Emergency stop buttons on workshop ring main.

[CarbonPepper]

Please forgive terminology. This is a DIY question.

Domestic Workshop in new (new to us - small charity) premises that has its own RCD consumer unit with a ring main circuit and a lighting circuit. Has a few single-phase bench tools, saws, pillar drill etc. It's an odd one, it really is domestic.

It was suggested it might be an idea to have a couple of emergency stop buttons.


Then comes the interesting bit. How dodgy is the suggestion that these could be wired using the NO connections in the switch, to short the ring main to earth? A spark has apparently suggested this (Please don't shoot the messenger ) but I need reassurance.

 

[James]

Absolutely not,
No way
Not acceptable.

Are you sure this spark is an electrician?

Edit:
p.s. If I was not clear enough in the above, I don't think it is a really good idea!!

 

[Avo Mk8]

How dodgy is the suggestion that these could be wired using the NO connections in the switch, to short the ring main to earth? A spark has apparently suggested this (Please don't shoot the messenger ) but I need reassurance.

That is a terrible idea. As per James.

E-Stop circuits need proper engineering design. The hardware - switches & relays etc. are specially made for their safety role, fault tolerant, and the design should be done by someone competent in safety systems.
It sounds as if you may have 'members of the public' (for want of a better phrase) using the equipment, so you probably have duties under health and safety legislation here, no matter how 'domestic' the setup may appear?

And doing this madcap idea could mean a person pushing the button gets their hand taken out by an exploding switch if the circuit breaker doesn't save them first.

 

[CarbonPepper]

Absolutely not,
No way
Not acceptable.

Are you sure this spark is an electrician?

I have my doubts

 

[littlespark]

i think the so-called electrician is "pulling a leg" or two.

The stop button should be wired to a contactor which breaks the supply to the machines, and needs manually reset.... Designed properly, as already mentioned.

He has suggested wiring the stop to purposefully link live to earth, which would trip the rcd....

methinks he is a joker.

 

[James]

He has suggested wiring the stop to purposefully link live to earth, which would trip the rcd....

methinks he is a joker. IDIOT

corrected that for you.

 

[CarbonPepper]

It could be a wind up I suppose. But sadly I doubt it. Thanks guys.

 

[littlespark]

It could be a wind up I suppose. But sadly I doubt it. Thanks guys.

if thats the case.... dont let them back to do any work... thats just dangerous..... against regs and likely to damage the rcd after so many trips

 

[James]

It could be a wind up I suppose. But sadly I doubt it. Thanks guys.

This is a forum that has plenty of real electricians and electrical engineers, if you post your location, someone may be able to help you with some sensible advice and a quote to make it right.

 

[MDJ]

A spark has apparently suggested this

No I am afraid not, James post after your initial reply says it all from all of us

 

[CarbonPepper]

So it went something like this. My knowledge is very old, pre part P and on 3 phase industrial stuff. I remember quite a lot, but largely it's to know what I don't know.

Anyway some other layperson, purely when discussing where to put the switches, suggested just adding it to the ring, to which I replied that's not going to work, because it's a ring. Power will still flow, you have to isolate the entire circuit. There are ways, but we're going to have to run new cables and get some expertise. People don't like having cables run.

Anyway someone knows someone, and off they went to get a remote opinion. No-one has been out. No harm done, but at least now at the next meeting I can insist on expert input.

 

[mainline]

So it went something like this. My knowledge is very old, pre part P and on 3 phase industrial stuff. I remember quite a lot, but largely it's to know what I don't know.

Anyway some other layperson, purely when discussing where to put the switches, suggested just adding it to the ring, to which I replied that's not going to work, because it's a ring. Power will still flow, you have to isolate the entire circuit. There are ways, but we're going to have to run new cables and get some expertise. People don't like having cables run.

Anyway someone knows someone, and off they went to get a remote opinion. No-one has been out. No harm done, but at least now at the next meeting I can insist on expert input.

If it's going to be an emergency stop and not just a stop, then other factors come into play depending on what sort of machines the emergency stop is on, for instance it may need a braking system.