I am working as a project inspector for a large project in the San Francisco Bay Area of Califonia. The electrical contractor has supported the EMT conduit and boxes utilizing screws with plastic inserts into the drywall. In my 20+ years as an inspector, I have always required that these supports be into a framing member rather than the drywall. When asked to correct the problem, the contractor indicated that NEC Article 348-12 only requires that the EMT be "securely fastened into place", and that per NEC Article 370-23 the boxes may be "fastened to the surface upon which they are mounted unless the surface does not provide "adequate support". He feels that the drywall with plastic inserts meet these criteria. I disagree. Does anyone have an opinion on this subject, or advice on how to get the contractor to support these items from the framing members.

I don't trust those little plastic slugs for drywall!

They're tricky to install and eventually they wind up chewing up the hole they are stuck in to the point of falling out - no friction!! I've had that happen many times (thank god I don't live in one of those cardboard boxes anymore (gypsum board is another issue entirely, I've always preferred metal mesh & cement and plaster interior walls).

They also have no gripping power, so if you use these to mount an outlet box, you'll be sure to see that box dangling from the pipe after repeated plugging and unplugging appliances from that socket.

Maybe those metal inserts - with the wings that bend back against the side of the plasterboard facing the studs would work better (I believe they're called toggle bolts) as you tighten the screw?

Although who knows how good they are for holding up conduit and boxes...definitely a step up above those plastic inserts you mention.

Just my humble opinion.

MG, here is a link to a manufacturer of those anchors. They come in plastic as well as metal. They have a better type, that is a combination of the metal screw-in anchor with the addition of a toggle. The web page has a "Pullout" and "Shear" chart for the anchors. http://www.itwbuildex.com/ezprod.htm

Just tell him that you don't believe that those plastic ancors provide adequit support, suggest the use of the metal screw in type anchor in the future.

They work very well, though expensive, you screw in the anchor and then a regular screw screws into the anchor. I've used them to secure many things, including pvc, emt, picture frames, surface mount boxes (exit lighting applications), sometimes they help in addition to a few screws in the framing members, i've used to them to secure part of a panelboard that would have otherwise been able to move 1/4" on one edge because there wasn't a framing member, although the panel would not have fallen down and was adequitely mounted, the extra security of these devices helped.

Plastic plugs are crap for drywall, they're only useful in concrete, even then, it's touch and go

Oops, I thought the contractor was using the plastic screw-in ones. I didn't even think about the plastic expanding anchors.

Is there specs for this job? If so then you have to enforce what the engineer spec'd out.

On a job I was on we had an inspector tear a box off the wall (using those plastic anchors)...he said it didn't appear very secure to him!...guess he didn't like plastic anchors.(not my work, thank you)....when the electrician started to complain he opened his briefcase showed us his very dog-eared mechanical, electrical, plumbing, and building code books and proceeded to show us about a dozen microscopic code violations in all the trades...he assured us he wasn't there to nit-pick us and wouldn't bother us with citing us and charging for a reinspection, however he was sure we agreed with his 'poor securing' position for the elect. box. !! I had to bite my tongue to stop from laughing.

If the anchors have a load rating in drywall, I guess you could compare the load rating to the actual loading. (Pull out is perhaps the mode of failure not gravity loads.)

If the anchors lack a load rating, fail the job if you wish.

Thank you for your comments. I came across a good publication in the NECA 1-2000, "Good Workmanship in Electrical Contracting" which was referenced in my specifications. The project specifications indicate that the conduit and junction boxes shall be supported in accordance with good industry practice. NECA 1-2000 indicates that the "supports shall be adequately attached to the building structure or structural member." In the Junction and pull boxes section of this publication, it states "Junction and pull boxes shall be firmly and securely fastened to or supported from the building structure or structural member." I think based upon this standard of workmanship publication, I will go back and require the contractor to properly support the conduit and junction boxes to the sturcture or structural members on this project.

Thanks for sharing your experience. I have a question about EMT conduits. If I install EMT conduits in my office, what do we need? A friend said you should contact tinktube. Should we do to contact him or not? If you have any other ideas, please let me know.

The key is to remember codes define “barely good enough.” Codes are not meant to define “best” or plan for every situation. (This has a corollary: Those who cleverly seek out “code minimum” are ignoring their duty to build for the job — not the code).

I’ve mounted miles of EMT and thousands of boxes on drywall using those plastic anchors. Until recently I had no cause to question the practice. Then I moved to Arkansas.
The local combination of aged drywall and constant humidity has resulted in anchors easily pulling free after about ten years. Unsatisfactory by MY standards, especially if there is anything heavier than a small picture hanging from the anchors.

Of greater concern to me is the part of the code with the vague requirement that wires be protected from mechanical and environmental damage. This can mean that there is no method that is acceptable— by my standards, at least. (My position has made me most unwelcome at some locations).
Back on point: IMO box placement is the first concern with the anchoring method chosen to suit. Not all drywall is the same (some is designed to be stronger, harder, and more moisture resistant than other varieties) and not every anchor faces the same loads. For example, a box with a light switch won’t see the same loads as one with hospital grade plugs in it.

The most common method is to have the carpenter place wood behind the wall; long screws get the job done.

“Good practice” aside, I hold that determining anchoring methods and box placement is outside the scope of the code. Most relevant code language is unenforceable. You’re an inspector and not a king.