Drains - hdbk109220040089

DOE-HDBK-1092-2004

4. At each entrance to an enclosure housing with an arcing or sparking device when used in

Class I Division 1 and 2 hazardous locations, seals must be as close as practicable to and in

no case more than 18 in. from such enclosures.

5. At each 2-inch or larger entrance to an enclosure or fitting housing terminals, splices, or taps

when used in Class I Division 1 hazardous locations, seals must be as close as practicable

to and in no case more than 18 inches from such enclosures.

6. Seals must be located in conduit systems when the conduit leaves the Class I Division 1 or

2 hazardous locations.

7. Seals must be located in cable systems when the cables either do not have a gastight or

vapor-tight continuous sheath or are capable of transmitting gases or vapors through the

cable core when these cables leave the Class I Division 1 or Division 2 hazardous locations.

NEC 502.5 requires the use of seals in Class II locations under certain conditions. Any

approved sealing fittings can be used to meet this requirement.

5.4.1.2 DRAINS

In humid atmospheres or in wet locations where it is likely that water can enter the interiors of

enclosures or raceways, the raceways should be inclined so that water will not collect in

enclosures or on seals but will be led to low points where it may pass out through drains.

Frequently the arrangement of raceway runs makes this method impractical if not impossible. In

such instances, drain sealing fittings shall be used. These fittings prevent accumulations of

water above the seal.

In locations usually considered dry, surprising amounts of water frequently collect in conduit

systems. No conduit system is airtight; therefore, it may breathe. Alternate increases and

decreases in temperature and barometric pressure because of weather changes or the nature

of the process carried on in the location where the conduit is installed will cause breathing.

Outside air is drawn into the conduit system when it breathes in. If this air carries sufficient

moisture, it will be condensed within the system when the temperature decreases and chills the

air. With internal conditions being unfavorable to evaporation, the resultant water accumulation

will remain and be added to by repetitions of the breathing cycle. In view of this likelihood, it is

good practice to ensure against such water accumulations and probable subsequent insulation

failures by installing drain sealing fittings with drain covers or inspection covers even though

conditions prevailing at the time of planning or installing may not indicate the need.

5.4.1.3 SELECTION OF SEALS AND DRAINS

Different types of seals and drains are made to be used for vertical or horizontal installations

and are to be used only for the purpose for which they were designed. Care shall be taken when

selecting and installing such fittings.

5.4.1.3.1

PRIMARY CONSIDERATIONS

The following primary considerations should be used when selecting seals and drains:

1. Select the proper sealing fitting for the hazardous vapor involved (i.e., Class I Groups A, B,

C, or D).

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