Wiring a emergency stop.

[Homerjh]

Hi all, back after a long asbence (not been in jail, just a manic 2019!)

I have finally bought an emergency stop button (https://www.amazon.co.uk/dp/B07JGX7HM6/ ... 11_TE_item) and an extention lead (https://www.amazon.co.uk/dp/B078Y4JNXP/ ... 11_TE_item) so i can have some sort of shutdown option as the plugs are behind the lathe/scrollsaw and there is no quick way to shut the power off.

so my question is, i am expecting the button to have space for 2 lines, NO and NC, so i am assuming that the safest is to have the NO line with the live (so no power past when open) and the NC as the earth and the earth be left in tact and not cut?

thanks

 

[CHJ]

Hi all, back after a long asbence (not been in jail, just a manic 2019!)

I have finally bought an emergency stop button (https://www.amazon.co.uk/dp/B07JGX7HM6/ ... 11_TE_item) ……..
so my question is, i am expecting the button to have space for 2 lines, NO and NC, so i am assuming that the safest is to have the NO line with the live (so no power past when open) and the NC as the earth and the earth be left in tact and not cut?

thanks

You had best get someone with electrical knowledge to wire it up for you.

I think your understanding of NO and NC convention is mistaken.

This type of switch is only safe to use as an isolation device if your lathe already has an NVR release switch in its controls.

You are correct in that the earth must remain continuous.
Whether just the LIVE or Live and Neutral are broken by the NC contacts will depend on whether there are one or two sets of NC contacts in the switch unit.

 

[sunnybob]

You do not understand the wiring.
The earth must be continuous at all times and must NOT EVER go through switch terminals. (hammer)

What you have is an emergency stop or "panic" button. It will shut down everything connected to it until you manually reset it. It is NOT a NVR safety switch.

 

[Homerjh]

the button is just to cut power when pressed, the lathe does have a NVR (i think it does anyhow, will check in a tic).

i will double check all wires/etc and so if the button has both sets, so NO and NC then only the live should go via the NC, so when it is pressed it opens the circuit and breaks power and leave the NO connections empty.

if it has a NO line then if wired this way, it would only present power if the button was pressed in (which is not what i want), in this case an example would be an alarm to activate when pressed.


thanks

 

[EddyCurrent]

This type of switch is only safe to use as an isolation device if your lathe already has an NVR release switch in its controls.

In the electrical field the word 'isolation' has a specific meaning and an emergency stop switch definately does not provide isolation.
For a lathe of this type, isolation would consist of removing the mains plug from it's socket.

 

[Homerjh]

The lathe doesnt have an NVR so will be looking to get one fitted (Record power lathe, model 0?) as just has a standard on/off switch, its my scrollsaw that has one.

the switch/stop is just so i can get the power disconnected quickly, it isnt intended to be used as a on/off switch for regular use instead of anything else.

thanks all

 

[CHJ]

…..
the switch/stop is just so i can get the power disconnected quickly, it isnt intended to be used as a on/off switch for regular use instead of anything else.

As your lathe does not have an NVR switch then you must ensure that it is a LATCHING Stop switch that requires a deliberate and distinct mechanical latch release to activate it again, even then it must be used with caution as resetting it with Lathe switches still in the ON position will see the lathe starting immediately.

If it is only a spring loaded push switch without a mechanical latch then it will only break the connection momentarily whilst held down. (suitable to trigger an NVR switch)

 

[Homerjh]

It looks like from the picture that it may latch but will check, as no point otherwise, and as you said without a NVR it will be useless.

 

[Homerjh]

All wired up (should the lights flicker when I press it?? Joke!), mounted next to the lathe screwed to the worktop.

Works perfectly, it is a latched stop so works with my old non-nvr lathe and a lot nicer to use than trying to use the original switch when needing to switch the lathe off.

Well worth the small cost.