Discuss Does a 20amp emergency stop button exist? in the UK Electrical Forum area at ElectriciansForums.net
That's what the op did, he said he basically just wanted to know if a 20 amp stop switch existed, as he couldn't find one.
I get the questions being asked concerning a risk assessment, but the op a number of times said that he just wanted to know if one existed and wasn't interested in anything else.
Dear mainline,I worked in electronics and programming for over 40 yrs before semi retirement and now work to suit mostly repairing various radio test equipment from all over the world, for 3 days a week i look after 21 cottages on a holiday complex mostly electrical.
Things like this but now more as a hobby
Thanks for the kind wordsDear mainline,
I gather Gibsons jigsaw company are looking for a suitable picture to continue their ‘workshop‘ category of puzzles.
Thank you for the great photos of your lab bench. It clearly is a place where work is indeed done.
Regards
Marconi
View attachment 99430
Fair point, however I have never seen a training environment where the "training is wire up this spar pump"
like I said, if the risk assessment deems it suitable then go ahead but i think it is a vital step that both you and the op are missing.
OP, has anybody done a risk assessment and if so, what stop category are you trying to design. also, is a single point of failure likely to bring a risk of significant harm to anybody?
I am done with this for tonight and my final thoughts are Simpley that on the face of it neither @mainline or @j_arney have the information and knowledge required to design a suitable safety system for this project.
Hey
Im back and done the job. In the end I had a 6amp circuit feeding the stop button then the coil and 20 amp circuit supplying a socket via a rotary isolator and contactor.
I hope you have not seen my comments as either negative or condescending.Hey
Im back and done the job. In the end I had a 6amp circuit feeding the stop button then the coil and 20 amp circuit supplying a socket via a rotary isolator and contactor.
So you had a stop button and rotary isolator switching the socket on and off. I was asked to do this for a colleague at one of our sites and have no idea what he intends to do with this system. He’s designed it, he’s an engineer and I haven’t asked any questions. I can totally understand the repercussions from making mistakes in certain working environments and appreciate all the feedback. I’m on this forum to hopefully learn a bit, but sometimes there’s no need for some of the negative/ condescending replies.
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?
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
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 thoughThis 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?
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
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=caac039e86bf11f04a93756c659eea3eI’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?
Yes I get the " I wasn't meaning safe isolation when I said safely isolatedI 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.
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
Its not nvr but looked the same at first glance #13Can't find any reference to an NVR at the beginning of the thread, can you post a link?
It was in relation to does a 20 amp stop switch exist.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.
Isn't it equally misinformation to say that an MCB isn't fine for isolation without knowing the circumstances?!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.
Me sarcastic ? Never@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.
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!
Whatever it is you are trying to isolate in an emergency the 20A spec is a minimum. Anything above that should do.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?
Reply to Does a 20amp emergency stop button exist? in the UK Electrical Forum area at ElectriciansForums.net
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