connecting EGC and neutral for a line side tap (supply side connection)

[jaggedben]

In my case, I really don't care all that much. It's a bit simpler/cheaper just to run the EGC back to the service rather than establishing a new GEC on the other side of the split and bonding it to the existing electrode, but it's not a big deal. A case for compliance can be made either way..

I've come around to view it pretty much the same way, which is why I didn't propose that change to the service definition last time around.

There is one type of case I've seen where it really does make a difference, and could really suck if you didn't get on the same page as your AHJ before you started install. That's where your (large) inverter doesn't require a neutral. In that case you'd like to argue that the PV disconnect is not a service disconnect so that you don't have to bring a neutral to it according to 250.24(C). Or at least you'd like your AHJ to accept that it's safe regardless of what terms you use. The neutral itself could cost a lot of money if it's large and long, but what would cost more is if you made your conduit too small before asking your AHJ if they would require it.

 

[c_picard]

Perhaps some of the more experienced electricians can educate the crowd on why a neutral needs to be bonded to each service enclosure in the first place, without PV?

Then follow with an explanation of how those concerns would disappear once we connect an inverter to the load-side terminals.

 

[jaggedben]

Some see it that way, but note Part IV title is Service Equipment — Disconnecting Means. If the disconnect is not service equipment, i.e. a service disconnecting means, then 230.70 does not apply.

As I pointed out above, 230.70 is written to apply to service entrance conductors, regardless of whether you consider them connected to a service. Service entrance conductors, by definition, are between the service conductors and the service equipment. Service conductors, by definition, are between the service point and the service entrance conductors. The service point, by definition, exists if there is a utility connected to the building.

All these terms logically apply even if you say that none of them, by definition, are part of a 'Service.' :happyyes: That's right: logically, by literal application of definitions, you can have service conductors, service entrance conductors, service equipment, and service disconnecting means, but no service. No contradiction.

I'll just add that I ultimately don't really truck with this notion of 'the code says what it says', as if it is logically consistent throughout and doesn't contradict itself. It isn't consistent and it contradicts itself. After all, it's written by humans.

 

[Smart $]

As I pointed out above, 230.70 is written to apply to service entrance conductors, regardless of whether you consider them connected to a service. Service entrance conductors, by definition, are between the service conductors and the service equipment. Service conductors, by definition, are between the service point and the service entrance conductors. The service point, by definition, exists if there is a utility connected to the building. ...

A stretch to some, but I'm just putting it out there for speculation, because as I said earlier, the disconnect must be service equipment for 230.70 to apply.

As far as one-line diagrams go, the PV service entrance conductors are between the service point and the service equipment... at least at the point where they receive utility power.

 

[SolarPro]

It isn't consistent and it contradicts itself. After all, it's written by humans.

Worse, yet. It's written and edited by people on committees who have about 5 minutes to spend on each item. It's a wonder it makes any sense at all.

 

[Carultch]

A stretch to some, but I'm just putting it out there for speculation, because as I said earlier, the disconnect must be service equipment for 230.70 to apply.

As far as one-line diagrams go, the PV service entrance conductors are between the service point and the service equipment... at least at the point where they receive utility power.

What exactly is "service equipment"?
Main Disconnect?
Meter?
Panelboard with main breaker acting as service disconnect?
All of the above?

Because in the event that you have an existing hot-sequence metered service, you might interconnect the PV between the main service disconnect and the main service meter. It still gets measured as if it is part of the same service as the existing loads, yet it would have its own "service" disconnect (open to interpretation).

 

[GoldDigger]

JMO:
Nowhere does the NEC say that a supply side PV disconnect is or is not a service disconnect.
It just says that the equipment used as the PV disconnect does not have to be listed for use as a service disconnect.
Which various people interpret in different ways.

 

[c_picard]

JMO:
Nowhere does the NEC say that a supply side PV disconnect is or is not a service disconnect.
It just says that the equipment used as the PV disconnect does not have to be listed for use as a service disconnect.
Which various people interpret in different ways.

There are several legitimate and thoughtful comments in this thread that illustrate how the NEC has a gap in coverage for some on this topic. Stating that the PV disconnect doesn't need to be listed as service equipment isn't one of them. With all respect, it's just flat out false, and certainly isn't going to move the conversation forward. Calling the disconnect used for a supply-side connection the "PV disconnect" is a misleading and inappropriate use of the term. This error has been pointed out over and over; 690.13(C) is addressing the DC side of the system.

We should all be able to agree this piece of equipment needs to be called something. Let's start with 'disconnecting means' and go from there? Or is there someone that doesn't feel the Code gives us a clear path to calling something that opens a circuit a disconnecting means?

 

[c_picard]

Back to the OPs question, consider this another way. It doesn't matter what we choose to call the flippy-offy-thingy...

250.24(B) "...for each service disconnect in accordance with 250.28."

250.28(D)(2) "Where a service consists of more than a single enclosure as permitted in 230.71(A)..."

230.71(A) "The service disconnecting means for each set of service entrance conductors permitted by 230.40, Exception No. 5" (Deleted irrelevant words for clarity, because grammar).

230.40, Exception 5 "One set of service-entrance conductors shall be permitted to supply systems covered by 230.82(6)." (Again, deleted words for clarity)

It won't hurt my feelings if folks still refuse to call this a service disconnect. If you work for me, put in the green screw, and to the OP if he/she hasn't quit the forum yet, if you're in NYSERDA land..put in the green screw.

iwire had a great comment earlier about approaching Code language from different perspectives. Very poignant observation, I would just add that in this case no one is really asking the Code to bend to fit PV; it already fits as-is. If we take the time to understand the root hazard being addressed, the language is adequate.

