Dry Location vs Damp or Wet Location

Status
Not open for further replies.
M

morepowerinc

Member
Hi, I am involved in a project in S. FL with roughly 300 light fixture to be installed under a brigde. The conduit and boxes are to be installed exposed on the underdect of the brigde. The location of the boxes is surrounded by 4' (four) foot tall concrete girders or beams that extend down 4' from the bottom of the bridge. It would be impossible for any type of rain or moisture to reach these boxes at any given time. The inspector on site is treating this location as a damp or wet location and I think it should be clasified as a dry location even if it is located outdoors.

Please advise.

morepowerinc
 
Re: Dry Location vs Damp or Wet Location

dry location would be indoors ,wet location would be where exposed to the weather and -condesation-
 
Re: Dry Location vs Damp or Wet Location

Per the definitions in Article 100 of the NEC, I would treat the location as at least a damp location.
 
Re: Dry Location vs Damp or Wet Location

From the 2002 NEC Definitions

Location, Damp. Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.

Location, Dry. A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction.

Location, Wet. Installations under ground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.

It is intended that the inside of a raceway in a wet location or a raceway installed under ground be considered a wet location. Therefore, any conductors contained therein would be required to be suitable for wet locations.
See 300.6(C) for some examples of wet locations and 410.4(A) for information on luminaires installed in wet locations.
See patient care area in 517.2 for a definition of wet locations in a patient care area.
 
Re: Dry Location vs Damp or Wet Location

If the inside of a raceway is a wet location, what's the point of liquidtight conduit?
 
Re: Dry Location vs Damp or Wet Location

Originally posted by paul32:
If the inside of a raceway is a wet location, what's the point of liquidtight conduit?
Click to expand...
To keep water from entering the enclosure. There is an exception to alow flexible metal conduit to be used in wet locations as long as it arranged so not to allow water to enter the enclosure and the wires have W in the designation such as THWN.
 
Re: Dry Location vs Damp or Wet Location

Wouldn't that mean water isn't in the conduit then either? If water can't get in the conduit then it should be a dry location. If water can get in the conduit, it can get in the enclosure.

I see NM used in LFNC outside to get to an air conditioning disconnect, and assumed the inside of liquidtight conduit was a dry location. I saw the handbook say wet location and was going to ask about it.
 
Re: Dry Location vs Damp or Wet Location

It would be impossible for any type of rain or moisture to reach these boxes at any given time
Click to expand...
How about Fog or evaporation after a rain shower trapped between the 4'beams

Craig
 
Re: Dry Location vs Damp or Wet Location

Originally posted by heco:
From the 2002 NEC Definitions


It is intended that the inside of a raceway in a wet location or a raceway installed under ground be considered a wet location. Therefore, any conductors contained therein would be required to be suitable for wet locations.
Click to expand...
This (above) is text from the Handbook. Although written by people involved in the Code making process it is not code. I can't find anything in the Code or the FPN's to support that the interior of a raceway in a wet location is a wet location.

I think the short run of NM in LTFNMC to an A/C nothing to worry about, but that's just me. :D
 
Re: Dry Location vs Damp or Wet Location

Originally posted by sandsnow:
I can't find anything in the Code or the FPN's to support that the interior of a raceway in a wet location is a wet location.
Click to expand...
I don't think there is a section that says that. :)

There is 300.5(D)(5) that requires wet location conductors for underground raceways or enclosures.

There is also 348.12(1) which tells us we can use FMC in wet locations if the wire is rated for it.

IMO that leaves the option of using LFMC in a wet location with dry location conductors. :)
 
Re: Dry Location vs Damp or Wet Location

Originally posted by ryan_618:
IF you really think raceways are impervious to water, see 225.22 and ask yourself...."why"?
Click to expand...
I don't think raceways in general are, but liquidtight should be.

What's the normal way to meet 225.22? Drill a hole in the bottom of the LB used to go from the meter socket into the house? I looked at my house and the PVC has no drain hole.
 
Re: Dry Location vs Damp or Wet Location

Conduit is not designed to be watertight. RMC couplings have no taper. PVC couplings have no taper. Plumbing fittings do. PVC conduit is glued together with no primer. The NEC is clear, that any conduit installed underground is a wet location. The conduit under the brige would get moisture in it from condensation. A conduit system heats up and cools off from the sun, this breating causes condensation.
 
Re: Dry Location vs Damp or Wet Location

A Nema 3R enclosure when installed in a wet location will protect the interior of that enclosure from any type of water from entering it such has dripping or driving rain. We can say that eventhough a Nema 3R enclosure can prevent water from entering the enclosure it will never prevent moisture or dampness from having a presence within that enclosure. If we can achieve the same protection from a roof, poured slab, bridge deck or even a permanent canopy why can't we install a Nema 1 enclosure in those location.
Most electrical installation which is installed in Parking Garages are installed with setscrew fittings and Nema 1 enclosures under the decks for lighting as well a power,would this be in violation of the NEC?
We all know that no matter what type or where we install exterior conduit it will always have condensation within the conduit.
 
Re: Dry Location vs Damp or Wet Location

I recommend to use "common sense" and experience to judge this, I live in a place very similar to Florida conditions, everything outdoors, seems to be in wet location, as a matter of fact, the condensation is perhaps worst than the rain, the enclosure NEMA 3R does not stop that, and some cases a heat resistance is needed, I am agree with the inspector.
 
Re: Dry Location vs Damp or Wet Location

If we say that condensation makes the inside of liquidtight conduit a wet location in a wet location, why can you call it a dry location in a dry location? I would think condensation can happen indoors.
 
Re: Dry Location vs Damp or Wet Location

Most indoor locations have controlled temperatures. When you reduce the magnitude and number of temperature changes, you reduce the condensation.
Don
 
Re: Dry Location vs Damp or Wet Location

I think the recent hurricanes pretty well say that ALL of Florida - even indoors - is a wet location :)

Certainly would apply outdoors. No doubt about that. Wouldn't matter where you put them.
daisy
 
Status
Not open for further replies.
Top