At a propane dispensing location, the motor switch stopped working today because the device box was filled with water. It is a hazardous location device box, 32" from the scale where they fill the tanks. The mating surfaces of the box are beginning to rust and corrode. I would think that a box rated for Class 1 Div 1 would by default also be weatherproof. Maybe I'm wrong (again). Can a class 1 div 1 box be assumed to be weatherproof? Or should I look for a box also marked 3R? I don't know that I've ever seen a hazardous location box also marked 3R. If no such thing exists, how can I alleviate this problem?
Haz. Location Boxes rated for outdoors?
- Thread starter JES2727
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
A lot of them are 3R. But unless it is labeled as 3R its not.
If it is rusting it is probably not 3R.
If it is rusting it is probably not 3R.
Last edited:
ohm
Senior Member
- Location
- Birmingham, AL
An explosion proof box must have a certain width of un-gasketed metal along the perimeter of the lid to sub-cool any gasses which may have exploded inside the box from escaping.
Some manufacturers insert a groove outside of this flat area to insert an "O" ring to obtain a dual rating, which would be 3R and explosion proof.
On simple explosion proof enclosures used outside I would silicone the top & side cracks, of the lid, to prevent di-urnal breathing from sucking in rainwater at night when the box cooled down.
If you calk the flat surfaces you void the explosion proof rating.
Some manufacturers insert a groove outside of this flat area to insert an "O" ring to obtain a dual rating, which would be 3R and explosion proof.
On simple explosion proof enclosures used outside I would silicone the top & side cracks, of the lid, to prevent di-urnal breathing from sucking in rainwater at night when the box cooled down.
If you calk the flat surfaces you void the explosion proof rating.
- Location
- Illinois
- Occupation
- retired electrician
Ohm,
You need to use an enclosure listed for the purpose. You can take a NEMA 7 or 9 and make it a 3R or 4 by adding exterior caulk.
edit: I need to read my posts before posting them. It should say "can't take a NEMA ..."
You need to use an enclosure listed for the purpose. You can take a NEMA 7 or 9 and make it a 3R or 4 by adding exterior caulk.
edit: I need to read my posts before posting them. It should say "can't take a NEMA ..."
Last edited:
ohm
Senior Member
- Location
- Birmingham, AL
Don, I agree we should use enclosures listed for the application. When I mentioned that I installed calk on the lid of enclosures it was a short term fix. I should mentioned that I inherited several thousand 4x enclosures in my plant that were installed outside and it was brought to my attention that moisture was becomming a maintenance nightmare. I had the boxes calked but future installations were specified 4x / 3R.
This was only a good short term fix. Sorry if I misled anyone.
This was only a good short term fix. Sorry if I misled anyone.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
ohm said:
Moisture is frequently a problem in outdoor installations. Just normal air pressure changes will bring moisture laden air into the boxes and when they cool, water condenses inside the boxes.
About the only practical things you can do are to install drains and/or heaters.
Ragin Cajun
Senior Member
- Location
- Upstate S.C.
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