grounding question and confusion

[shortcircuit2]

HERE IS THE 2005 GEC RULES:

690.47 Grounding Electrode System
(A) Alternating-Current Systems If installing an ac system, a grounding electrode
system shall be provided in accordance with 250.50 through 250.60. The grounding
electrode conductor shall be installed in accordance with 250.64.
(B) Direct-Current Systems If installing a dc system, a grounding electrode system shall
be provided in accordance with 250.166 for grounded systems or 250.169 for ungrounded
systems. The grounding electrode conductor shall be installed in accordance with 250.64.
(C) Systems with Alternating-Current and Direct-Current Grounding
Requirements Photovoltaic power systems with both alternating-current and directcurrent
(dc) grounding requirements shall be permitted to be grounded as described in (1)
or (2):

(1) A grounding-electrode conductor shall be connected between the identified dc
grounding point to a separate dc grounding electrode. The dc grounding-electrode
conductor shall be sized according to 250.166. The dc grounding electrode shall
be bonded to the ac grounding electrode to make a grounding electrode system
according to 250.52 and 250.53. The bonding conductor shall be no smaller than
the largest grounding electrode conductor, either ac or dc.
(2) The dc grounding electrode conductor and ac grounding electrode conductor shall
be connected to a single grounding electrode. The separate grounding electrode
conductors shall be sized as required by 250.66 (ac) and 250.166 (dc).


I see no mention of a GEC being needed at an Array for the modules or racking…2005 NEC


Handbook comments 2005 NEC:

Inverters used in PV power systems usually contain a transformer that isolates the dc
grounded circuit conductor from the ac grounded circuit conductor. This isolation
necessitates that both a dc and an ac grounding system be installed. The two grounding
systems are to be bonded together or have a common grounding electrode so that all ac
and dc grounded circuit conductors and equipment grounding conductors have the
same near-zero potential to earth.

The GEC to the array was only for the 2008 cycle. Since the NEC isn't a guide for lighting mitigation, the rule was dropped.

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[shortcircuit2]

Well, now I'm totally confused. My inclination is to run my GEC #6 copper to the rails with a WEEB lug and bond the panels and enphase inverter also with a WEEB DMC. Run that down to a grounding rod. Then run the orange Enphase wire along with the two 120vac wires and the common through conduit down to the panel. Connect the enphase orange wire to the bare copper in my panel. Would I be way wrong by doing that?

Your method is OK at the rails with the WEEB system as long as the "RAILS" with the "WEEB" are LISTED and approved as OK for grounding the MODULES. Read the module instruction manual to see what is accepted for grounding methods.

I have not seen an enphase orrange wire. Can you explain this more?

[shortcircuit2]

This open dialog is good…This is my interpretation…Per 2011 NEC:


(3) Combined Direct-Current Grounding Electrode Conductor
and Alternating-Current Equipment Grounding
Conductor. An unspliced, or irreversibly spliced, combined
grounding conductor shall be run from the marked dc grounding
electrode conductor connection point along with the ac
circuit conductors to the grounding busbar in the associated ac
equipment. This combined grounding conductor shall be the
larger of the sizes specified by 250.122 or 250.166 and shall
be installed in accordance with 250.64(E).

The “marked dc connection point” is in the inverter, not at the array. This would be at the string inverter when one is used. With Micro-Inverters this would be up at the array…

[n8huntsman]

Well, now I'm totally confused. My inclination is to run my GEC #6 copper to the rails with a WEEB lug and bond the panels and enphase inverter also with a WEEB DMC. Run that down to a grounding rod. Then run the orange Enphase wire along with the two 120vac wires and the common through conduit down to the panel. Connect the enphase orange wire to the bare copper in my panel. Would I be way wrong by doing that?

[Sunking]

My references were to the 2011 NEC

690.47(D) is gone in 2011

Does not change a thing, this says it all from 2011:

690.47 Grounding Electrode System.

(A) Alternating-Current Systems. If installing an ac system,
a grounding electrode system shall be provided in accordance
with 250.50 through 250.60. The grounding electrode
conductor shall be installed in accordance with 250.64.

(3) Combined Direct-Current Grounding Electrode Conductor
and Alternating-Current Equipment Grounding
Conductor. An unspliced, or irreversibly spliced, combined
grounding conductor shall be run from the marked dc grounding
electrode conductor connection point along with the ac
circuit conductors to the grounding busbar in the associated ac
equipment. This combined grounding conductor shall be the
larger of the sizes specified by 250.122 or 250.166 and shall
be installed in accordance with 250.64(E).

