Rooftop Array GEC is back in 2014?

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c_picard

Senior Member
Location
USA
Does anyone have any background on how this happened? I have reviewed the ROP docs, and it looked like the CMP was bringing back 690.47(D), but had deleted the verbiage regarding rooftop arrays. Electrodes at ground mounts make sense, but the idea that a 8AWG piece of copper coming off a roof can help with a lightning strike has always seemed a little silly to me.

I'm just digging into the 2014, and the sentence that was struck-through in the ROP is in the text. I sure am hoping this is a typo. (already found a few others)

4-315 Log #3287 NEC-P04 Final Action: Accept in Part
(690.47(D) (New) )
________________________________________________________________
 
G

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Consulting Electrical Engineer - Photovoltaic Systems
c_picard said:
Does anyone have any background on how this happened? I have reviewed the ROP docs, and it looked like the CMP was bringing back 690.47(D), but had deleted the verbiage regarding rooftop arrays. Electrodes at ground mounts make sense, but the idea that a 8AWG piece of copper coming off a roof can help with a lightning strike has always seemed a little silly to me.

I'm just digging into the 2014, and the sentence that was struck-through in the ROP is in the text. I sure am hoping this is a typo. (already found a few others)

4-315 Log #3287 NEC-P04 Final Action: Accept in Part
(690.47(D) (New) )
________________________________________________________________
Click to expand...
<deleted> I saw GEC and read it as EGC. Never mind. Move along. Nothing to see here...
 
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SolarPro

Senior Member
Location
Austin, TX
(D) Additional Auxiliary Electrodes for Array Grounding.
A grounding electrode shall be installed in accordance
with 250.52 and 250.54 at the location of all ground- and
pole-mounted PV arrays and as close as practicable to the
location of roof-mounted PV arrays. The electrodes shall be
connected directly to the array frame(s) or structure. The dc
grounding electrode conductor shall be sized according to
250.166. Additional electrodes are not permitted to be used
as a substitute for equipment bonding or equipment grounding
conductor requirements. The structure of a ground- or
pole-mounted PV array shall be permitted to be considered
a grounding electrode if it meets the requirements of
250.52. Roof-mounted PV arrays shall be permitted to use
the metal frame of a building or structure if the requirements
of 250.52(A)(2) are met.

Exception No. 1: An array grounding electrode(s) shall
not be required where the load served by the array is integral
with the array.

Exception No. 2: An additional array grounding electrode(
s) shall not be required if located within 1.8 m (6 ft)
of the premises wiring electrode.
 
Z

Zee

Senior Member
Location
CA
Whoa. More work.

Thanks SolarPro.

What is a TIA?

Will this DC electrode need to be bonded to the existing premises electrode with a bonding jumper?
 
G

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Since this is an auxiliary electrode (the section calls it that!), it does not have to be bonded.
A TIA is a temporary interim amendment or close to those words. It is used for urgent safety related changes which cannot wait for the next cycle.
However jurisdictions that have adopted the code have to adopt the TIA to make official.
That in turn does not stop inspectors from honoring it informally.

Sent from my XT1080 using Tapatalk
 
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