what is minimum distance from ground for outside PV combiner box.

[rollandelliott]

I have a mpv12 box. I am mounting it under a ground mounted solar array. the wires from the grid tie inverters to the box are a little short. therefore i'd like to mount this box only around 2' above the ground. is this acceptable under the NEC(national electric code)? It's pretty well protected from the elements since it under the panels.

[WizBandit]

rollandelliott,

The NEC is pretty much a guide that most AHJs (Inspectors) use and the final say-so is up to them. The NEC has has height limits for disconnects (breaker handles, grip handles) of a maximum of 6' 7" but really no lower limits. The AHJs will point out certain local codes if you are in a published "flood zone". The working space in front is a code issue, it needs to be 30" or the width of the equipment, nothing mounted under it can stick out more than either 5 or 6 inches, I don't have my NEC with me but I'd use 5" to be safe (bushes & weeds don't count). The working space in front should be 3 feet or more as well. I have a genset 60A breaker to my SW5548 mounted 12" off the ground and the inspector just said  not to use my foot to actuate it.

[rollandelliott]

inspector looked at it today and said height was fine but did not like the fact that it was mounted UNDER the solar panels forcing someone to walk 23 feet under the ground mount array to get to it. He said he would check the NEC and see what it says.

[Robin]

Your inspector is confusing the PV disconnect with the combiner. You do need a disconnect next to the controller and inverter stuff. UL states that if a Nema 3R box is mounted closer than 3 feet to the ground, it needs to be evaluated for rain bouncing up rather than just down. I would add a piece of foam window gasket material on the top of the cover to seal the gap between the chassis and the cover. That should do it.