Neutral for circuits micro inverters

[Smart $]

Thank you.

I knew it was required somewhere and I even looked in 408 and somehow missed it. Too bad there was so much noise on this thread before arriving at the right answer.

That section doesn't actually say anything about dedicated neutrals returning all the way as such to the panel... as opposed to a common neutral returning to the panel. All that section truly says is that you can only land one grounded conductor per terminal... except parallel neutrals, provided the terminal is identified for more than one conductor.

 

[shortcircuit2]

200.4(A) requires a neutral to be used for only 1 circuit.

300.3(B) requires conductors of the same circuit to be run together.

408.41 requires the neutral to terminate in the panelboard.

300.3(B)(4) is the only exception to 408.41

These Code sections make the OP idea a violation.

 

[Smart $]

200.4(A) requires a neutral to be used for only 1 circuit.

300.3(B) requires conductors of the same circuit to be run together.

408.41 requires the neutral to terminate in the panelboard.

300.3(B)(4) is the only exception to 408.41

These Code sections make the OP idea a violation.

While you make it sound convincing, those sections do not actually specify the "idea" as a violation.

200.4(A) is certainly the most convincing. It says a neutral conductor shall not be used for more than one branch circuit, one mwbc, or one set of feeder conductors. But to be absolute, you have to have a section which says a branch or feeder circuit neutral must land in the same enclosure as its ungrounded counterpart(s). BTW, a feeder neutral commonly supplies more than one branch circuit neutral all the time in premises wiring. So without more context in that section, it can pretty much be interpreted the way the person interpreting it wants to interpret it.
(How's that for using redundant wording )

Whether common or dedicated, all the conductors of the same circuit are run together, so no go on 300.3(B).

And I already pointed out the flaw in 408.41 above.

 

[jaggedben]

And if you would read the posts for what they truly say, and participate rather than try to steer the discussion in the direction you want it to go, we might actually get somewhere. That said, if you read my post, you'd realize the code section you already quoted* does not apply in the case of line-to-neutral microinverter system. Then again, perhaps you will not realize it. We shall see.

*You didn't actually quote it; you cited a reference to it,

Look, I made a parenthetical statement, which was factual and cited a relevant code section, in case anyone wanted to educate themselves about it. You questioned whether my statement was factual without evidently looking up the code section to educate yourself. Of course I was already aware that the code section does not apply in the case of line-neutral inverter connections, but such connections are relatively rare, which is why I made the statement in the first place. My statement was and still is factual, as another person (ggunn) explained on my behalf.

 

[jaggedben]

200.4(A) requires a neutral to be used for only 1 circuit.

300.3(B) requires conductors of the same circuit to be run together.

408.41 requires the neutral to terminate in the panelboard.

300.3(B)(4) is the only exception to 408.41

These Code sections make the OP idea a violation.

I agree with this 100%. You didn't mention 215.4 which allows a common neutral for feeders, but I think the chances that the OP is talking about feeders and not branch circuits are very small.

 

[Smart $]

Look, I made a parenthetical statement, which was factual and cited a relevant code section, in case anyone wanted to educate themselves about it. You questioned whether my statement was factual without evidently looking up the code section to educate yourself. Of course I was already aware that the code section does not apply in the case of line-neutral inverter connections, but such connections are relatively rare, which is why I made the statement in the first place. My statement was and still is factual, as another person (ggunn) explained on my behalf.

Parenthetical is just another way of saying you branch slightly off topic at your discretion without notifying anyone. You cited a Code section relevant to your topic... not the thread topic. I did not question whether your statement was factual. I questioned your statement being applicable to the thread topic. I didn't have to look up the section. I was sitting there with it already displayed in the adjacent window.

Whether rare or not, the thread title is "Neutral for circuits micro inverters". For everyone's sake, please stay on topic and stop confusing the issue at hand.

 

[shortcircuit2]

While you make it sound convincing, those sections do not actually specify the "idea" as a violation.

True, any idea is not a violation. But install that "idea" in the field that is restricted by the Code and it becomes a violation.

200.4(A) is certainly the most convincing. It says a neutral conductor shall not be used for more than one branch circuit, one mwbc, or one set of feeder conductors. But to be absolute, you have to have a section which says a branch or feeder circuit neutral must land in the same enclosure as its ungrounded counterpart(s).

300.3(B) will take the neutral circuit wiring to the enclosure (panelboard) and 408.41 says where to land the neutral and how. A feeder neutral has to end at the enclosure (panelboard) with the final branch-circuit overcurrent devices.

BTW, a feeder neutral commonly supplies more than one branch circuit neutral all the time in premises wiring.

True, this is allowed by 215.4 and 200.4(A).

So without more context in that section, it can pretty much be interpreted the way the person interpreting it wants to interpret it.
(How's that for using redundant wording )

I disagree. It can only be interpreted as written. 200.4(A) makes the OP idea a violation of the Code if installed in the field.

 

[Smart $]

...
I disagree. It can only be interpreted as written.
...

As you can plainly see, even "interpreted as written" can result in different interpretations. Ultimately, the only interpretation that matters is that of the project AHJ.

 

[mryan]

Thank you

 

[jaggedben]

Parenthetical is just another way of saying you branch slightly off topic at your discretion without notifying anyone. You cited a Code section relevant to your topic... not the thread topic. I did not question whether your statement was factual. I questioned your statement being applicable to the thread topic. I didn't have to look up the section. I was sitting there with it already displayed in the adjacent window.

Whether rare or not, the thread title is "Neutral for circuits micro inverters". For everyone's sake, please stay on topic and stop confusing the issue at hand.

I'm not interested in continuing this discussion, except to say that I think 705.95(B) is extraordinarily relevant to the topic, especially if one thinks that the combined neutral is not a violation. For the record, I think it's a violation, although not one with any safety consequence if the neutral qualifies under 705.95(B). And, I hope you've learned something about how most microinverters are connected, i.e. line-line.

