Potential hazard or not?

[normanton]

We've had a safety memo sent out to us all today regarding a new type of compressor we are using.
In a nutshell, its single phase, ran off a plug top to a rotary isolator on the unit. The L/N/E all go through the isolator, so.. when you switch off the isolator, you're switching the L,N AND E.
The H&S have identified a potential hazard where 'this wiring could lead to a potential electric shock, if the unit develops a fault in the wiring between the main plug socket and the unit mains isolator, if the mains isolator switch is OFF'.

Forgive my stupidity (or maybe not), but I fail to see how this could cause an electric shock if the mains isolator is OFF. The only issue I can see is, if the rotary isolators L2 contact (where the Earth is connected into) for whatever reason failed/burnt out etc, and L1 (Live) and L3 (Neutral) were fine, you could have a situation where you have no earth to the compressor at all. Which of course is an issue.

I may be reading this wrong, or they may have made an error.. Suggestions open.....

 

[snowhead]

H & S are right, for the wrong reason.
The potential issue is switching the Earth between the isolator and the compressor.

 

[Darkwood]

Consider the isolator is faulty and in the off position still maintains a L feed only due to mechanical failure, you have effectively put a feed to a unit and disconnected the earth, also in such set up, the N would float at 230v which heightens the risk of shock to a user, another scenario would be water ingress to a isolator in the off position could track to the load without an earth... there are many examples and scenarios as to why this is dangerous and why regulations do not allow it.

 

[ipf]

It's foolish, who installed it?
Just create a permanent earth connection in the rotary switch.

 

[Deleted member 105166]

Also, the capacitor/s within the compressor may remain energised after the CPC is isolated, the appliance is Class 1 therefore depends on the CPC else in a fault condition a shock may result from touching the casing.

 

[telectrix]

agree with #2,#3,#4#, and #5.