Can anyone provide me with any regualtory guidance on the use of drop cords in an industrial setting. I have a facility that has almost all of their equipment/machines running off of heavy duty electrical cords which hang down from the ceiling. They even have some cords that have outlet boxes attached to the ends for use in regular table-top appliances.
I come from the school that anything over 90 days is defined as "permanent" and is to be "hard-wired" in conduit with a disconnect means near-by. Their argument for this is, they are always moving equipment around for efficiency and thus use the cords.
I'm sure there are those who will argue this is a code violation and cite code sections.
However, this is a very common commercial/industrial practice because of the reasons you just gave...machinery moves around...equipment is in the middle of the floor (of a 20,000 s.f. room)...it is common to run conduit over the ceiling, use SO cord with a strain relief at each end and terminate in a box ([400-7(a)(1)]says pendants are allowed). A building I've worked on for over 10 yrs. has these in the warehouse and production areas - the inspector has never challenged the installation.
P.S. (re: Joe's comment) - I've only seen this approved when using boxes with a threaded entry (like the Killark FS boxes), no KO's.
[This message has been edited by dana1028 (edited 07-24-2003).]
Here's the rule in the 2002 NEC that prohibits a box with knockouts to be used in the manner described. OSHA would also cite them because of their concern about open knockouts. This has been a long standing rule for a long time!
314.23(H) Pendant Boxes. An enclosure supported by a pendant shall comply with 314.23(H)(1) or (2).
(1) Flexible Cord. A box shall be supported from a multiconductor cord or cable in an approved manner that protects the conductors against strain, such as a strain-relief connector threaded into a box with a hub.
This is a common practice for those places that move equipment around periodicly. Another reason is vibration of the machines. If installed per code and with some sense about length of the cords, it is a safe practice. It does require the maintence people to inspect the cords and connectors frequently.
In industrial manufacturing buildings, such as one I recently wired, where the ceiling is 35', the building measures 460' x 500' and the support columns are 60' OC how else would you provide electrical service to machines and work stations on the floor if you didn't use pendant drops? If you used conduit what would you support it to? Besides, when it snows the roof flexes up to 8" between columns. Stub ups in the concrete floor would eventually encourage the use of extension cords as assembly lines and processes changed requiring the re-arranging of work areas and machinery. Cord drops are the safest way to go when properly installed.
Fred: I understand what you are saying, the intent of what you want a cord drop for, and the limited choices available, as I also am an EC. I have installed many cord drops over the years in industrial/comm applications.
When I have a job that requests cord drops, the first thing that I do is call the local AHJ, and get a determination ASAP. Some areas do not "catch" the cord drops on Plan Review, and it becomes a nightmare after the job starts.
THe AHJ that I referenced above has a "solution" that is NEC compliant in his opinion... RGC and IMC are allowed to be used for "drops", unsupported for a length of xx' ('02 is in the truck again) A suitable support at the roof decking, and a floor flange at the base. A "tee" fitting can be utilized to tap off a box, which requires support. His other acceptable method is aircraft cable for support of cable (MC or ??) with ty-wraps.
The above is an opinion of another AHJ, and the topic has been brought to the County Board of Appeals numerous times, and to date no contractor has succeded in overruling the drop cord ban.
Your points about stub outs and the extension cord useage is understood, and it is a common occurance in many locations around here.
I will invite the AHJ to visit this site again, and enter his opinions if he so desires.
Well we have cord drops in our facility. Not sure that I really like them, but they are useful. For one thing helps for lock out tab out. The one problem with them is when the equipment gets moved a few feet. Then you have a crooked cord hanging down. One of my pet peeves. One of the first things that I did when I started was to buy some string and tied a 1/2" nut on the end of it. Boys, here is you plumb bob, use it!
However if a drop is going to have an outlet box on the end of it we hard plumb it and attatch the box to a uni-strut stand.
BTW, we have had many OSHA inspections. We used to call them in voluntarily. The only comment about the drops was to make sure they have a strain releif attached at the ceiling.
Oh yeah, being in CA we do have earthquakes here and they help if the machines should walk during an earthquake. Scott