Not all jobs work that way. The mechanical contractors on our projects don't supply the pumps, chillers, cooling towers, air handlers, dehumidifiers, air compressors or water filter systems but they install them. That is what they bid on when they bid the job. On some jobs, they don't supply a lot of the piping specialties either.
This isn't done to take profit away from them. It's done to maintain control of the project on behalf of the owner. We specialize in utility systems for the particular industry where we do most of our work. We know what works, what works together well and what tends to create problems during installation and down the road for the owner. We sell the owner a function, not a bag of equipment. To guarantee that function, we maintain control of what specific components go into the system. There's very little back and forth and consequent delays during the construction phase of the project due to requests from the installing contractors to substitue some other brand or model for this component or that one. The jobs get done faster and end up working exactly as we intended.
The electrical portion of the project is similar but, because of all the industry and code standards involved in electrical components, the EC generally provides a lot more of the hardware. Sometimes the owner has a brand or other preference that is enforced but otherwise the decision as to what brand name to use is left up to the contractor. That is sometimes not true of big items like main switchgear and large transformers which are more subject to owner preference. But sometimes owner preference reaches down to details at a very low level - what brand of selector switches or disconnect switches are allowed for example. In the end, the owner is paying the bills and gets to decide how they want the purchasing done. Both we and the owners are aware that some contractors are put off by the practice of owner supplied equipment. Some choose not to bid on the project because of that but mostly not. There's still a lot of work to be done and a lot of materials to be supplied.
Project documents make clear at the time of bid what equipment is going to be supplied by the owner. They also make clear that the contractor's scope of work includes complete installation of the equipment to a ready to operate state. Specific exceptions to that are made clear such as factory commissioning of chillers and large air compressors and specialized production equipment. In general, if warranty terms require commissioning by factory technicians, then that's what happens. In some cases, commissioning may not be required by the factory for warranty but is so specialized that it's performed by them (or by us) anyway.
Electrical switchgear doesn't, or at least hasn't, ever fallen into either of those categories. The contractor isn't expected to take responsibility for the function of the gear beyond that which is dependent on the installation but that doesn't mean he shouldn't perform functional tests and adjustments that can only be done after the equipment is installed, wired and energized. If he believes he is being asked to do something that he did not include in his bid or that isn't included in the contract, he is certainly welcome to speak up but that hasn't happened in this case. He says he isn't sure what needs to be done. I don't think an installing EC has ever told us that before.
