Behind the fence

[ggunn]

Is there a code article specifying the height of a fence surrounding a ground mounted array? I know we usually say 7', but is it in the NEC, and if so, where?

 

[SolarPro]

See 110.31

What's the application? Is this in someone's backyard or back 40? Or is this a 1,000-volt utility-scale application?

If the former, I've always understood this to be up to the AHJ. What makes the exposed wiring no longer readily accessible, per 690.31(A)? Some people add skirting around the subarray tables. Some people put some sort of wire guard (see photo #4 in link below) on the back of the ground mount. Some people fence the field, but not necessarily using a 7' fence. A 4' fence with a lock on the gate might meet this requirement, depending on the site, the use patterns and other design measures (like the use of wire screens). I'd develop a proposal that seems reasonable and run it by the AHJ.

If the latter, then yes, you're looking at a 7' fence at the very least.

http://www.homepower.com/articles/solar-electricity/equipment-products/array-wire-management

 

[SolarPro]

(The 7' fence requirement is found in 110.31.)

Sorry for the duplicate info, I didn't think the changes to my previous post had been accepted. Not sure why the photo attachment didn't take...

 

[ggunn]

See 110.31

What's the application? Is this in someone's backyard or back 40? Or is this a 1,000-volt utility-scale application?

It's somewhere in the middle. It's several ground mount systems of various sizes from 20kW to 200kW on school campuses. They are bipolar arrays with maximum DC voltages of around +/- 550V.

Thanks for the references; I will check them out.

 

[SolarPro]

I know Austin Energy would require a 7' fence, as I did some school projects for them in the past. I also did some similar projects for the TX State Energy Conservation Office that did not require a fence. These were all pole mounts, so any exposed wiring was technically not readily accessible by virtue of the height of the arrays.

A ground-mount is inherently more difficult to secure. Even if you can block access to the single conductor wiring, how do prevent kids from climbing on the arrays? A 7' fence might be the only way to really secure things.

(By the time you factor in the fencing costs, carports or shade structures might be more cost effective - and useful.)