Does a 20amp emergency stop button exist?

[j_arney]

If this is paid work and invoiced you better have a paper trail of proof to who designed it and takes responsibility otherwise it still falls at your feet, imagine is someone is injured or worse, do you expect them to put their hands up to possible dangerous installation practices or point the finger at you showing your invoice.

If you are invoicing it it would be an idea to make it part of the invoice declaring no responsibility for design or safety making it clear it was requested, this would not remove you from and possible legal action because unless you have a full paper trail to this the responsibility lies on you to assess any requests meet standards applicable, so tread carefully I

This is intended as a constructive comment. Where possible I would have fused down the 20 amp circuit for the coil. Then one MCB safely isolates the lot. It sounds as though you'd have to turn off two MCB's for everything at the contactor to be safely isolated?

i did consider that option, I don’t regularly install contactors and seen it done that way a few times before. Will take on board though

 

[mainline]

Do not rely on an MCB for safe isolation

 

[timhoward]

A Mcb does not provide safe isolation, especially on a TT earthing system

After all, we wouldn't want the OP thinking that It's OK to do so he could end up killing someone

I think you know my point was really about multiple sources of supply.

( I'll take your point that an MCB isn't always suitable for isolation. It isn't as simple as saying it never is though - after all if that were the case it wouldn't appear in table 537.4 with a "Yes". )

And to be clear, I wasn't meaning to refer to "safe isolation" in the sense of the procedure to ensure it is safe to commence working. I said "safely isolated", maybe unwise words but I meant there are two things to turn off not one, a trap for the unwary and reg 537.1.2 could be worth considering.

 

[Mike Johnson]

I’ve been asked to provide an emergency stop button for a circuit rated at 20amps. I’ve never installed one before and only really found 10amp buttons at my local wholesaler. I can put a contactor in, no problem but was just interested to see if you can get them?

Have a look for a NVR switch (No Volt Release) they are on most woodworking machines that can cary high loads, this one is rated at 18amp: Axminster Workshop KJD17B NVR Switch 230V 1ph - https://www.axminstertools.com/kedu-kjd17b-nvr-switch-230v-1ph-102532?queryID=caac039e86bf11f04a93756c659eea3e

 

[mainline]

I think you know my point was really about multiple sources of supply.

( I'll take your point that an MCB isn't always suitable for isolation. It isn't as simple as saying it never is though - after all if that were the case it wouldn't appear in table 537.4 with a "Yes". )

And to be clear, I wasn't meaning to refer to "safe isolation" in the sense of the procedure to ensure it is safe to commence working. I said "safely isolated", maybe unwise words but I meant there are two things to turn off not one, a trap for the unwary and reg 537.1.2 could be worth considering.

Yes I get the " I wasn't meaning safe isolation when I said safely isolated

Most of this thread has been about risk assessment and a rant at me about not knowing what sort of circuit it's being used for etc etc.

But it seems to be OK for someone else to then give misinformation and say that a mcb is fine for isolation when it clearly isn't without knowing the circuit.

537.4 it clearly states for TN not TT even then using a mcb for safe isolation isn't really safe as the circuit could have a borrowed neutral for instance.

 

[mainline]

Have a look for a NVR switch (No Volt Release) they are on most woodworking machines that can cary high loads, this one is rated at 18amp: Axminster Workshop KJD17B NVR Switch 230V 1ph - https://www.axminstertools.com/kedu-kjd17b-nvr-switch-230v-1ph-102532?queryID=caac039e86bf11f04a93756c659eea3e

Woodworking switch pointed out at the beginning of the thread

 

[Mike Johnson]

Can't find any reference to an NVR at the beginning of the thread, can you post a link?

 

[mainline]

Can't find any reference to an NVR at the beginning of the thread, can you post a link?

Its not nvr but looked the same at first glance #13

 

[Mike Johnson]

An NVR has an additional level of protection, and that link is to a unit that is not available, so not much use to the OP.

