On new homes I have seen Romex run thru same holes the plumbers use for their Pex tubing (Red & Blue Plastic). Is this a common thing to do? Sometimes the plumbers drill 2" or 3" holes thru these laminated I beams, there is plenty of space around the pipes for Romex to go thru, but is it wise? I always drill separate holes for my Romex or use the prepunched holes. Just wondering!

Nothing wrong with that unless the tubing is for hot water. I prefer not to do it either but this can actually be good since too many holes in these things will reduce their load bearing capacity.

-Hal

I just do not do it .It is a very un- workmanlike manner. I drill the holes.

been red flagged on it , in new jersey by local insp. i do not use the same holes as them anymore.

Ran EMT through a plumbing hole once, due to no other space available. Didn't get red-tagged, but was strongly discouraged by the AHJ from doing it in the future.

Besides local prohibitions on NM, if it was allowed, I doubt we could "share" with anybody, given the climate around here (Chicago metro)

By sharing the holes, you may subject the NM cable to abuse and stresses. It may not be strictly forbidden, but it is not a good practice.
I wish I could say I have never done it myself. I can say I never was proud of the jobs where I had to do it. (Sometimes your boss, or even the general contractor, has the last word on the quality of the job we do.) Oh, well.
Most of the work that gets installed out there never gets inspected. We are the first and last inspector of our own work.
Have you ever hit a staple too hard and damaged the sheathing? Did you then remove that section of NM and replace it? Or did you merely tape it, or worse, ignored it?

No matter what we think of it I do not know what code section could be used to fail this.

Perhaps the inspector could say it is subject to physical damage?

Bob