Personally, I would be doing everything in my power to prevent lone working in an engineering workshop.
I would not allow my employees to do it when I had such a place.
I have my own workshop now, & I HATE having to work there alone, I am very on edge and super careful.
I don't believe that lone worker alarms would be adequate.
Death from electric shock comes very quickly and you need someone competent to sort that out lest they become another casualty.
The victim would quite possibly be incapacitated from the electric shock, and unable to activate the alarm, there is also the possibility that they would come to rest in such a position that the alarm may delay its activation for just too long.
Also, death from loss of blood from serious laceration injuries comes quickly.
The affect on a victim of such an injury could be such a level of shock that they could be incapacitated and unable to activate the alarm.
Both of these scenarios are possibilities and there is the potential that a lone worker alarm would not be fast enough, if it relied on the prostrate or not moving mechanism.
Also, you have the possibility of false alarms, what if thee operative has to lay on the floor to undertake works, and stops still for a little while to think about the task at hand laid flat on their back?
I've done this too, many times, laying flat on a cold concrete floor to think about the job has a funny way of focussing your thoughts to get the job done and get off the cold floor somewhere warm!
Then there is the possibility of intruders?
Do you have Oxy-Acetylene? Marvellous tool, much maligned and too many people are afraid of it.
Mind it seems that the FRS have had some research done, and it’s not considered as bad as it was.
However, that is an aside, my point is if an issue with any oxy-fuel gas cutting and welding equipment were to occur when there was a single operative deeply engrossed in their welding/cutting work, then this could go un-noticed until it was such an issue that it could be a total loss situation.
I KNOW of a large upmarket car dealership that was a total loss because of a fire, OK, not oxy-fuel gas, but, if the nearest person to the origin of the fire had acted promptly and correctly, then the fire would have been prevented.
I also have a personal friend who very often works in his engineering workshop on his own. He is self-employed. A few months ago he called in to see us at home, he was a bit stiff moving around, we thought it was his age, he is around 70, but still working so we did think it unusual.
We enquired as to what had happened.
It transpires he was working late in the workshop one evening a few weeks before.
Nothing unusual in that, his family are used to it.
He got his overalls caught in a large horizontal milling machine.
The machine picked him up off the floor by his overalls and spun him around the spindle 7 times before he could stop the machine.
He then had to extricate himself from the tangled mess.
Luckily he had NO serious lacerations, very bad bruising, and nothing broken, very sore and stiff for a few months mind.
This guy has been doing this all his life.
Now I’m not saying that he was being careless, and I’m not saying that he is as safety conscious as he perhaps could or should be.
BTW, he knows it was 7 times as that was the number of times the lights flashed in front of his eyes as he thought that he was going to die (the lights in the roof of the workshop). His words, probably not his exact words, as I would get moderated if I used them!
He is fine now and still working.
I always bring these two examples up these days when I discuss lone working in engineering.
IMHO, not a good plan.
HTH