Risk Assessment

[CEDEng]

If any of you are experts at "Risk Assessment" can you tell me how to arrive at a number for the maintenance man?

I generally thought the R.A. was for "normal operation" but now I'm being directed to add safety features to the cabinet/enclosure doors because there
was a risk there. Obviously there's a risk. The door is interlocked.

The interlock is not a safety circuit (in the technical sense) because duel redundant forced action contacts and so forth are not applicable to my disconnect being interlocked. They ARE applicable in the "risk assessment" beyond a certain level...which, apparently, the maintenance man can reach.

Question, then: How to satisfy a PLx with the enclosure door, since it cannot be monitored...?

I previously thought the Maintenance man fell into the LOTO world.

 

[petersonra]

the risk assessment is wide ranging and covers everyone that may incur risk from the machine. It even includes people who may be walking by in an aisle way. who are otherwise not associated with the machine.

you can chose to mitigate a risk to different people in different ways though.

for instance, you might not allow the operator to enter a confined space because he has not received the proper training for doing so, while allowing some other person who has received that training (like a maint guy) to do so under specified conditions.

 

[CEDEng]

That makes more sense. There are several online risk assessment descriptions that include the words "under normal operation..." and while I can see how that includes someone walking by - the machine is still operating - it would seem to exclude opening up the cabinet doors.

Note that many risk assessment websites do NOT include the words "under normal operation..." so that is just serving to confuse me!

It's hard to believe I've taken classes and received training in this topic and still cannot answer my own questions, let alone other people's!

 

[petersonra]

That makes more sense. There are several online risk assessment descriptions that include the words "under normal operation..." and while I can see how that includes someone walking by - the machine is still operating - it would seem to exclude opening up the cabinet doors.

Note that many risk assessment websites do NOT include the words "under normal operation..." so that is just serving to confuse me!

It's hard to believe I've taken classes and received training in this topic and still cannot answer my own questions, let alone other people's!

my experience with these classes has been that they are usually taught by people who took a similar class not long ago and can mouth the words but really do not have a good grounding in what it actually takes in the real world to eliminate hazards.

 

[gadfly56]

In many ways I see risk assessment as a "voodoo" discipline. The fundamental idea of risk assessment is "what can go wrong", "how likely is it to go wrong", and "who is exposed"? Constructing a fault tree is not too hard and conducting an operational analysis to determine who might be in the vicinity at any given time is pretty doable. The thing that you normally can't get a handle on is "how likely is it to go wrong". Data on how likely a 50-year old man who smokes and is 100 lbs overweight is to die in the next year is the bread and butter for actuaries, but there is little to no data on how complex electrical systems fail catastrophically.