new take on sheet metal screws for panel covers

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reviving in a way, the every popular (16 pages worth) thread from 2010 on using sheet metal screws for panel covers.

I note the winner of the poll on that thread was any short machine screw that fits reasonably (or something to that effect).

One issue I have after reading the comments is that not everyone shares the same definition of machine screw as one of the posts for instance suggest any machine screw as long as you cut off the point. last I looked, machine screws don't have points. that is sheet metal screws.

The majority of panels, in my experience, are designed for a machine screw thread but ship with provided screws are generally similar to that category of machine screws sometimes referred to as thread cutting. these are not tek screws, that self drill and then use a sheet metal style thread to secure in their own drilled hole. these are fine threaded machine screws that taper slightly and may have perpendicular notches in their early threads that provide a slightly 'tap' like crossection.

other panels have machine threads without any real thread cutting device and those boxes have probably been pretapped. They sometimes have a narrower unthreaded lead portion to help locate.

still others use sheet metal style threads with a preblunted tip.

and once accounting for those variations I think I've seen these in thicknesses ranging from 8 - 12 screw or machine sizes.

all of this means there is no standard panel screw, but I'm wondering why it seems impossible to find a selection of various reasonable facsimiles. I would certainly pay handsomely to have something like that because, as another poster in the now famous 2010 thread pointed out, the screws, or some significant portion of them are always lost by the first 3167 people to work on the box.

I get to wonder why I'm always the 3168th person in the box . . . but I have to admit I've lost my share. you always think you are putting them in a safe place -- and I'm sure all these screws are still safe because nobody has ever found them to do them any harm.

I noticed that house inspectors are now in the business of looking for obviously wrong screws on occasion.

in response to those of us who might have voted in the pole for the "why would I put the cover on" option -- which always goes for my own home -- maybe even a sheet metal screw carefully applied is a better option than no cover. obviously you need to pay attention to how the wires are arrayed around the holes and snubbing the end shouldn't be much problem given the availability of highly leveraged cutters in some proximity to the work. Yes you still have a sharper side thread, but that is true of some of the manufacturer supplied screws and care need to be taken regarding the positioning of wires, especially heavy ones near these holes even when using the standard provided screws if plenty of threads on here are to be believed, e.g.

so I'm still looking for an assortment of relevant possibilities because many of the thread types can be gotten but you aren't as likely to get the nice little taper that helps get it in the hole and, as has also been pointed out, it is much harder to come by the head style commonly used - referred to as truss head in the fastener trade.

hopefully I'm positively reigniting a debate here, because this is a constant pain in the butt (hope that satisfies using decent language, i respect the proprietor not wanting this discourse to descend into the gutter) from my perspective.

brian
 

iwire

Moderator
Staff member
Location
Massachusetts
Two comments first off, holy rambling on about screws. :D

The second

One issue I have after reading the comments is that not everyone shares the same definition of machine screw as one of the posts for instance suggest any machine screw as long as you cut off the point. last I looked, machine screws don't have points. that is sheet metal screws.

Self drilling machine screws have points.
 

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
What debate are you looking for? Is it to say machine screws are compliant or that sheet metal screws are no problem if kept short.

FWIW I have used metal screws in the past but machine screws are not hard to find. I also keep green bonding screws in my truck since some panels are missing thm
 
What debate are you looking for? Is it to say machine screws are compliant or that sheet metal screws are no problem if kept short.

FWIW I have used metal screws in the past but machine screws are not hard to find. I also keep green bonding screws in my truck since some panels are missing thm

I don't see panels every day, but seen enough self-drilling sheet metal screws in place to recognize the inherent hazard associated with it. These would be a perfect application of plastic pop-rivets if I ever seen one.
 

kbsparky

Senior Member
Location
Delmarva, USA
Most of the Square D panel covers that I have installed lately have come with extra cover screws in the packets. I save `em in my assorted screws box, and have to use them from time to time when I encounter jobsites that are lacking.

I bet I have at least a dozen or so hanging around, so that is really not a problem for me.

Often times, on older panels, the screw holes are worn out, and the factory-supplied screws no long hold the cover in place. In those instances, using a larger screw such as a #12 sheet metal or machine screw in a panel designed for a #10 screw solves that dilemma. One more reason to keep a 6-in-1 tapping tool in your toolbox/truck.
 

iwire

Moderator
Staff member
Location
Massachusetts
Here is a factory Cutler Hammer 3R cover screw.

301Tek-1.jpg


3012Tek.jpg


Tek4.jpg


Given that I feel we are over thinking things.

Just use some screws and check for conductors in the way first.
 

iwire

Moderator
Staff member
Location
Massachusetts
Lets call those suicide screws......:sick:

Here is my thinking, it does not matter if it is a pointy screw or a blunt screw, if conductors are resting against the lip of the panel and you run a screw into them there is a darn good chance you will cause a short. I think the best advice is look before you screw. :angel:
 
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