argument aside, the neutral flylead should not be carrying any voltage especially when the RCBO is turned off.

As Westward10 has mentioned could you not connect the neutral first?

I think the OP is right to highlight this issue to us as there is a risk of electric shock.

Have you spoken to the manufacturer?
 
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