Rooftop solar junction boxes (Florida)

tom08588

Member
Location
Florida
Occupation
Engineer
On shingle roofs we use the popular SolaDeck junction boxes. However, on tile, flat, and metal roofs we generally have been using Kraloy JBX666 or JBX664 boxes where needed on roofs. An inspector for Hillsborough county, FL mentioned that junction boxes and enclosures need to be "solar rated" in order to pass inspection. I asked him what made a box "solar rated" like a certain UV/UL/NEMA rating, but I think believe he just wants us to use junction boxes that are designed and meant for use on solar PV projects. Our installers prefer the dimensions of a 6x6x6/4 box, so I'm trying to find a brand that is comparable in size while still explicitly stated they are meant for solar PV arrays. Does anyone have recommendations for a box?
 

jaggedben

Senior Member
His requirement is BS. You can use anything that's appropriately rated for the voltage and conditions, such as outdoor wire nuts. 690 says that any wiring methods approved elsewhere in the code may be used for PV. However, if you're not feeling like you can win that battle, there's this jbox that is supposedly listed to UL 1471.


I'm not endorsing the particular seller here, that's just the first result that came up.

UL 1741 is a standard for inverters, not junction boxes, so I think this listing is basically a sham and just means that they paid an NRTL. You might tell the inspector that, but it's what he's asking for, and I'm not aware of anything similar in the same scale.
 

Zee

Senior Member
Location
CA
Do you mean a box to transition rooftop wiring to THWN .....and also penetrate the roof with your wiring?
There is no box like that for metal, flat or tile roofs.
You use a box to transition wiring then run conduit to penetration, and penetrate through a properly sealed flashing (appropriate for roof type) with conduit.

Otherwise if you are talking about a standard J-box (transitioning to conduit) then:

Two-gang Bell box.

Get "Deep" version for extra wiring space.

Stainless steel TEK Screw it to rail.
Drill two weep holes. (good idea for any outdoor box!)

I prefer to mount J-box under the panels for aesthetics.

Solid aluminum box and metal cover. Will last.

Get the 5@3/4" hole variety. Use 3/4 x 1/2" threaded reducing bushings when 1/2" fittings used.
(You can reduce an outlet hole, but not vice versa.)

Nice feature of a threaded metal outlet box is no grounding bushings needed - which are often difficult.
 
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