This I believe was a typical residential service where the new panel was going to be in a new location. The contractor wanted to know if could use the existing neutral terminal and run one larger conductor from the old panel (which is now going to be gutted and used as a j-box) to the new panel, while carrying the hots for each of the existing circuits back to the new panel using separate conductors.
FYI-conduit is required in our municipality so separate cable runs are not a concern.
I think you changed the topic, but just in case there is a correlation I missed...
Chicago is a strong union, steel manufacturing city. Fire statistics are supposedly low from electrical installations. (Not that I trust anyone's stats.) To answer your question, I doubt you'll see it unless a horribly corrupt union starts turning out unqualified electricians and problems start occuring.
I personally like the requirement because emt is a higher standard of installation than any type of cable. Additional circuit can be readily added or repaired or replaced with much less cost in the future.
EMT as an equipment grounding conductor is much more reliable than a wire over the long term life of an electrical system. Even BX that was allowed to be installed in Oak Park in the past is in many cases discovered with loose or disconnected connections. I see it every day. I constantly have to tell the electricians to tighten and secure BX connections that were "existing", when the back of bathroom, kitchen etc. walls get opened for a remodel.
I see much less old black pipe with loose connections. Also the walls did not have to get ripped open to replace the old cloth wiring.
If Romex was allowed, in my opinion, the number of non-code compliant, and severly dangerous installations would increase drastically in a period of 5 to 10 years.
I have worked in FL for a period of four years. The problems with electrical installations I saw in FL were more dangerous and much more costly to repair.
Of course, I grew up in Chicago and may have a biased opinion. Then again I may be completely objective.
Problem? Higher standards than the NEC is not a problem.
To date there have been almost 1200 electrical permits pulled this year alone in Oak Park. Oak Park has a population of about 60,000 and about 14,000 addresses. Having to run emt has not caused any type of slow down in construction.