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Discussion Starter · #1 ·
Hi Folks,
This is Bruce again from Plymouth, MI. Pretty sad...on a Saturday night doing this!

I can't say much about my project, but I would like your help with some questions about enclosing an outdoor power conditioning system in a NEMA 3R enclosure.

I don't know yet if I'll be able to purchase this enclosure then modify it or if I'll have to design one from scratch.

I know the enclosure has to mount to a cement pad with the enclosure's equipment mounting surface elevated above the pad a certain height. The air will get be very hot inside even ignoring internal electrical heat dissipation and sunlight so we will probably need an air conditioner (and a heater for low temps).

But my questions are:
a. Are conduit and junction boxes ever required INSIDE a utility enclosure?

b. Although we will put drain holes in the bottom of the enclosure, I read that the wire and conduits should pass low into the enclosure (well below the lowest hot terminal in the system) in the event of rain leaking through the conduit fittings. Does this mean that the junction boxes have to be watertight and low? Or can the junction boxes be placed on the side walls above the lowest hot terminal?

c. Does wiring from outside the enclosure generally come through conduit up and over the sides of the pad then into the enclosure? Is it ever done where the conduits goes vertically up through the pad and emerge inside through the enclosure bottom?

d. In the off chance we can pull off a design without an air conditioner, can a NEMA 3R enclosure have openings besides drain holes, conduit pass thrus, and door openings?

I would normally get copies of the NEMA and other standards but I only have tonight and tomorrow to complete this proposal and have neither the money nor the time to get them.


Premium Member
2,023 Posts
You could you not use a large traffic signal control cabinet. The pad mount do not have bottoms and you can put shelves or build a rack in them. They are designed for electronic equipment.
Just a idea.
McCain traffic, Bison Profab, Safetran.
Just did a Google search.

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