 

[mainline]

An NVR has an additional level of protection, and that link is to a unit that is not available, so not much use to the OP.

It was in relation to does a 20 amp stop switch exist.

If you want to be picky the op has completed the job, so you're a bit late also yours isn't rated at 20 amp anyway so not what he asked for.

We don't know what the circuit was intended for, so a NVR may not have been suitable anyway as it may have been wanted for a fan cooling system for instance and would have needed to come back on after a loss of power.

 

[timhoward]

But it seems to be OK for someone else to then give misinformation and say that a mcb is fine for isolation when it clearly isn't without knowing the circuit.

Isn't it equally misinformation to say that an MCB isn't fine for isolation without knowing the circumstances?!
In my world it doesn't seem totally ridiculous to suggest that
a) you might turn a circuit off before you work on it
b) you might not expect there to be two supplies
c) it would be better if you only had to turn one circuit off.

That's the point, surely?! We both know and understand that MCB's are often single pole, and the principles of isolation. I think that labouring this only distracts from the point I was trying to make.
Granted, if we just threw the double pole main switch my point become irrelevant but in the real world circuits often get worked on with other circuits live.

 

[mainline]

Isn't it equally misinformation to say that an MCB isn't fine for isolation without knowing the circumstances?!
In my world it doesn't seem totally ridiculous to suggest that
a) you might turn a circuit off before you work on it
b) you might not expect there to be two supplies
c) it would be better if you only had to turn one circuit off.

That's the point, surely?! We both know and understand that MCB's are often single pole, and the principles of isolation. I think that labouring this only distracts from the point I was trying to make.
Granted, if we just threw the double pole main switch my point become irrelevant but in the real world circuits often get worked on with other circuits live.

Tim
I agree and am not having a go at you, but some seem to have had a go at me for simply passing on information that an op has asked for without asking the right questions and then being accused of not having the knowledge of being able to give the correct answer even to the point where it could kill people.

Yes, in hindsight maybe I should have asked the relevant questions then this thread wouldn't have been so long but there again ?.

I hope someone doesn't ask a question along the lines of "I need to change a bulb, but it screws in and I don't know what type it is"

Then you ponder in whether to reply e27 or do a full risk assessment of how high or what type of steps they have etc before answering their question or just not bother at all

 

[timhoward]

@mainline - all ok! I had misinterpreted/misunderstood your sarcasm earlier. I believe we are in agreement on most things including disliking the unfortunate way this thread developed.

 

[mainline]

@mainline - all ok! I had misinterpreted/misunderstood your sarcasm earlier. I believe we are in agreement on most things including disliking the unfortunate way this thread developed.

Me sarcastic ? Never

 

[Spoon]

I hope someone doesn't ask a question along the lines of "I need to change a bulb, but it screws in and I don't know what type it is"

Then you ponder in whether to reply e27 or do a full risk assessment of how high or what type of steps they have etc before answering their question or just not bother at all

That is very funny. I've been laughing all day.
I thank God I wore my corset for fear my sides may split!

 

[mainline]

That is very funny. I've been laughing all day.
I thank God I wore my corset for fear my sides may split!

There are risks in wearing a corset/waist trainer, you would be well advised on having a good read up as you could do some serious harm or maybe even kill people, it could be that you drive a coach for instance in-between jobs (of course we don't know that because we haven't all the information to hand) but flaking out at the wheel because of your corset being tight could result in catastrophic consequences.

What happens if your corset is too tight?


Women/Spoon were often laced, so tightly their breathing was restricted, leading to faintness. Compressing the abdominal organs could cause poor digestion, and over time the back muscles could atrophy. In fact, long term tight lacing led to the rib cage becoming deformed.

 

[Ray Pooley]

I’ve been asked to provide an emergency stop button for a circuit rated at 20amps. I’ve never installed one before and only really found 10amp buttons at my local wholesaler. I can put a contactor in, no problem but was just interested to see if you can get them?

Whatever it is you are trying to isolate in an emergency the 20A spec is a minimum. Anything above that should do.