 

[Smart $]

I'm not interested in continuing this discussion, except to say that I think 705.95(B) is extraordinarily relevant to the topic, especially if one thinks that the combined neutral is not a violation. For the record, I think it's a violation, although not one with any safety consequence if the neutral qualifies under 705.95(B). And, I hope you've learned something about how most microinverters are connected, i.e. line-line.

:slaphead:
I see you opened up your reply with a contradicting remark from the get go. If you were truly "not interested in continuing this discussion", you would have stopped at the end of that remark.

Here, let me show you how it is done...

I have no interest in continuing this discussion.

 

[pv_n00b]

I agree with this 100%. You didn't mention 215.4 which allows a common neutral for feeders, but I think the chances that the OP is talking about feeders and not branch circuits are very small.

While I am sure this is opening up another bag of arguments, there are no branch circuits in PV systems except for those powering ancillary equipment in large systems.

From the NEC:

Branch Circuit. The circuit conductors between the final
overcurrent device protecting the circuit and the outlet(s).

Branch circuits supply power to outlets, lights, and utilization equipment but not power sources.

Feeder. All circuit conductors between the service equipment,
the source of a separately derived system, or other
power supply source and the final branch-circuit overcurrent
device.

So the referenced code sections that prevent a common neutral for branch circuits do not apply.

 

[ggunn]

While I am sure this is opening up another bag of arguments, there are no branch circuits in PV systems except for those powering ancillary equipment in large systems.

From the NEC:

Branch Circuit. The circuit conductors between the final
overcurrent device protecting the circuit and the outlet(s).

Branch circuits supply power to outlets, lights, and utilization equipment but not power sources.

Feeder. All circuit conductors between the service equipment,
the source of a separately derived system, or other
power supply source and the final branch-circuit overcurrent
device.

So the referenced code sections that prevent a common neutral for branch circuits do not apply.

So what would you call a circuit that has several microinverters in parallel on it and which terminates in a 2P-20A breaker in an AC combiner panel? It's certainly not a "string", since its comprising elements are not in series. I attended an advanced PV design class a couple of weeks ago taught by a senior master electrician, and he referred to such circuits as branch circuits, as do I in the systems I draw.

 

[Smart $]

Refer to Figure 690.1(a). Dubbed therein as "Dedicated branch circuit of the electric production and distribution network".

 

[jaggedben]

While I am sure this is opening up another bag of arguments, there are no branch circuits in PV systems except for those powering ancillary equipment in large systems.

From the NEC:

Branch Circuit. The circuit conductors between the final
overcurrent device protecting the circuit and the outlet(s).

Branch circuits supply power to outlets, lights, and utilization equipment but not power sources.

Feeder. All circuit conductors between the service equipment,
the source of a separately derived system, or other
power supply source and the final branch-circuit overcurrent
device.

So the referenced code sections that prevent a common neutral for branch circuits do not apply.

If the words in bold can be conjectured from the definition then inverters can, too. Or maybe they are just another category of 'utilization equipment.'

More importantly, shortcircuit's logic still applies as long as the inverter circuits are not 'feeders'.

 

[ggunn]

Refer to Figure 690.1(a). Dubbed therein as "Dedicated branch circuit of the electric production and distribution network".

IOW, a branch circuit.

 

[pv_n00b]

So what would you call a circuit that has several microinverters in parallel on it and which terminates in a 2P-20A breaker in an AC combiner panel? It's certainly not a "string", since its comprising elements are not in series. I attended an advanced PV design class a couple of weeks ago taught by a senior master electrician, and he referred to such circuits as branch circuits, as do I in the systems I draw.

I would call it the same thing we call the circuit from a string inverter where the AC output terminates at a 2P-20A breaker, an inverter output circuit. This figure is the only thing in the NEC that describes an inverter output circuit as a branch circuit, so I think it's a little weak to support the idea that the NEC has defined this as a branch circuit.

Inverters are not utilization equipment. From 100:

Utilization Equipment. Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.

Inverters are primarily an energy source, not a load. Branch circuits power loads, if it's not a load it's not a branch circuit.

 

[ggunn]

I would call it the same thing we call the circuit from a string inverter where the AC output terminates at a 2P-20A breaker, an inverter output circuit. This figure is the only thing in the NEC that describes an inverter output circuit as a branch circuit, so I think it's a little weak to support the idea that the NEC has defined this as a branch circuit.

Inverters are not utilization equipment. From 100:

Utilization Equipment. Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.

Inverters are primarily an energy source, not a load. Branch circuits power loads, if it's not a load it's not a branch circuit.

For my purposes it's a branch circuit.

 

[jaggedben]

I think we're officially off-topic, unless anyone wants to argue that the inverter output circuit is a feeder for the purposes of invoking 215.4. If not, then the OP can't run a common neutral.

Very interesting discussion on what is a branch circuit, and I agree with ggunn, but my use of it above was ultimately incidental to the point being made.

 

[shortcircuit2]

The directions for Enphase micro-inverters call it a Branch Circuit many times in the paperwork included with the product.

I see it as a 2-way circuit...its an Inverter Output Circuit going towards the utility supply and a Branch Circuit going towards the Inverter. And in the direction from utility to inverter the circuit is a Branch Circuit and subject to the rules as applied for branch circuits.

So look at the specs here...

http://www.enphase.com/sites/default/files/M215_DS_EN_60Hz.pdf

See how the nighttime power consumption is "65mW max"...well that makes the micro-inverter an Outlet by definition in the Code.

Actually, all inverters use some power at nighttime and should be considered an Outlet and Utilization Equipment by the Code, I do.

shortcircuit