Requirements for contractors Hi,
I used to work as a project engineer before I got into H&S. It was a while ago but we also used to write project standards, part of which included referencing the required legislative standards and added 'and any other relevant national or regional standards'. It is great that you are thinking of setting company standards over and above the relevant legislative standards. Your mechanical notes do seem to reflect some of the ASNZS 4024 1801 standard though. FYI the ASNZS 4024 1204 is the elctrical equivalent. We did specify electrical cabinet rating depending on the environment, for example, IP65 for dusty environments however, I think that may now be covered in more recent standards but am not sure. I am also 99% sure there are standards around sheathing of wiring as well. Another thing we used to specify was labelling of all wiring and breakers etc in electrical cabinets. Fault finding in complex machinery where the wiring isn't labeled is definately not fun speaking from experience, and is extremely time consuming.
My suggestion would be to look what the different applicable standards are over and above the legislated standards so that you are not doubling up and note them in your company standards as well, as not all standards are incorporated into law i.e. if you don't specify them then the contractor/supplier does not need to comply with them. I would also specify that 'sign off by a registered engineer confirming compliance to the relevant standards and legislation is required' at various stages possibly depending on the size of the job. You may or may not want to follow the PS1 to PS4 process with smaller jobs.
I don't know if that was helpful or not, you probably already have a lot of this in your projects standards anyway but thought I would mention.
It also sounds like some contractors may need to be held to account more for their works and I don't see any reason why the local contractors on the smaller jobs shouldn't be held to the same project standards. I know it is always a battle with the smaller contractors who are not used to working with project standards but as you have noted, safety suffers if they don't meet the standards you require.
I hope this was a little helpful anyway.