Weatherproof Surface Mounted Box

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electb

Member
If you do not use the mounting brackets that are furnished with a weatherproof box to mount it, does it still have the weatherproof rating?
One of my co workers says that he has seen on one of the manufacturers website that drilling two holes in the back of the box is acceptacle as long as you seal the holes with silicone after installation.
We cannot find this on any manufacturer's website. Does anyone know if this is accurate and if so, where do you find the documentation?

Thank you for your time.
 

iwire

Moderator
Staff member
Location
Massachusetts
This is one of those times I care more about it staying firmly mounted and not much about the listing.

I silcone the back before I mount it and make a drain on the bottom so the box ends up more like a NEMA 3R than watertight box
 

electricman2

Senior Member
Location
North Carolina
Occupation
Retired Electrical Contractor
I drill through the back and use sealant. We all know the flimsy brackets furnished with the box will not last any length of time.
 

JGRC

Member
Location
Texas
I've never mounted one with the provided feet or seen one mounted with the feet. Drilling the back was the way to go for long term duration. Never looked up what the manufacture says about it though. For me it was one of those things you learn as an apprentice and see everyone does the same way and never questioned it.....until now

I did however just install some PVC Carlton boxes for a saltwater aquarium and the feet are already integrated in the box so i did use those. Interesting enough those knockouts for drilling/mounting through the back were there.
 

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DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
I've lost count of the number of times I've pulled apart an outside "weatherproof" outlet and found a puddle of water at the bottom of the box. Article 110 does say we should follow manufacturer instructions. I believe the box was engineered the way it was for a reason. I think, mostly, though is that most of the time the water infiltration stems from a bad conduit connector. The connector should be liquid or rain-tight (with a gasket) and sometimes its hard to screw the connector in all the way even with a wrench!
 

electb

Member
update from original poster.

update from original poster.

As the AHJ for inspections here, we needed to find out and be able to have documentation.

We were able to talk with an engineer yesterday with Raco. To drill any holes in this box for any purpose is against manufacturer's instructions and voids the UL listing. Additionally, he informed us that all threaded holes should be sealed with some sort of listed sealant to achieve waterproof listing.

I am just adding this for your own information if needed in the future.
 

iwire

Moderator
Staff member
Location
Massachusetts
I've lost count of the number of times I've pulled apart an outside "weatherproof" outlet and found a puddle of water at the bottom of the box.

I always make a drain, either cut the gasket on the bottom edge or drill a small hole in the box.

Water always gets in, it needs a place to get out.
 

kwired

Electron manager
Location
NE Nebraska
I use the big hole in the back and a fender washer.
How do you enter with a raceway or cable in the back if you mounted it there?:D

I've lost count of the number of times I've pulled apart an outside "weatherproof" outlet and found a puddle of water at the bottom of the box. Article 110 does say we should follow manufacturer instructions. I believe the box was engineered the way it was for a reason. I think, mostly, though is that most of the time the water infiltration stems from a bad conduit connector. The connector should be liquid or rain-tight (with a gasket) and sometimes its hard to screw the connector in all the way even with a wrench!

Outside the far southwest, you will have more water enter because of condensation in raceways then will ever leak through fittings - possibly even if you used set screw fittings in some instances. Condensation occurs in environment where there is moderate or above humidity and happens almost daily when it cools off overnight. You could still have this problem in the far southwest at times but is not as big of a problem as most the rest of the country.

I always drill drain holes in bottom of these boxes, if you don't they fill up with water and destroys the device installed, or at very least rusts the bottom mounting screw or even bottom cover mounting screws and you can't get them out. Often need to replace the entire box when that happens, as you break something trying to get it opened/device removed.
 

DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
I always make a drain, either cut the gasket on the bottom edge or drill a small hole in the box.

Water always gets in, it needs a place to get out.

So you're basically constructing a NEMA 3R enclosure..
 

kwired

Electron manager
Location
NE Nebraska
Exactly.

The NEC requires raceways installed outside to drain so what better way to do it.
If it has no place to drain and freezes in winter time - it will drain after that - seen that many times. Usually more so in a low spot in a raceway then a bell box bursting open.
 
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