fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
Section/Paragraph: 110.28 Added Text
Added Text
110.28 Enclosure Types.
....
Table 110.28 shall be used for selecting these enclosures for use in specific locations other than hazardous (classified) locations. The enclosures are not intended to protect against conditions such as condensation, icing, corrosion, or contamination that may occur within the enclosure or enter via the conduit or unsealed openings.
[version 1]If a 3R enclosure is in a wet location, the entire interior of the enclosure shall be considered a damp location and any interior space below the top of knockouts or field-made holes for conductors shall be considered a wet location.
[version 2]If a 3R enclosure is in a wet location, the entire interior of the enclosure shall be considered a damp location.
[version 3]If a 3R enclosure is in a wet location, the entire interior of the enclosure shall be considered a bone dry location.
Substantiation:
There are periodic discussions about whether or not the interior of a 3R enclosure (in a wet location) is to be considered damp or wet. This almost always stems from the question of the suitability of NM cable connections to 3R. It is appropriate for the NEC to resolve this question. The new text perhaps should also refer to one or more of "3", "3S", "3X', "3RX", and "3SX".
Substantiation for [version 1]:
3R enclosures are not designed to exclude water under the UL50 testing regime. They are designed to prevent water from contacting the device(s), if any, installed in them and to prevent water from rising in the enclosure high enough to cover connections to devices. The high-water mark is, as I understand it, a line below any devices or connections to devices installed in the enclosure and a line above to top of any penetration of the enclosure for conductors.
Thus I believe any cable or conductor entering the enclosure (other than ones entering through a "3R-rated" hub fitting) to be exposed to water. In addition, because metallic enclosures mounted in wet locations must be spaced a minimum of 6 mm. (? in.) between the exterior back of the enclosure and the surface it is mounted on, that cable sheaths are exposed to the wet location when coming from a surface which is the boundary for a dry location. Even if the cable is enclosed in a raceway, the interior of the raceway is considered wet in this instance.
I further believe that any conductor or cable exposed to water must be rated for wet locations.
Substantiation for [version 2]
3R enclosures are not designed to exclude water under the UL50 testing regime. They are designed to prevent water from contacting the device(s), if any, installed in them and to prevent water from rising in the enclosure high enough to cover connections to devices. In this case the high-water mark is, as I understand it, a line below any devices or connections to devices installed in the enclosure and a line below the bottom of any penetration of the enclosure for conductors. Thus any conductor would not be exposed directly to water unless it contacted the interior wall or base of the enclosure. I understand that water is allowed to "sheet" down the interior walls under the UL50 testing regime. Thus the location is not a wet location, but an enclosure containing water is surely a damp location.
Substantiation for [version 3]
3R enclosures are not designed to exclude water under the UL50 testing regime. They are designed to prevent water from contacting the device(s), if any, installed in them and to prevent water from rising in the enclosure high enough to cover connections to devices. From numerous anecdotal instances from the field, there has "never" been a problem using conductors not rated for wet or damp locations. Thus the interior of a 3R enclosure should be considered bone dry.
Added Deleted
Added Text
110.28 Enclosure Types.
....
Table 110.28 shall be used for selecting these enclosures for use in specific locations other than hazardous (classified) locations. The enclosures are not intended to protect against conditions such as condensation, icing, corrosion, or contamination that may occur within the enclosure or enter via the conduit or unsealed openings.
[version 1]If a 3R enclosure is in a wet location, the entire interior of the enclosure shall be considered a damp location and any interior space below the top of knockouts or field-made holes for conductors shall be considered a wet location.
[version 2]If a 3R enclosure is in a wet location, the entire interior of the enclosure shall be considered a damp location.
[version 3]If a 3R enclosure is in a wet location, the entire interior of the enclosure shall be considered a bone dry location.
Substantiation:
There are periodic discussions about whether or not the interior of a 3R enclosure (in a wet location) is to be considered damp or wet. This almost always stems from the question of the suitability of NM cable connections to 3R. It is appropriate for the NEC to resolve this question. The new text perhaps should also refer to one or more of "3", "3S", "3X', "3RX", and "3SX".
Substantiation for [version 1]:
3R enclosures are not designed to exclude water under the UL50 testing regime. They are designed to prevent water from contacting the device(s), if any, installed in them and to prevent water from rising in the enclosure high enough to cover connections to devices. The high-water mark is, as I understand it, a line below any devices or connections to devices installed in the enclosure and a line above to top of any penetration of the enclosure for conductors.
Thus I believe any cable or conductor entering the enclosure (other than ones entering through a "3R-rated" hub fitting) to be exposed to water. In addition, because metallic enclosures mounted in wet locations must be spaced a minimum of 6 mm. (? in.) between the exterior back of the enclosure and the surface it is mounted on, that cable sheaths are exposed to the wet location when coming from a surface which is the boundary for a dry location. Even if the cable is enclosed in a raceway, the interior of the raceway is considered wet in this instance.
I further believe that any conductor or cable exposed to water must be rated for wet locations.
Substantiation for [version 2]
3R enclosures are not designed to exclude water under the UL50 testing regime. They are designed to prevent water from contacting the device(s), if any, installed in them and to prevent water from rising in the enclosure high enough to cover connections to devices. In this case the high-water mark is, as I understand it, a line below any devices or connections to devices installed in the enclosure and a line below the bottom of any penetration of the enclosure for conductors. Thus any conductor would not be exposed directly to water unless it contacted the interior wall or base of the enclosure. I understand that water is allowed to "sheet" down the interior walls under the UL50 testing regime. Thus the location is not a wet location, but an enclosure containing water is surely a damp location.
Substantiation for [version 3]
3R enclosures are not designed to exclude water under the UL50 testing regime. They are designed to prevent water from contacting the device(s), if any, installed in them and to prevent water from rising in the enclosure high enough to cover connections to devices. From numerous anecdotal instances from the field, there has "never" been a problem using conductors not rated for wet or damp locations. Thus the interior of a 3R enclosure should be considered bone dry.
Added Deleted
