When is a Design Schematic Proprietary

During field service at a food processor I asked for schematics, was told that due to a “falling out” with the original construction electrical contractor they are not available - management thought they paid for the job, wiring diagrams should be included, contractor says “my property”.

I expect this comes up, must not be searching right as I can’t find much in the threads here. I read about intellectual property/patentability, definition seems something like “not protected if reproducible by others with ordinary skills” (I bet debating that point generates a lot of legal fees).

In this case more than a hundred MCC buckets are interlocked (for lines of conveyors, cleaners, loaders, etc., etc.), will have big material pileups if not sequenced/trip chained. There’s no PLC, just switches, contacts, timers, etc. It’s been possible so far to just take care with wiring (when changing buckets, though PITA if substituting VFD with xline and vice/versa given mix of control volts). I would certainly prefer the big picture though, as I’m finding the interlock doesn’t always follow the physical layout/numbering of the buckets, so things are likely to get mixed up over time . . .

Is this a typical dispute then? I do custom control work myself (smaller scale), always felt obliged to provide an annotated schematic describing the intended operation, with all components and wires labelled (especially since most often me or my guys will be troubleshooting later, nice to have right there in the box). Maybe I’m giving too much away though? I notice here even the factory stuff has unlabeled control wires, guess that costs extra now - pretty frustrating having to identify everything before troubleshooting can begin . . .


This document deficiency issue occurs frequently when the owner drives the acquisition in lieu of hiring an engineer or other 3rd party versed in such matters. They will often neglect to require as-built document deliverables. This problem is almost always the case when software is involved and has been the bane of federal acquisitions, which for the longest time invoked nightmare standards such as DOD 2167 to drive software development and documentation efforts.

You have to ask for the documentation and make delivery of such a condition of approval/acceptance, and you have to specify (in great detail ) what you want.

When dealing with PLCs, the documents should be available by the time you get to the builder trials, so the client or his agent can proof the documents while executing the steps of the trial. Just as you would ask for the builder’s test plan for review and approval, you need to ask for the record documents. If you don’t ask, then you won’t get, and you don’t have a case. Absent such, then you will have to recreate by reverse engineering. Reverse engineering can be a pain, but for critical processes, it may be worth it, particularly if the objective is to ensure continuity of service, repair, replace, etc. In my acquisitions where I supply a one-line or elementary contract guidance drawing, I require the Contractor to supply an as-built drawing, and I may allow the Contractor to satisfy the requirements by re-lining my drawing. Where programming is an issue, he will need to supply maps,etc.

Above is a snippet.