Nema 3r panel on roof

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Roscoe

Member
Location
Oh
Occupation
Electrician
This is my first Nema 3R panel mounted to unistrut, my question is ,before I pull my feeders, can I not it straight to unistrut with 3/8 bolts and spring nuts.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Are you asking about mounting it vertically to some type unistrut rack or mounting it laying on unisturt on the roof ?
 

Roscoe

Member
Location
Oh
Occupation
Electrician
mounting it vertically to the Unistrut using 3/8 bolts and spring nuts it is a standard issue 3 phase 200-amp Nema 3r panel enclosure I wasn't sure if I would need a backer board or if I'm good to mount it directly to Unistrut
 

kwired

Electron manager
Location
NE Nebraska
mounting it vertically to the Unistrut using 3/8 bolts and spring nuts it is a standard issue 3 phase 200-amp Nema 3r panel enclosure I wasn't sure if I would need a backer board or if I'm good to mount it directly to Unistrut
No wood, it will rot away. Nothing wrong with attaching to the strut. if you want some sort of backer use sheet metal somehow if you already are building the main frame out of strut.
 

Roscoe

Member
Location
Oh
Occupation
Electrician
Are you asking about mounting it vertically to some type unistrut rack or mounting it laying on unisturt on the roof ?
mounting it vertically to the Unistrut using 3/8 bolts and spring nuts it is a standard issue 3 phase 200-amp Nema 3r panel enclosure I wasn't sure if I would need a backer board or if I'm good to mount it directly to Unistrut
 

Roscoe

Member
Location
Oh
Occupation
Electrician
I have seen it that way.... why I was cautious,
okay was just curious it will be on a roof indirect sunlight but I do have almost 6 ft of substrate behind it made out of brick I simply tapcon Unistrut can masonry substrate and then attached to the strut that stupid hole on the back of Nema 3r panels always makes me leery it's simply a center mounting hole nipple, they put them on all Nema 3r panels and disconnects
 

kwired

Electron manager
Location
NE Nebraska
okay was just curious it will be on a roof indirect sunlight but I do have almost 6 ft of substrate behind it made out of brick I simply tapcon Unistrut can masonry substrate and then attached to the strut that stupid hole on the back of Nema 3r panels always makes me leery it's simply a center mounting hole nipple, they put them on all Nema 3r panels and disconnects
That "dimple" with the mounting hole in it is to keep space between the enclosure and the mounting surface, which reduces dirt buildup and moisture accumulation which will corrode the enclosure quicker if it is allowed to form there. Some extreme situations still get debris behind the enclosure and you have these problems anyway.

Some can possibly say you still need to have that space between the enclosure and the strut, but IMO in most cases no more contact than there is between strut and enclosure you are still ahead in possible future corrosion issues game.
 
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