Water ingress in Ex boxes?

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Shells

Member
Guys,

Just wanted to hear some thoughts on this - I have been hearing around our site that the guys have been sealing boxes (general purpose and Explosion proof included) with silicone because of water ingress. I know this is not a good practice. I am assuming they have minimum IP 65 rating. I am yet to confirm that the appropriate rated drains can be installed and if it would be effective based on the amount of water ingress. However just wondering if anyone has had challenges with water ingress into properly rated EX boxes and what are some recommendations. I'm thinking the most likely issue is an installation issue - improper seal through cable gland or compromised gasket or something of the sort. Any thoughts would be appreciated.
 

Smart $

Esteemed Member
Location
Ohio
You cannot stop water ingress in the form of moisture condensation. The proper method is to arrange equipment to drain even if that requires the use of drains. However, proper sealing of wet or damp location equipment is a listing requirement which takes precedence over installing drains into a faulty system. Field applied sealing methods which are not part of listing instructions IMO are a violation. Find and fix the fault. If water ingress is still excessive, you likely have equipment that is not properly rated for its location or it has degraded to such a level.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
In the NEMA world, just because it is an explosion proof enclosure does not mean that it is suitable for use in wet locations. An NEMA explosion proof enclosure that is also suitable for use in wet locations will have both the NEMA 4 (wet locations) and the NEMA 7 (explosion proof) markings.
 

Shells

Member
You cannot stop water ingress in the form of moisture condensation. The proper method is to arrange equipment to drain even if that requires the use of drains. However, proper sealing of wet or damp location equipment is a listing requirement which takes precedence over installing drains into a faulty system. Field applied sealing methods which are not part of listing instructions IMO are a violation. Find and fix the fault. If water ingress is still excessive, you likely have equipment that is not properly rated for its location or it has degraded to such a level.

Thanks for the reply. I think it is probably the latter based on the amount of water ingress. I agree we should be fixing the problem instead of placing the silicone.... my challenge now is getting the field guys to actually do it instead of taking the fastest way out!
 

Shells

Member
In the NEMA world, just because it is an explosion proof enclosure does not mean that it is suitable for use in wet locations. An NEMA explosion proof enclosure that is also suitable for use in wet locations will have both the NEMA 4 (wet locations) and the NEMA 7 (explosion proof) markings.

Point noted. I will need to verify both the NEMA rating and the IP rating for suitability in outdoor location
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Point noted. I will need to verify both the NEMA rating and the IP rating for suitability in outdoor location

You have several times mentioned "IP" rating. Is this installation in the EU or other non-US location?
 

Shells

Member
You have several times mentioned "IP" rating. Is this installation in the EU or other non-US location?

Oh yes thanks for pointing out. We follow US codes however we do have an installed base of European Equipment based on the equipment OEM. That's a whole other issue but unfortunately we have a mix on site so I will have to look at both NEMA and IP rating
 

Shells

Member
Right or wrong, at some one of the many classes, the hint was to run a small bit of silicone around the outside of the cap with your finger. NOT on the threads or faces themselves, but after the caps/cover are made up snug. Right or wrong, IDK

Hmm thats interesting - what about the use of belzona? Was that ever encouraged?
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Hmm thats interesting - what about the use of belzona? Was that ever encouraged?

I had to look that up. I'm not aware of any product line quite like Belzona here in the US. I suppose 3M may have comparable products but I've never run across them.

I would think that you would definitely want to use the polymer products, not the metal products. ptonsparky's suggestion was to apply a minimal seal that would still allow gas to vent from a fixture in the event something exciting happened in your raceway.
 

stgga

Member
Location
GA
You cannot stop water ingress in the form of moisture condensation. The proper method is to arrange equipment to drain even if that requires the use of drains. However, proper sealing of wet or damp location equipment is a listing requirement which takes precedence over installing drains into a faulty system. Field applied sealing methods which are not part of listing instructions IMO are a violation. Find and fix the fault. If water ingress is still excessive, you likely have equipment that is not properly rated for its location or it has degraded to such a level.


I agree. We use a UL50 rated a compression rubber base gasketing because the extruded foam stuff fails too often-so we're well sealed to start with. If a cooler is used and condensation is a possibility you can try a simple solution like desiccant bags but if that doesn't work you'll have to look at other options. We build a lot of purged enclosures so a drain is not an option so you have to take great care to prevent moisture and water in the first place.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I agree. We use a UL50 rated a compression rubber base gasketing because the extruded foam stuff fails too often-so we're well sealed to start with. If a cooler is used and condensation is a possibility you can try a simple solution like desiccant bags but if that doesn't work you'll have to look at other options. We build a lot of purged enclosures so a drain is not an option so you have to take great care to prevent moisture and water in the first place.
For an explosion proof enclosure?
 
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