Contactor wiring, break ring circuit through a stop button

[Sparkyy57]

Hi guys , I have to break a ring circuit through a contactor with an emergency stop button .. just want to double check my wiring in the diagram is correct .. haven’t done much of this sort of work so any feedback is appreciated.

 

[littlespark]

I would simplify things and place the socket RCBO in its own garage consumer unit, and the contactor on the supply to this CU.

What is the ring circuit used for? Power tools in a workshop?

 

[snowhead]

Who has decided the Circuit needs an E.M stop and what is the reason for this decision?
Has whoever made the decision thought of the consequences of the EM stop being reset and whatever is plugged in suddenly starting up?
As it would be on 13amp sockets, anything in the future could be plugged in and subject to uncontrolled restart.

Normally anything under Em Stop control would have individual no volt release protection to stop the above happening.

 

[Spoon]

Don't call it an Emergency Stop..... Just a Stop Button.
Next fit a Shunt Trip for the 32A RCBO.

 

[mainline]

Hi guys , I have to break a ring circuit through a contactor with an emergency stop button .. just want to double check my wiring in the diagram is correct .. haven’t done much of this sort of work so any feedback is appreciated.View attachment 108600

Why not use a latch off-key reset stop switch. ?

Emergency Stop Key Release Pushbutton Station IP65

Compact dimensions

www.cef.co.uk

 

[Sparkyy57]

Who has decided the Circuit needs an E.M stop and what is the reason for this decision?
Has whoever made the decision thought of the consequences of the EM stop being reset and whatever is plugged in suddenly starting up?
As it would be on 13amp sockets, anything in the future could be plugged in and subject to uncontrolled restart.

Normally anything under Em Stop control would have individual no volt release protection to stop the above happening.

It is a stop button that needs a key to disengage it again

 

[timhoward]

It is a stop button that needs a key to disengage it again

It’s more that when it’s disengaged it turns on again anything plugged in e.g an angle grinder could unexpectedly start up. There is stuff in regs about avoiding rotating machines starting without warning.
A possible solution might be to also change the sockets to non-latching RCD sockets so restoration of power requires each socket to be individually reset.
I still don’t hugely like this though as by adding a facility to stop everything it’s introducing multiple scenarios of a button unexpectedly starting things.

 

[davesparks]

Hi guys , I have to break a ring circuit through a contactor with an emergency stop button .. just want to double check my wiring in the diagram is correct .. haven’t done much of this sort of work so any feedback is appreciated.View attachment 108600

No, to the best of my knowledge that is non-compliant as the contactor will re-energize immediately when the stop button is reset.

There should be a minimum of a seperate reset button.

How far away from the RCBO is the contactor going to be? You'd be better off having a single 4mm conductor from the RCBO to the contactor.
If the contactor is far away from the OCPD then somebody could mistakenly add sockets to the ring before the contactor.

 

[davesparks]

Why not use a latch off-key reset stop switch. ?

Emergency Stop Key Release Pushbutton Station IP65

Compact dimensions

www.cef.co.uk

That would still need a seperate reset control.

There's a big issue with the key reset type of E-stop in that human nature is to leave the key in it so that you don't loose it. This means the button can't be as easily operated as it should be.

 

[mainline]

That would still need a seperate reset control.

Why ?

There's a big issue with the key reset type of E-stop in that human nature is to leave the key in it so that you don't loose it. This means the button can't be as easily operated as it should be.

If someone is silly enough to leave the key in after going to all the trouble of fitting a key to reset stop.

The same could be said for a tripped RCD or MCB do we need a separate reset for them as well ?