NEMA 4X panels allowed rain water to enter

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Isaiah

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Electrical Inspector
Correct me if I’m wrong, but I thought a Nema 4X SS enclosure would NOT allow water ingress if left lying flat (facing up) outdoors in the rain. However....We have two large control panels that were stored overnight (in the rain) and now show approximately 1.5” of water inside the panels - one has already a begun to rust. Power supplies, PLC with I/O modules, relays etc will probably have to be replaced.
Are these panels simply poorly constructed? Both have UL labels.


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They should be watertight when installed correctly. I don't think they are designed to be laid on their back with the door facing up. The enclosure is intended to shed water, however entry may occur if water is allowed to puddle around gaskets.
 
I don't think that much rain water accumulating in the panel can be explained by passive infiltration of water pooling around a gasket. I would expect that much water if the panel door were left wide open. Were any fittings/equipment installed through the surface and if so were those fittings NEMA 4 rated? Is the gasket intact and seated properly? Were the latches engaged?
 
The NEMA 4 (same for 4X) test involves a pressurized stream directed at the box from many angles. It almost like a firehose. If it passes, I wouldn’t expect any water ingress in a normal application, regardless of orientation.

It’s possible that field installed devices or penetrations were not installed in a manner conducive to maintaining the rating.
 
EC Dan said:
I don't think that much rain water accumulating in the panel can be explained by passive infiltration of water pooling around a gasket. I would expect that much water if the panel door were left wide open. Were any fittings/equipment installed through the surface and if so were those fittings NEMA 4 rated? Is the gasket intact and seated properly? Were the latches engaged?
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Good observation. I think the Estop was loose in the front panel allowing some amount of water to enter but I think the gasketing was also less than perfect


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Isaiah said:
Correct me if I’m wrong, but I thought a Nema 4X SS enclosure would NOT allow water ingress if left lying flat (facing up) outdoors in the rain. However....We have two large control panels that were stored overnight (in the rain) and now show approximately 1.5” of water inside the panels - one has already a begun to rust. Power supplies, PLC with I/O modules, relays etc will probably have to be replaced.
Are these panels simply poorly constructed? Both have UL labels.


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Click to expand...
Photos.
 
retirede said:
The NEMA 4 (same for 4X) test involves a pressurized stream directed at the box from many angles. It almost like a firehose. If it passes, I wouldn’t expect any water ingress in a normal application, regardless of orientation.

It’s possible that field installed devices or penetrations were not installed in a manner conducive to maintaining the rating.
Click to expand...

I tend to agree - the panel has a UL label so maybe someone failed to latch the doors tightly shut?


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Even if the latches were not set if the door was mostly closed how would water get inside there's a lip that goes all the way around unless it was sitting in a pool of water I don't see how water could get inside in that kind of quantity just from the door. I'm guessing there's a hole somewhere that's not sealed properly. Maybe somebody installed a push button or a light without installing the gasket behind it and water pooled up around it.
 
petersonra said:
Even if the latches were not set if the door was mostly closed how would water get inside there's a lip that goes all the way around unless it was sitting in a pool of water I don't see how water could get inside in that kind of quantity just from the door. I'm guessing there's a hole somewhere that's not sealed properly. Maybe somebody installed a push button or a light without installing the gasket behind it and water pooled up around it.
Click to expand...

I definitely think this is the case - still researching


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Isaiah said:
I tend to agree - the panel has a UL label so maybe someone failed to latch the doors tightly shut?


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That was my first thought, I haven't seen many enclosures (installed or ready to install) that had all latches properly done up.
 
Type 4 requires it withstand 65GPM of water from a 1” nozzle aimed from ANY direction, including being aimed from the back right at the door lip. That’s why Type 4 enclosures have more clamps or latch points than Type 12.

Were they new empty boxes still in the factory shipping materials? New boxes are shipped with the doors purposely NOT sealed tight (sometimes wedged open with inserts). Otherwise they would bow out going over mountains or in a plane, or suck in going to lower elevations. So if these were brand new unused enclosures, they were not sealed and should have been protected from rain.

If they were already used and built into being an assembly, then either someone failed to properly clamp the doors shut, or someone mounted a non-type 4 device somewhere on the outside.
 
NEMA 4X boxes -if correct installed-are sealed enough. However, since the junction box it is at a lower position than the conduits, cable tray and other parts of electrical installation, accumulation of water it is possible from conduits, glands and through cables-along the conductor or under the jacket. NEC Art.314.15 recommends to provide drainage openings in order to purge the water.
 
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