My inspector just turned me down for using sheet rock screws. I screwed up my panel to the studs and mast up the wall. He wrote, can't use sheet rock screws on electrical work. Has anyone ever heard of this? I've been using these screws to screw stuff up for years.

I use galvanized screws to mount a panel to studs, but lag bolts for the mast.

The NEC uses some words such as "secured", with no definition. That leaves it open to the interpretation of the AHJ. Keep life simple...ask wkat you should use in that jurisdiction, and use it.

Dave

We buy galvanized deck screws. They are around the same cost for a box. Drywall screws do snap off too easy. Deck screws are much stronger. The heads can strip out but they don't break. Use them sometimes to hold boxes too.

300-6 Protection against corrosian
Includes support hardware shall be suitable for the enviroment in which they are to be installed.

Drywall screws have a black coating but they do rust. They are not made for outside. Maybe rust thru outside?

To hold up the mast drywall screws are way too weak. Do like Dave said and use lag bolts. Or some other 5/16 or 3/8 fastener depending on surface. Make sure the lags and washers are galvinized. Not that I think they will rust thru. It's just beter to do it in a way that the inspector has nothing bad to say about it. Don't want to do it twice. Besides you don't want there to be rust stains on the house years later because you used the wrong washer.

And don't use drywall screws for fan boxes.

For panels you could also use a #10 anchor swrew (without the plastic anchor). They are tough screws.

An onerhead service should cost you a few bucks in hardware to do a good job.

Tom

sid123456 ---

I believe the inspector is in error.

I don't recall what the strength of drywall screws is but, I expect it is sufficient. You might ask the inspector what load the electrical components need to be desinged to support. I expect you will then have the oportunity to laugh at him.

Sid you said;


This leads me to believe you are talking about an installation exposed to weather.

In my opinion that would be a violation of 300.6


If the drywall screws where not of the galvanized type I think the inspector was correct.

In my opinion the above is clear cut.

The use of drywall screws (even if galvanized) to support a mast is more subject to interpretation.

There are two code articles I can think of relating to mast and this question.


And


The typical drywall screws that come to my mind are fine threaded bugle head #6s.

In my opinion they are to brittle and to thin to be strong enough for a mast, also the threads are to fine to get a good grip on the lumber.

For a mast I would use at least 1/4" galvanized lags.

All this is really up to the inspector to determine the suitable of the fastener for the particular application.

I sometimes use drywall screws to mount 4" square boxes this is a far cry from a mast and I would rather use #10 screws for almost any small equipment.

Bob



[This message has been edited by iwire (edited 04-16-2005).]

I too am a big fan of the #10 Galv/zink hex heads, for most everything, and lags for panels and such.

I can understand the AHJ if his concern was corrosion.

Heard of an inspector failing to pass a job where the sprakies had used drywall screws to secure the boxes. He insisted they install using wood screws.

It was decided that, even though local and national Code didn't specify, it would be easier in the long run to not fight the AHJ, and thus guarantee fewer hassles on future jobs.

I don't see a violation, and I believe the inspector is in error.
That said, I generally do not use sheetrock screws for this application- even though I have many such screws on my truck.
I like to use the screws made by Simpson for their metal brackets. They are of a similar thread and point to sheetrock screws, with two differences:
-they are slightly heavier, at #8 gage; and,
- they have a wider "washer" head, which won't pull through the holes in mounting straps.

For heavier applications, Simpson has also re-invented the lag bolt, giving it a hex (rather than square) head and a sharper point.

I know I sound like an ad....please forgive me....they just happen to make something I like :-)

What about 300.6?

Maybe in Reno screws don't rust out but they sure do here in NE.

http://www.cbs.state.or.us/bcd/pub/tricounty/newsflash/aug_oct_04.pdf

Iwire...you're right, of course....here in the "High Desert" we don't have near the rust problems those of you in the salt belt do. :-)

How long would it take for a drywall screw to rust to the point of breaking in NE.? I can't imagine it would be a concern in my lifetime. I generally use #10 galv. screws but I can't see getting too excited about using drywall screws. My guess is the guy just wan't to find something to whine about.

I was looking through the forum and noticed this topic. I haven’t heard about the “no sheetrock screws” in a long time. Years ago an older electrician (a genius of an electrician at that) that I worked with on occasion told me not to use sheetrock screws because of the metal they were made with. The dissimilar metals between the screws and metal enclosures or boxes would make the area around the hole in the box and the screw rust prematurely and break. How long this would take I don’t know. I just know we couldn’t use sheetrock screws on his projects. Every now and then –such as this post- I hear of this issue and this was the only explanation I was given.

Mic.

It's called "galvanic reaction", and it causes molecules of one metal to migrate to the other, similar to how batteries work. Ever heard of a "sacrificial anode" in a water heater?

http://en.wikipedia.org/wiki/Screw#Tensile_strength

Edward