Conduit Supports in a Wet Location

esox39

Member
I was always told while running conduit outdoors, on a wall, a 1/2" space was needed behind the conduit. That's why backstraps or minis were used. I can't find this in the NEC. Is this requirement of the NEC or a trade practice?
 

Dennis Alwon

Moderator
Staff member
I thought it used to be, ... 70's? 80's? But it was worded that you only needed it on horizontal runs, not vertical. That's the way I remember it.
I don't ever recall it being in the nec but early 70-80's I wouldn't know. I see it done with strut but usually only when there are multiple runs.
 

dkidd

Senior Member
There is this for indoor
300.6
(D) IndoorWet Locations. In portions of dairy processing
facilities, laundries, canneries, and other indoor wet locations,
and in locations where walls are frequently washed or
where there are surfaces of absorbent materials, such as
damp paper or wood, the entire wiring system, where installed
exposed, including all boxes, fittings, raceways, and
cable used therewith, shall be mounted so that there is at
least a 6-mm (1⁄4-in.) airspace between it and the wall or
supporting surface.
 

Dennis Alwon

Moderator
Staff member
There is this for indoor
300.6
(D) IndoorWet Locations. In portions of dairy processing
facilities, laundries, canneries, and other indoor wet locations,
and in locations where walls are frequently washed or
where there are surfaces of absorbent materials, such as
damp paper or wood, the entire wiring system, where installed
exposed, including all boxes, fittings, raceways, and
cable used therewith, shall be mounted so that there is at
least a 6-mm (1⁄4-in.) airspace between it and the wall or
supporting surface.
Good find-- that must be what he remembers-- I did not know about this section . :thumbsup:
 

infinity

Moderator
Staff member
The 1 ∕ 4" airspace is also required for enclosures covered under Article 312 in damp and wet locations but not the raceways.
 

jap

Senior Member
I remember it also although I never use 1 hole straps anyway for running outdoor conduit with compression couplings. The standoff of the coupling and using 1 hole straps just makes the run look bad.

That's also why the mounting nubs on most all 3r enclosures protrude out about 1/4".

JAP>
 
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