DIN Rail Mounting Screw Size

Does no one use metric screws?


If you intend to follow NFPA 79, then here are a few highlights to consider:

11.2.1.5 Threaded fasteners with machine threads shall be used to attach components to a subplate

11.2.5.1 Steel subplate thickness shall provide engagement of at least 2 full threads

11.2.1.5.4 Sheet metal screw, rivets, welds, solders, or bonding materials shall not be used to mount component to subplate

Exception: Rivets shall be permitted to be used for attaching mounting rails and wiring channels provided the exposed surface is smooth and free from any portion of a protruding stud.


The self drilling screws which are often used by electricians are typically sheet metal screws, therefore would not be NFPA79 compliant.

Pop rivets are more than adequate for DIN rail and wire duct, but I certainly wouldn't use them for mounting other components.
 
Din rail and wire duct are not considered components in the context of a panel.
you only need to use a taped screw if you are using it a grounding(Bonding) means for the din rail. if you do that then it is not considered as part of the mounting but as a separate grounding device it must not be used to mount the rail and must be Radley identified as the grounding point ( Green colored screw) and the paint must be scraped off at the point of contact and aluminum din rail may never be used as a grounding buss. I have seen some panel shops use double sided tape to mount the wire duct, in fact at one time you could by the duct with the tape already mounted.
 
So you have one operation to drill the panel, stop and put down the drill, pick up the next one with the tap in it, dip the end in cutting oil, drive it in, then drive it out, then put that machine down, then clean away excess oil and the little bits of metal that come out of the tap, then pick up a device to fit and tighten the screw being careful not to cross thread, perhaps adding a shakeproof washer. How much time could you save if you missed out the tapping bit but still ended up with M4, M5 and M6 tapped holes. I really should buy shares in one of these Taptite companies.

Everything in the enclosure is marked first, drilled, tapped then cleaned out. But we only build very small panels ourselves generally to a standard template. I can see the time saving using self tapping screws, sure.

And don't worry, you haven't offended your long lost mates here in NZ... although when Brexit turns to custard please don't all move here... we do speak English, but sometimes I think half you lot don't anymore!
 
I always drill & tap, almost always using a drill to tap.

I used to work for a machine builder that always used 'Tek's' self drilling screws for EVERYTHING. The drill ends frequently dulled before the hole was through, or broke, and when trying to take the screws out it was a PITA. I never spec or use self drilling screws for my projects.
 
We had a UL508A panel shop. Drilled and tapped, used Tap Magic, for 10-32 x 1/2". The Greenlee combo sets work well IF you use a clutching battery drill with generous TM. If you use regular (good quality) taps, they last forever, but the Greenlee eliminates the need for separate operations. Did them both, depending how the spirit moved us.

I still have a set of the Greenlee's at home; be amazed at when they come in handy.
 

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