I've asked this question many times over the years, but have never really gotten a definitive answer. I watch a lot of home improvement and real estate shows. In every instance where the show is set in the Chicago area, the receptacles are always mounted horizontally. Personally, I think that this looks pretty awkward, especially in kitchens where the switches are mounted vertically next to them along counters.
Also, all wiring is done in EMT, even in residential construction. The place can be 100% wood framing and full of PVC plumbing, yet the electrical work is always done in EMT. I would imagine that this requirement causes the electrical costs to skyrocket in a competitive construction market. Don't get me wrong, I am a huge fan of EMT installations, but isn't this quite a bit of overkill?
My guess for the horizontal receptacles is due to the fact that EMT is run horizontally between outlets and by placing the mud ring sideways, it makes it easier to pull the wire in. Again, that's just my guess.
Does anyone know anything about this? Is this just "local practice" or is there really some awkward local code that requires EMT in residences? If so, why?
I noticed last night on a show that took place in Hawaii that the same thing applied. All receptacles were mounted horizontally. Granted, all three condos were in high-rises, so I suppose that this could have been due to the fact that the place was wired with EMT as well. At the same time, I've been in hundreds of high-rise buildings in other parts of the country, both residential and commercial, and have never seen installations such as these required.
Perhaps my most perplexing question is how home improvement stores handle the Chicago requirements. Is it possible to go to a Home Depot in Chicago and buy a roll of 12/2 Romex and a case of plastic boxes? Have the forces that mandate 100% EMT been able to restrict the sale of non-approved wiring materials? Will the Union people stake out the joint and beat up anyone who comes out the door with Romex? I just can't see a Harry Homeowner running EMT or Greenfield to install a ceiling fan in a bedroom, so with that being said, do they even try to do their own work?
Sorry for all of the questions, but this stuff just makes no sense to me after thirty+ years in the business.
