Depends on the risk of someone else turning it back on inadvertantly - without knowing the machine difficult to say (location of stop etc) - but this has been the cause of a number of fatalities over the years. Remeber E stops are what they say - they should not be used as the ordinary way of turning the machine off .

The use of E-stop was common in an overseas operation until a day the operative was well within the machine. Not seeing anyone present and an idle production line the supervisor presumed the line had stopped whilst the operative had gone for a comfort break promptly re-started the line and immediately killed the worker.

US head office sent teams to train Lock Out Tag Out methodology globally.

In the UK we were used to having Castell keys on the lines power supply - if an operative wanted to enter the danger zones the power was isolated by taking the key and opening a relevant access gate using that same key.

We had to apply an additional operator (single key) pad-lock to keep the power key point cover closed to counter the possibility the gate could be closed and the operator Castell key returned to the power switch whilst the operative remained inside the machine.

In this scenario, I don't understand the justification that there is no risk of someone else turning the machine back on.  What exactly stops someone else from doing this?

I think you may have got your terms mixed up here...functional safety is the design safety requirements for the not the premis for isolation  - functional safety is the workings of an emergency stop for example or a light curtain - all in compliance with 13849/ 62061...the use of that to isolate the machine is the same as using the e-stop..which as we know shouldn't be done... 

"As a general comment, why do people spend so long trying to justify what they know isn't right, just because operators or managers don't like the required controls?"

Isn't that against at least the spirit of IOSH rules? 

I agree with Paul above it depends on the complexity of the machine and how automatic it is. The OP talks of tooling change or a setting change. If the machine was say on the less complex side such as a pillar drill then to change the drill bit you would just turn it off as normal and using the E stop or LOTO not required. The operator would be next to the machine and the controls, and I could see no reason that someone would lean over their shoulder and turn it on while the operative has their hands on the chuck /bit.

The other end of the spectrum is some automatic machine with a remotely positioned control that would kill you as soon as look at you given half a chance, that someone else could think should be on. Then there is a whole spectrum in between of machine and controls. A CNC milling machine with interlocked doors, where the machine will not operate when the doors are open to allow removal / insertion of the workpiece, would also allow for changing a damaged / blunt cutter in a carousel perhaps or even just a replaceable carbide tip.

Without seeing the equipment, it is not really possible to comment on the OP’s question IMHO

Chris

I read it the same way, I too thought the criticism was that the comment was offensive to a fellow professional!

Firstly, Jeppers, your first posting on these Forums, so welcome.

I think that this thread has veered to the extent where if we had an effective Moderating team, part or all of the thread might have been taken down while some parts were resolved.

I thought about multiple messages via the PM facility but it would take too long.

We have to remember that these are the Public Forums open to people who are NOT members of IOSH (and whilst I see that Jeppers' profile indicates that they are a Member, we don't know what grade or background they have) and so I am not sure that quoting the Code of Conduct is particularly helpful and could easily deter a new visitor from the Forums.

As I see it the original question can be read as looking for informed answers to a reasonable question and NOT looking for an excuse to break some sort of clear rule.

LOTO is not mentioned in UK law and is a non-native invasive species like the American red squirrel or Spanish bluebell. I think that the first time I had every heard the term was probably about 15 years into my career in H&S.

If we look at e.g. the Electricity at Work Regulations 1989 or its predecessor the Electricity (Special Regulations) 1908 as amended in 1944 they don't talk about locking off but rather that work on equipment should be done "dead" unless there are good reasons to do "live" working.

There are lots of machines where LOTO would simply be impossible for the simple reason that there is nowhere to lock off - most things that get plugged into a socket. So whether doing electrical work or other maintenance the usual practice would be for the person doing the work to unplug the machine and be the one who makes sure that it's not plugged back in until all the covers are back in place. 

To ensure an adequate level of safety they might do things like put a barrier around to alert others, but if you bring in an engineer to sort out your washing machine at home, this is very unlikely. 

Then various comments on this thread do illustrate why some work on machines may be permissible with guards open but without isolation - much being down to the nature of the equipment and where anyone at risk may be compared to where the means of restarting is, or where the machine may restart by itself.

So, Jeppers, I think the answer to your question is "it depends", followed by the usual get out clause "and depends on what your risk assessment concludes is appropriate" to ensure safety so far as practicable or so far as reasonably practicable [depending on which specific legislative requirement you are considering].

This question would possibly be easier in the US. OSHA Regulations would probably dictate LOTO. But in the UK it's about working out what to do to comply with the letter of the law and its aims in goal-setting legislation.

BUT, the accident statistics are very clear - the almost entirely prescriptive and proscriptive requirements of OSHA Regulations achieve less than the qualified duties in UK law.

Edited by user 17 May 2022 15:57:17(UTC)  | Reason: Typo

yes I get it and , well to be pedantic you are...functional safety isn't that - the manufacturers guidance in your example for changing parts includes the isolations and guidance that is just the operation of the machine...

the functional safety is the failure rate and assessment of the controls and interlocks that provide that machine to function safety and give the manufacturer the information to be able put that on the market safely...in line with 13849 etc 

you can't rely on those for isolation otherwise we would be using e-stops all the time :)  

I am sure somone will pop up a google example that contradicts that but generally speaking that is how we should separate it...at least that is how I have awlays explained it