grounding question and confusion

[Sunking]

You would optimally want to run the GEC from the panels straight down to earth to a Ground Electrode. Keep in mind the EGC and GEC serve two different purposes.

The EGC purpose is to provide a planned path of low resistance to clear line faults. For example if either L1 or L2 were to short to the metallic case of the inverter, the fault current would be routed directly to the neutral conductor (grounded circuit conductor). The fault current will be very high, thus operating the over current protection device (aka fuse or breaker)

The GEC purpose is two fold but its primary purpose is to provide a low resistance path for high voltage directly to earth to be discharged. High voltages would be lightning or over head high voltage utility lines that might fall on the panels. You do not want to route that through your equipment or your home wiring.

[n8huntsman]

That makes more sense. Since the enphase is converting DC to AC, is the green wire in the engage cable the GEC from the DC side? It also says to run the GEC through PVC. So you would run the pvc right alongside the EMT containing the common and hot wires?

[Sunking]

The codes are extremely complex and generally not well understood by the public at large so please refrain in the future from advising people how to interpret the codes.

That is why I usually refrain from even answering.

FWIW Mike Holt is probable one of the most knowledgeable person in the USA on NEC codes. He makes his living teaching code to engineers and electricians alike. I am a moderator on his Code Forum for grounding, low voltage and solar. Mike was published in ECM on the NEC changes with respect to 690 you might want to read as it highlights the recent changes. Most notable combining DC and AC GEC. However it is still required to bond the PV frames and racking directly to a GES with a dedicated GEC. f you stop and think about it makes perfect sense. Why would you want to dire a direct lighting strike through all your equipment, and into your AC panel. That would be nucking futs.

Source here

[n8huntsman]

I agree, and ultimately I will contact the building dept. As an owner builder I like to understand the different methods before contacting them because they tend to not want to talk to clueless people. It's been my experience that if I sound familiar with the concepts, they will work with me, tell me what they want to see, and actually let me slip on some things if it's not exactly perfect. Happend a couple times when I built my pool. I did not have a continuous bond wire from the rebar in the pool, to the rebar in the concrete and back to the ground rod. Instead I had a bare copper wire from the ground rod to the rebar in the concrete deck, then three feet away I another piece from the concrete deck to the pool rebar, not one continuous wire. They said, "Oh well. Too late now since your gunite guys are coming tomorrow."

[Naptown]

What we are having is a conundrum. Because of differing adoptions of the various code books and local amendments changing further, not to mention interpretations of the codes by AHJ's It would be best to not offer advice on a forum pertaining to codes. They are different everywhere even when the same code is applied due to issues as stated above. What works for me in Maryland may not necessarily be to code in Massachusetts.
The only advice that would be valid would be to consult with the AHJ in your jurisdiction. Keep in mind that this is a forum open to everyone on the planet with the exception of a few hundred thousand spammers. The codes are extremely complex and generally not well understood by the public at large so please refrain in the future from advising people how to interpret the codes.

[shortcircuit2]

So for 2011, we can bring the GEC (#6 typically) into the on roof j-box and attach it to the EGC (green wire) from the enphase cable? Run a single wire back to the panel ground bar.

The GEC must continue thru the roof box unbroken to the micro inverters...each one. Or if the racking is listed and approved as suitable for intergrounding with the modules, you can just hit the rails that the inverters are bolted to. If wiring as a combo GEC/EGC you must terminate in the roof box also with the equipment grounds from the Enphase cable. Ferrous raceways must be bonded at both ends. Its not easy when doing it this way.

And yes the rule is to bring it back to the panel ground bar when following combo rules. In Mass. the combo rule is not accepted by the CEC FIT program.

[shortcircuit2]

690.43 says an EGC has to connect to module frames and equipment. This IS in 2005, 2008 and the 2011NEC...

[shortcircuit2]

I wouldn't call it purty but it is very easy to understand. At least I understand

Where is the equipment grounding conductor connection to the array in those diagrams???

[n8huntsman]

So for 2011, we can bring the GEC (#6 typically) into the on roof j-box and attach it to the EGC (green wire) from the enphase cable? Run a single wire back to the panel ground bar.

[SunEagle]

I like pictures. Do you like pictures?

I am kind of slow and stupid and I like purty pictures to describe things.

I wouldn't call it purty but it is very easy to understand. At least I understand

[shortcircuit2]

I like pictures. Do you like pictures?

I am kind of slow and stupid and I like purty pictures to describe things.

That isn't reflecting what the 2011 or the 2005 NEC says. The diagram also only depicts a system with a isolation type string inverter.

Grounding would be different in an ungrounded system connected to a non-isolated type inverter.

[Sunking]

I like pictures. Do you like pictures?

I am kind of slow and stupid and I like purty pictures to describe things.

[shortcircuit2]

"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 always dictate EGC sizing."

Wrong again see 690.45 A

Naptown..You are right on this one according to the 2011NEC and this was new in 2008 because they realized the fault current is only what is avaiable from the array.

In 2005 it was aliitle different...

690.45 Size of Equipment Grounding Conductor
Where not protected by the ground-fault protection equipment required by 690.5, the
equipment-grounding conductor for photovoltaic source and photovoltaic output circuits
shall be sized for 125 percent of the photovoltaic-originated short-circuit currents in that
circuit. Where protected by the ground-fault protection equipment required by 690.5, the
equipment-grounding conductors for photovoltaic source and photovoltaic output circuits
shall be sized in accordance with 250.122.

But in 2005 you still had to upsize according to 250.122(B)

(B) Increased in Size Where ungrounded conductors are increased in size, equipment
grounding conductors, where installed, shall be increased in size proportionately
according to circular mil area of the ungrounded conductors.

Commentary in 2005 NEC:

In systems where a ground-fault protection device according to 690.5 is not used, and
the circuit conductors are oversized for voltage drop, the requirements of 250.122(B)
must be followed.
Some PV systems (primarily utility-interactive) with ground-fault protection devices
do not require overcurrent devices in the PV source or output circuits, and 250.122
cannot be used to size the equipment grounding conductors. In these cases, the
equipment grounding conductor for a PV source or output circuit should be sized at
least 125 percent of the PV-originated short-circuit current in that circuit.

shortcircuit

[shortcircuit2]

Here is where I was getting orange: http://enphase.com/wp-uploads/enphas...ngle_Phase.pdf
I assume this is the bare copper wire that would go to the ground in the panel?

That plan is 4 years old and the orange isn't used. GREEN is for ground here in the States. The most popular Enphase inverter in residential use is the M215 currently and the AC interconnect cable has BLACK, RED, WHITE, and GREEN...no orange that I have seen. The orange may be for 3/phase systems to balance the system.

[n8huntsman]

Here is where I was getting orange: http://enphase.com/wp-uploads/enphas...ngle_Phase.pdf
I assume this is the bare copper wire that would go to the ground in the panel?