I was in the paint department at the local “box store” and I noticed how power was supplied to the paint counter. Please note the EMT that drops from a roof truss and terminates in the top of the panel. Ceilings in this type of construction (“tilt-up”) typically have about 23- feet of clearance between the bottoms of the trusses and the floor. As you can see, the conduit lacks any support, and the length of EMT is clearly over ten feet. That makes for two separate violations: too much distance between supports and no support near the termination. Nearby the HVAC guy ran his line by attaching it to the white “pipe” you see coming down. Appearance is deceiving - that is NOT a substantial pipe. What you see is a single small (water?) pipe covered with insulation then wrapped in a plastic jacket. (The second picture shows an air conditioner line set under construction so you can see how the insulation is applied).
Here’s the issue: Due to the design of these buildings there really is no way to properly support such “drops.” My third picture shows some power cords passing through the ceiling of the local polling place. While this manner of dropping cords violates a different part of the NEC (and I probably violated Federal election taking the picture!), the issue is similar. That is, the construction method and building design preclude any practical way to both meet code AND retain the advantages intended by the architect.
In this respect I think the various code writers have chosen to ignore reality and hide behind such platitudes as “listed assemblies” and “authority having jurisdiction.” They address the matter by passing it off to someone else.
I see those things at Home Depot all the time. I assume that is in their design manual. The only legal way would be to bring something structural from the truss to the floor to provide support and without someone making them do it, they won't. I have seen a 2x3x24' stick of "Patio" (the aluminum they make screen cages out of) run for support. It is really pretty easy since they sell the flange for the floor connection and that could be used on top too. I suppose the pendent drops will hinge on the wiring method and how they comply to 315.25, 210.50 etc. Usually it is just an orange cord that is not compliant. Those kinds of violations usually get caught by the fire marshal. I know when they walked around our office they cited a dozen violations. After that I got tasked with keeping the place cleaned up since I was an installation planning rep at the time.
Solutions to the high ceiling issue that the 'good' electricians here use are 20' length of unistrut, 2-1/2" with a floor flange and a suitable attachment at the truss to support the conduit. A few use RGS, although EMT works. Dependent on 'what' is being fed, it could be back-to-back strut.
OK, yes they use a strut splice bar, to make the 23' (or whatever) length as required.
Cord drops are usually a twist lock receptacle at the ceiling, 'kellems' , and a pendent box with a receptacle as required. Costco, and Shop Rite use this method for portable refrigeration equipment or displays.
Edie’s t, a disclaimer: While the sharp eye can identify the location as a Home Depot store, this challenging arrangement is common in many situations: power drops to pre-fab offices on factory floors, cooler banks in supermarkets, and powering portable / seasonal displays are common examples.
Let’s take the last picture first: the polling place. Here there hang numerous ‘drop cords’ from the ceiling. The issue / complication arises from the use of a drop (or suspended) ceiling. You want the cord to drop as straight as possible to your temporary equipment. Maybe the next time you’ll want to place the gear a few feet over. The common solution is to have a coil of cord laying above the ceiling. To drop the cord a tiny notch is made on the edge of the ceiling tile. This practice was pretty explicitly banned in the early 2000’s when we were precluded from passing cords through any sort of partition (Ahem, dishwashers, anyone?) The “compliant” method of mounting a box to the ceiling became questionable when the Code then went on to ban supporting / attaching anything to the suspended ceiling. Good heavens: there are entire product lines of UL-listed components designed for ceiling grids! I wouldn’t know where to find an engineer to certify my “modification” of the ceiling.
Perhaps this is why suspended ceilings became unfashionable, to be replaced by the “open” framing now common to places like Home Depot — a design that presents its own challenges. With the bottom flanges of the roof trusses typically just more than twenty feet up, and the trusses themselves yards apart, constructing any sort of framework quickly become quite the project — even with strut. The “drop” location is often defined by the placement of architectural elements (like the paint counter pictured) or the design of the production machinery served. That’s how industrial locations end up having all manner of pipes on the floor. Do you want to cut a trench in the concrete floor?
Let’s look at another problem: right angles. If you’ve ever used a shower where the curtain wrapped around a corner you’ve seen how weak that structure is. We create the same issue when we cantilever pipe off a rafter then turn it ninety degrees to drop to the floor. The result may look pretty, but has all the strength of a wet noodle.
Finally, we look at the elephant in the room: inspection. These issues are often found on the various modifications that take place after the inspector has left and the permit closed. There are no inspections.
The requirement that things not be supported by suspended ceilings has been around since the 90s anyway. I know we had to go around and add additional wires to troffers when I was still at IBM. There are a number of solutions but they are all basically just adding another wire or two to anything attached to the grid. I think I could work with the installers to come up with a compliant resolution and in an industrial looking place like Home Depot, they would usually be OK with it. Bed Bath and Beyond? Maybe not
Solutions for the drop ceiling type issue that have come up at various jobs, that had permits and inspections:
Bar box to ceiling grid, support wire to framing, twistlock receptacle in box facing down, suitable cord w/twistlock male cap, and 'whatever on 'load' end. When equipment was placed, it was plug & play.
Installing a cord reel. Yes, it's ugly, but in certain places, it works.
With the open ceiling issue, dependent on the height, using RGS to the compliant limit of 20' secured on both ends works.
HotLine, the suspended ceiling issue is complicated by one detail: next week they may want the item served by the cord moved over ten feet - or more. Think of the “hot tables” found near the registers at tour local market. Today that cart might be parked by register #3; tomorrow they might want it over by register #7. Wherever they park it, they want the cord to neatly drop as plumb as possible. They’re not going to want a separate cord drop at every tile. The issue arises where the cord passes through the tile. I understand the codes’ concern about abrasion. Yet I fail to see how a ceiling tile can abrade anything. I also note the universal practice of passing a dishwasher cord through a hole in the side of the kitchen cabinet — without a peep from anyone. Use a bushing? Code makes no such allowance. I simply says cords can’t pass through.
The new houses I saw my wife building had a split receptacle under the sink for the dishwasher and the disposal. There was a pretty big bushed hole for the water and power and I never heard anyone say that was an illegal pass through of a partition.
I agree if they want to have cord drops in a lot of different places it might be a challenge. My bet is it will end up being non-compliant and try to slip through the "temporary wiring" loophole. My real life experience is it will be an orange cord and "come and get me copper".
The issue arises where the cord passes through the tile.... I simply says cords can’t pass through.
Under the "Uses not Permitted" it clearly says running the cord through a hole in a suspended ceiling tile is not permitted. Further down it says that cord is not to be concealed by a suspended ceiling.
