Dangerous upgrade to crabtree rcbo's

[Phillip]

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..

 

[Phillip]

Sometimes in the real world, you will have to work on live equipment. Being it domestic or commercial. You can talk regulations and safety all you like. But the real world is not like that.

 

[sheppertonspark]

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..

It sounds to me as though you have uncovered a design fault. The internal trip mechanism must be fed from the live side of the breaker , not the protected side. Quite rightly you would not expect the neutral tail to be "live" when the circuit breaker is off.

 

[mrloy99]

WE can go on about live working, until the cows come home.
Simple fact is, an RCBO is a means of isolation.
This particular RCBO is not doing what it should be doing.
If I were to isolate the circuit protected by this RCBO to swap over a damaged socket front, the Neutral would be live as would every other Neutral connected to the Neutral bar.

Only if the neutral is disconnected at mains

 

[telectrix]

could this be a similar scenario to a circuit that has L energised with a load in circuit, and the N floating (dissed). due to the no current flow = 0 V drop, the N is sitting at 230V. this disappears when N is connected. in the RCBO case, the load would be the internal gubbins in the RCBO.?????

 

[Alrebcon180]

could this be a similar scenario to a circuit that has L energised with a load in circuit, and the N floating (dissed). due to the no current flow = 0 V drop, the N is sitting at 230V. this disappears when N is connected. in the RCBO case, the load would be the internal gubbins in the RCBO.?????

Yes think that is exactly what is happening just that you don't normally think of your rcbo as a load but more of a disconnection device that if its switched off u wouldn't expect anything to be live..

 

[johnduffell]

Yes think that is exactly what is happening just that you don't normally think of your rcbo as a load but more of a disconnection device that if its switched off u wouldn't expect anything to be live..

An isolator only isolates the outgoing terminals. The fly lead is an incoming terminal.
If you turn off an isolator it only isolates the outgoing terminals. the incoming line terminal is certainly of course still at phase voltage, and if there is any circuitry the incoming neutral would be live too if parted. If it's not parted it would be close to installation earth voltage.

This example can repeat in other situations so do take care - imagine a Usb double socket or similar. If you switch the socket off and leave the line connected and part the neutrals somewhere, you'd expect to get a shock from the neutral.
All current carrying conductors are to be treated as live for this reason, including neutral.

Glad you're ok and thanks for the reminder of the risks.

 

[Alrebcon180]

An isolator only isolates the outgoing terminals. The fly lead is an incoming terminal.
If you turn off an isolator it only isolates the outgoing terminals. the incoming line terminal is certainly of course still at phase voltage, and if there is any circuitry the incoming neutral would be live too if parted. If it's not parted it would be close to installation earth voltage.

This example can repeat in other situations so do take care - imagine a Usb double socket or similar. If you switch the socket off and leave the line connected and part the neutrals somewhere, you'd expect to get a shock from the neutral.
All current carrying conductors are to be treated as live for this reason, including neutral.

Glad you're ok and thanks for the reminder of the risks.

 

[MFS Electrical]

Yep done that and also broke both a new one and an old one apart and you can clearly see the neutral fly lead In the new one is connected to the live bus bar prong.

Did you take pictures? we like to see

 

[Alrebcon180]

Did you take pictures? we like to see

Yes they are on this thread somewhere