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diy solar

Confused by array grounding

No. The coil on the primary side of the transformer has no neutral. Only the secondary side has a neutral (which is grounded) The service drop to a residence has two hots (ungrounded conductors) and a neutral. Since it is grounded the NEC refers to the neutral as a (grounded conductor. The main disconnect panel is where all grounds and neutrals are connected by a bonding jumper, ie. at the first point of disconnect. All other panels connected with this panel must have grounds and neutrals separated. Also non-current carrying conductive equipment within this service must be bonded to ground with an equipment grounding conductor.

This is per my understanding.
 
FilterGuy said:
That is correct. This bond is called the System bonding jumper

That is also correct. This bond is called the Main bonding jumper.

The reason the bond at the utility transformer is not sufficient is that in the US the utility does not provide an independent ground wire. It only provides the two hots and the Neutral. This means the neutral-ground bond has to be re-established on the customer premise in order to have a low impedance path for ground faults.




What it is called can be an interesting conversation.... but how it is wired in the US is not debatable.

As I stated above, the neutral coming from the utility is tied to earth ground at the utility transformer and it is also tied to earth ground at the first means of disconnect on the customer premise. Having said that, I do not know for sure what it is called.

The System bonding Jumper does not provide a low-impedance path for ground faults so it is not providing one of the intended purposes of a grounded conductor. However, once the Main bonding jumper is in place, it certainly becomes a grounded conductor.

The other bit of trivia that throws in a question mark is that the NEC explicitly states that it does not cover the Utility. As such, does the NEC term "Grounded Conductor" apply to a wire that is part of the Utility?
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I believe the neutral which is on the secondary side of a transformer is connected to ground at the pole or ground transformer, so it is grounded before becoming your service drop.
 
Pilot Bob said:
No. The coil on the primary side of the transformer has no neutral. Only the secondary side has a neutral (which is grounded)
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That depends on the service and the grid available.
At the end of a residential area. It's not uncommon for the available grid to be only a single leg and a neutral.
Which is what feeds the transformer.
Pilot Bob said:
I believe the neutral which is on the secondary side of a transformer is connected to ground at the pole or ground transformer, so it is grounded before becoming your service drop.
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It is connected to earth, at the transformer.
 
Pilot Bob said:
The coil on the primary side of the transformer has no neutral. Only the secondary side has a neutral (which is grounded)
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Some of the utility transformers are configured wye-wye (IIRC primarily for pole mount). Many residential installations (especially rural) carry only a single phase and no neutral, using the earth as the return path.
 
Zwy said:
Do as you wish but it wouldn't pass inspection or be safe.

As Tim stated, put up a tall fence with warning signs so other people can't be hurt or killed by your decision.
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Haaaaa….that’s funny…
J.
 
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scoharri said:
Lots of great stuff here. So what is the case for PV ground mount grounding when its totally off grid?
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Same as it is on gird, the PV ground mount and panel is bonded to the ground system at the home/building severed
 
Watts Happening said:
Again I’m not against it, I’ll be bonding mine to my main panel. The arguments for needing it just seem rather unlikely. I’m sure there are more convincing ones, but personally the lightning one seems outlandish.

A ground array is by definition grounded, to what degree can be argued no doubt. But I’ve seen lightning bolts blow though 100 foot tall trees, they’re not exactly worried about conductivity. I also think it’s a bit foolish to think a 6-12awg conductor is somehow harnessing that power lol
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The equipment grounding being discussed is completely different from Lighting Protection. There is no cross compatibility or sharing of materials.
 
timselectric said:
It's whatever the utility wants to call it.
In my area, they call it a neutral or common. But, that can change tomorrow.
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The Poco is governed by the National Electric Service Code, I’m sure they way they construct their power delivery systems, pole/ground mounted transformers, service wiring etc. is described therein and everything has assigned nomenclature.
 
Great discussion. I have a similar setup except that my array is on the roof of a barn 100 feet from the house main panel.
I learned here that I need to run an EGC from the array to the inverter which is in the house near the main panel. My question is what awg should the ground be? I know that anywhere it is exposed it must be at least #6, but what about inside the trench/conduit? I think the consensus here is that even #6 won't protect against lightning so we are really grounding the panels from shorts. I am running #10 for + and - so shouldn't that be enough for ground as well? (Maybe even smaller based on amperage). Even though I have 4 separate strings of 10 amps each, my thinking is that #10 should still be ok for all 4 since it would be unlikely for more than one fault to occur.
 
lapsmith said:
Great discussion. I have a similar setup except that my array is on the roof of a barn 100 feet from the house main panel.
I learned here that I need to run an EGC from the array to the inverter which is in the house near the main panel. My question is what awg should the ground be? I know that anywhere it is exposed it must be at least #6, but what about inside the trench/conduit? I think the consensus here is that even #6 won't protect against lightning so we are really grounding the panels from shorts. I am running #10 for + and - so shouldn't that be enough for ground as well? (Maybe even smaller based on amperage). Even though I have 4 separate strings of 10 amps each, my thinking is that #10 should still be ok for all 4 since it would be unlikely for more than one fault to occur.
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#10 is more than adequate. With 10a OCP, #14 is large enough.
 
Took the whole day to fish the wires through the conduit and cover up the trench to the barn, but it is done and the #14 awg EGC is in the conduit along with the +/- back to the house main panel.

I know there has been debate in this thread about having a grounding rod at the array, but I think that was in lieu of running an EGC back to the main panel. Since I now have an EGC running from the array to the main panel, is there any benefit to adding a ground rod near the array? Would it create a ground loop? Would it improve, or possibly worsen lightning protection?
 
Thanks Timselectric. I like answers that mean less work:)

This brings up another somewhat related question and hopefully my last. The barn where the solar array will be has a 200 amp sub panel coming from the main house with (what looks like) a #6 ground wire. It also a grounding rod in addition to the one at the house. Based on our discussion, it seems like I'd be better off just disconnecting that ground rod? Or is this a different animal? I know previous posts have said that NEC keeps waffling on this so maybe it was required 4 years ago when it was built.
 
lapsmith said:
Thanks Timselectric. I like answers that mean less work:)

This brings up another somewhat related question and hopefully my last. The barn where the solar array will be has a 200 amp sub panel coming from the main house with (what looks like) a #6 ground wire. It also a grounding rod in addition to the one at the house. Based on our discussion, it seems like I'd be better off just disconnecting that ground rod? Or is this a different animal? I know previous posts have said that NEC keeps waffling on this so maybe it was required 4 years ago when it was built.
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An auxiliary ground rod is still in the code, currently. For separate buildings and structures. So, the code still requires that ground rod. Because of this, I can't tell you to disconnect it.
All that I can say is that I would.
The code is continuously changing. 40 years ago, we didn't run a EGC or add a rod. 20 years ago, you were required to do one or the other. But never both.
Currently, both are required. Hopefully soon, they will drop the requirement for the rod. And just require the EGC. Because it creates more problems than it solves.
 
timselectric said:
The code is continuously changing. 40 years ago, we didn't run a EGC or add a rod. 20 years ago, you were required to do one or the other. But never both.
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I think my old boss was responsible for one of those changes. He was of the "ground the hell out of it" school, and some of his damage persists.

It is interesting though that depending on the type of building and structure the optimal solution can change significantly. Too much focus on one type or another skews good practice.
 
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