The only thing that changed was John Wiles got his wee-wee smacked for allowing separate GES to be used. Now it got corrected to state both AC and DC systems have to use a common GES. To much crap was getting blown up with separate GES, so it got corrected. The GEC to the panel frames and racking are still sized to 250.66. In 250.66 # 8 AWG Cu or #6AWG Alu. However most all installers use #6 AWG copper to take advantage of leniency allowed by:

250.64 (B) Securing and Protection Against Physical Damage.
Where exposed, a grounding electrode conductor or its enclosure
shall be securely fastened to the surface on which it
is carried. Grounding electrode conductors shall be permitted
to be installed on or through framing members. A 4
AWG or larger copper or aluminum grounding electrode
conductor shall be protected if exposed to physical damage.
A 6 AWG grounding electrode conductor that is free from
exposure to physical damage shall be permitted to be run
along the surface of the building construction without metal
covering or protection if it is securely fastened to the construction;
otherwise, it shall be protected in rigid metal
conduit (RMC), intermediate metal conduit (IMC), rigid
polyvinyl chloride conduit (PVC), reinforced thermosetting
resin conduit (RTRC), electrical metallic tubing (EMT), or
cable armor. Grounding electrode conductors smaller than 6
AWG shall be protected in RMC, IMC, PVC, RTRC, EMT,
or cable armor.

[shortcircuit2]

All this discussion is a moot poin tuntil you know what code cycle th eOP jurisdiction is on. Very few jurisdictions have adopted 2011. I know some still on 1999.

I agree...sorry for the confussion. Here in Massachusetts we adopt the new code on the year it comes out. We haven't driven ground rods for over 2 years according to 690.47(D)...and from the early reviews of the 2014, its not coming back.

[Sunking]

All this discussion is a moot poin tuntil you know what code cycle th eOP jurisdiction is on. Very few jurisdictions have adopted 2011. I know some still on 1999.

[n8huntsman]

This thread discusses something similar: http://www.solarpanelstore.com/forum...c.php?f=5&t=15

[shortcircuit2]

I think Connecticut is on 2005 still...

[sirsparky]

Grounding

You're pretty much on track with you installation grounding plan. The #8 AWG grounding wire that runs from you Inverter to the Service Panel must be continuous. You need to bond it to the AC disconnect (at a grounding bar) but keep it continuous. Don't run two separate wires or the local inspector may call you out on this. This #8 AWG grounding wire can be insulated and should be terminated at the inverter at the terminal ground symbol without the circle. Please call SMA Sunnyboy tech support to confirm this. They will tell you that this conductor is called a GEC.

The ground wire that runs from the Array to the Inverter is an EGC and will be terminated at the Inverter on the terminal ground symbol with the circle.
Again, please call SMA Sunnyboy tech support to confirm this. They will tell you that this conductor is called an EGC.

You should always use grounding bushings where your conduit enters the Inverter, AC disconnect, and also the Service panel if you are using the concentric knockouts. Grounding in Solar is extremely important due to the higher voltage levels involved and most inspectors will really focus on grounding in an installation and sometimes ignore everything else.

Oh yeah - make sure that ALL of your rails and ALL of your panels are grounded bonded to each other and then to the combiner box. Your local jurisdiction may allow you to use WEEBS for the panels but check just to be sure. Inspectors will almost always check to see that your array is properly bonded.

Good luck on your installation!!

[shortcircuit2]

My references were to the 2011 NEC

690.47(D) is gone in 2011

[Sunking]

Naptown...what section 2011NEC regarding grounding electrode conductor to the array and modules?

It is very clear with no doubts:

690.47 Grounding Electrode System.

(A) Alternating-Current Systems. If installing an ac system,
a grounding electrode system shall be provided in
accordance with 250.50 through 250.60. The grounding
electrode conductor shall be installed in accordance with
250.64.

Specifically here is the meat and potatoes.

(D) Additional Electrodes for Array Grounding.
Grounding electrodes shall be installed in accordance with
250.52 at the location of all ground- and pole-mounted
photovoltaic arrays and as close as practicable to the location
of roof-mounted photovoltaic arrays.

That has noting to do with equipment grounding conductor.

[Sunking]

Sunking...I respectfully disagree. The #10 EGC the OP is discussing is for equipment grounding at the array. He did point out that he was using a Sunnyboy 3800 which is a string inverter, and therefore no GEC is needed at the array, only at the inverter.

Sorry but you are just plain wrong. It does not matter if it is string or micro-inverters. The frames of all the PV modules are bonded to a GEC. Micro-Inverters have an additional EGC which is ran with the circuit conductors in the wiring harness.

[shortcircuit2]

Naptown...what section 2011NEC regarding grounding electrode conductor to the array and modules?

[Naptown]

Sunking...I respectfully disagree. The #10 EGC the OP is discussing is for equipment grounding at the array. He did point out that he was using a Sunnyboy 3800 which is a string inverter, and therefore no GEC is needed at the array, only at the inverter.

Wrong all modules and racking must be bonded to the GEC

If he said he was designing a Micro-Inverter type array, then he would need an GEC run to the Array.

Also when you upsize portions of a circuit for voltage drop, you must upsize the equipment grounding conductor also. So just referring to the breaker size, does not allways dictate EGC sizing.

Wrong again see 690.45 A

Running the GEC in conduit is common practice in the industry, but in ferrous raceways there are certain bonding requirements.

shortcircuit

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