What you need to consider is what potential injury could be caused by the motor or any of it's connected parts, if for example the motor was driving a pump & the interlink connection was shielded there is little possibility of these causing injury i.e. no moving parts exposed, however, other possibilities are fractured pipe causing a corrosive liquid to be sprayed if you see what I mean then the risk assesment should highlight the possibilities of injury or death.
Just because there are mechanical moving parts it depends on what these are, a motor in itself is not usually considered a danger, what it is driving could be.
As the purpose of opening the container would be for maintenance only then perhaps the following would apply.
Engineer access only ( could be a procedure where only engineering have access to the key, this to be signed out when required, training & warning signs). Again, would need some form of identifiable way of isolation of equipment i.e. lockout, local isolator or complete power down & lockout once access has been granted if the plant is to be worked on.
In your case, it appears that your concern is the motor or what it is driving, you need to consider all equipment within the cabinet & the cabinet itself.
Would it be a confined space, in that case there needs to be a procedure for entry regardless of other factors like isolation, possible chemical or afixiation dangers, trapping the list goes on.
On our systems that had large cooking vessels, there was a procedure, this was for entry into confined spaces should an engineer need to enter the vessel.
1. Entry permit issued (only to trained engineers)
2. Complete isolation of the plant i.e. panel locked out, motors isolated & locked off, steam & feed services locked off.
3. Safety harness & extract rope for person entering vessel.
4. 3 men (2 to initiate egress of person in vessel if required).
5. sign off & return of lock off keys.
So. just sticking an isolator on a motor although great for maintenance purposes is fine, but as a combined system there are other factors to consider, should an engineer has access on his own, consider an accident, perhaps a minimum of 2 persons at location if remote.
Some years ago, I did a comprehensive course run by Pilz, so although now not kept up to the latest legislation etc. it opened my mind, the current legislation lke machinery directive & as like most have this saying "As far as reasonably practicable", so it always puts the responsibility on the designer, in some situations it is impossible to "ISOLATE" particular equipment i.e. if it is required to be in operation during maintenance, however, all reasonable steps need to be taken to "Engineer" out the likelyhood of injury etc.
