# Can I mount din rail in a nema 3r weatherproof enclosure?



## Peewee0413 (Oct 18, 2012)

Family guy said:


> First question is can I do this with no backplate, And second is what is the best method. Drill and tap? Self tap? Or bolt and nut?
> 
> 
> Sent from my iPhone using Tapatalk


Why opt to not use a backplate?

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## Family guy (May 15, 2016)

I don’t have one at this point.


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## oliquir (Jan 13, 2011)

yes but it may lose its 3r rating unless you can spotweld the din rail


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## Family guy (May 15, 2016)

That is the question. If it loses the 3R rating if I drill through the back of the box. Going to have to do some checking.


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## joebanana (Dec 21, 2010)

Family guy said:


> That is the question. If it loses the 3R rating if I drill through the back of the box. Going to have to do some checking.
> 
> 
> Sent from my iPhone using Tapatalk


If you use neoprene washers on the outside you should be good.


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## Family guy (May 15, 2016)

Do you know where I could get some neoprene washers?


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## Peewee0413 (Oct 18, 2012)

Family guy said:


> Do you know where I could get some neoprene washers?
> 
> 
> Sent from my iPhone using Tapatalk


Hardware store.. plumbing section, sometimes in bolt bin area. Neoprene is used for sinks, washers, toilets etc.

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## Family guy (May 15, 2016)

Thanks 


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## joe-nwt (Mar 28, 2019)

joebanana said:


> If you use neoprene washers on the outside you should be good.


This. Many outdoor panels come with washers to seal the mounting holes at installation.


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## B-Nabs (Jun 4, 2014)

joebanana said:


> If you use neoprene washers on the outside you should be good.





joe-nwt said:


> This. Many outdoor panels come with washers to seal the mounting holes at installation.


2/2 joes agree 

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## Wavelet8 (Jan 11, 2014)

I would just drill and tap. If your concerned about water you can place some sealing substance on the 8-32 threads.


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## splatz (May 23, 2015)

Family guy said:


> Do you know where I could get some neoprene washers?
> 
> 
> Sent from my iPhone using Tapatalk



You can buy them but I usually have sheet metal tek screws around that come with the gasket washers, I just use those. 










It's also fine to just use some flat gasket material on the outside between the washer and the box. 



I usually back it up by coating the gasket or washer with a little silicone, can't hurt, probably helps. 



I have done it this way for years. Remember a 3R as far as I know will always be set up to drain if a little water gets in, so at worst you'll have some seepage from the bolt hole down to the floor of the container where it will escape, harmless. If you can help it don't put anything below holes. 



Another thing to consider, if the enclosure was made for a back plate, you can usually mount din rail or strut vertically between the holes made for the back plate, then mount the horizontal din rail to the vertical. I actually sometimes much prefer this method if you're mounting anything big in there.


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## MHElectric (Oct 14, 2011)

Wavelet8 said:


> I would just drill and tap. If your concerned about water you can place some sealing substance on the 8-32 threads.


Agreed. Why would drilling into the back of a NEMA 3R box take away it's rating? You know there's holes on the back side for mounting to a wall, so why would zipping a dinner rail with a couple of screws make it any less outdoor rated?


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## dronai (Apr 11, 2011)

Drill and tap 8-32


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## paulengr (Oct 8, 2017)

If the metal isn’t thick enough taps fail so then bolt and nut. I use self tapping screws mostly but be careful of what’s behind the panel.


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## Cow (Jan 16, 2008)

3R boxes have open factory holes at the back for securing the box.


I'm not sure why sealing washers would be necessary for field installed holes when they are not provided or installed for the factory drilled holes?


I use #10 panhead self drillers right through the back. No silicone, no sealing washers, etc.


A 3R box is simply a rainproof box. It is not intended to keep all water out, but simply to keep it off components inside and drain what may get in to the drain holes in the corners of the box if needed.


If this was a 4X box or similar NEMA rating, I would agree with sealing the holes you make to maintain the NEMA rating.


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## Family guy (May 15, 2016)

Thanks for all your input. Sometimes I feel like I just overthink things too much, but If I know to do something I need to do it. Sometimes I don’t know and am trying to learn and work through issues and there is a lot more weight doing this by yourself and not just doing what your told. 
Just to let you know at the end of the day I got the wrong washers, and got spun around a bit, then I actually reverted back to asking a local electrician that knows the AHJ of the area I was doing the project in and decided to self tap and silicone because there was another metal plate behind the enclosure. Then bought some silicone to touch it up. 



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## JRaef (Mar 23, 2009)

Type 3R does not actually mean that water will not enter an enclosure, only that it will not get to any live parts. The bigger concern to me is actually the corrosion aspect. Drilling through the back will expose the edges of the holes to moisture and eventual rusting. Using sealing washers against the screws will help prevent that.


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