Hi Shelley

The relevant part of the definition of "construction work" in CDM 2015 is:

(e) the installation, commissioning, maintenance, repair or removal of mechanical,electrical, gas, compressed air, hydraulic, telecommunications, computer or similarservices which are normally fixed within or to a structure,

Which then takes you to the definition of the final word "structure".

The definition of "construction work" in CDM is largely a cut and paste from the definitions os "building operation" and "work of engineering construction" in Section 176 of the Factories Act 1961, so the case law on what WAS a "building operation" is likely to considered authoritative by the Courts when they come to intrepret what IS "construction work".

That case law said that the "vessel" which you refer to is almost certainly NOT a "structure" within the meaning of CDM 2015.

However that vessel is probably within a building which definitely falls within the definition and paragraph (e) talks about services within a structure.

So, given that one of the rules of legal interpretation is to take the wording literally I would suggest that installing these services would be "construction work".

You have two legal people who fall within the CDM definition of "contractor" - you and your electrical subbie.

So, on that basis I think you need a PD and a PC whether or not the project is notifiable.

However, CDM doesn't ask you to complicate things.

What would you differently in terms of managing this work if you DON'T apply CDM? Surely you would still have a process to control access to where the work is being done, to choose a suitable electrical subbie and to control them, including e.g. checking their risk assessment documentation and doing some monitoring of how they perform?

That would be the basis of your "construction phase plan" and some of the documents coming out of the project go into the "health and safety file" for the site (or part of the site).