 

[iwire]

An exporting PV system doesn't stop utility power from being connected to the building. If the definition said 'power' instead of 'energy' then there would be no debate.

Power, energy, coconuts, whatever you want to call it does not change things.

Also you realize that from a person's point of view, first responder or electrician or whoever, it makes no difference, right?

Actully IMO it makes a big difference one that is a safety issue.

 

[c_picard]

I think you will find in upstate NY working through NYSERDA on a supply side connection they want neutral to ground bond on the AC disco. Thus, making your former main panel a sub.

Regardless of anything else said in this thread, this is probably the most incorrect. The main stays a main. Yikes.

 

[Carultch]

Actully IMO it makes a big difference one that is a safety issue.

Very true. This is not one of those cases where one should overbuild when in doubt. Such as the example of, "I'm not sure if this is 'subject to physical damage' or not, so I'm just going to overbuild out of ignorance, assuming it is subject to physical damage."

Bonding the ground and neutral is a situation where overbuilding out of ignorance, can be counterproductive to safety. When you do it more than necessary, it creates a parallel path among the conductor that should intentionally carry current, and the non-current-carrying conductive materials. The neutral should be carrying the neutral current, and not sharing that job with the EGC, enclosure walls, metal conduit, and building steel. Because any serious neutral current, needs to be carried on the wire sized for it, and not on metallic compoents that a person could touch accidentally.

That is why it is required to only bond the neutral and ground at code-required locations, and leave them isolated where not required. One point = no parallel paths. Multiple points = paths in parallel with the neutral.

In my opinion, the place where it makes most sense to do this, is at the transformer secondary. This is where you define the part of the system to be at zero volts-to-ground, by grounding the conductor we call neutral. This is the part where the circuit is isolated from the other circuits on the utility network, and is otherwise free to "float" to a different absolute voltage level if it isn't grounded.

 

[Smart $]

What exactly is "service equipment"?
Main Disconnect?
Meter?
Panelboard with main breaker acting as service disconnect?
All of the above?
...

All the above and then some, although 230.66 says a meter socket shall not be considered service equipment... yeah, right? :sarcasm: (rhetorical)

Take the Aticle 100 definitions of Service and Equipment and combine them together. 230.66 also requires all service equipment under 1000V to be listed. What about service conductors and associated wiring method parts? They're service equipment, right?

 

[jaggedben]

Power, energy, coconuts, whatever you want to call it does not change things.

If words don't matter, then why do you even have an opinion (post #31) as to whether it should be called a service disconnect?

Power and energy are different things and the definition of a service refers to one of them and not the other, and supply side PV disconnect does connect one of them and not the other.

Actallly IMO it makes a big difference one that is a safety issue.

You're going to have to explain what you mean by that, because to me in all safety respects the PV disconnect is exactly like a service disconnect.

 

[jaggedben]

A stretch to some, but I'm just putting it out there for speculation, because as I said earlier, the disconnect must be service equipment for 230.70 to apply.

You're basically just bolstering my underlying point, which is that cherrypicking the wording of some code sections leads to interpretations that are, really, rather ridiculous.

 

[jaggedben]

...Take the Aticle 100 definitions of Service and Equipment and combine them together. ...

Actually it's probably more appropriate to just take the Article 100 definition of 'Service Equipment'. There is one, after all.

 

[jaggedben]

Very true. This is not one of those cases where one should overbuild when in doubt. Such as the example of, "I'm not sure if this is 'subject to physical damage' or not, so I'm just going to overbuild out of ignorance, assuming it is subject to physical damage."

Bonding the ground and neutral is a situation where overbuilding out of ignorance, can be counterproductive to safety. When you do it more than necessary, it creates a parallel path among the conductor that should intentionally carry current, and the non-current-carrying conductive materials. The neutral should be carrying the neutral current, and not sharing that job with the EGC, enclosure walls, metal conduit, and building steel. Because any serious neutral current, needs to be carried on the wire sized for it, and not on metallic compoents that a person could touch accidentally.

That is why it is required to only bond the neutral and ground at code-required locations, and leave them isolated where not required. One point = no parallel paths. Multiple points = paths in parallel with the neutral.

In my opinion, the place where it makes most sense to do this, is at the transformer secondary. This is where you define the part of the system to be at zero volts-to-ground, by grounding the conductor we call neutral. This is the part where the circuit is isolated from the other circuits on the utility network, and is otherwise free to "float" to a different absolute voltage level if it isn't grounded.

Please explain how a disconnect for an interactive PV inverter(s) presents any different problems from an additional service disconnect for a permitted load. I would submit that they are no different with respect to any safety principle. The code generally requires bonding the neutral to ground at all service disconnects and does not regard any parallel paths thus created as a problem per se.

 

[Smart $]

Actually it's probably more appropriate to just take the Article 100 definition of 'Service Equipment'. There is one, after all.

Yes, and the word equipment is used within that definition... and guess what? There is a definition for Equipment, after all. :angel:

 

[Smart $]

You're basically just bolstering my underlying point, which is that cherrypicking the wording of some code sections leads to interpretations that are, really, rather ridiculous.

Nobody cherry picking any wording on this end. :huh::blink:

As I mentioned in that other thread you linked to earlier, you really are one to take things way out of context.

 

[ggunn]

Very true. This is not one of those cases where one should overbuild when in doubt. Such as the example of, "I'm not sure if this is 'subject to physical damage' or not, so I'm just going to overbuild out of ignorance, assuming it is subject to physical damage."

Bonding the ground and neutral is a situation where overbuilding out of ignorance, can be counterproductive to safety. When you do it more than necessary, it creates a parallel path among the conductor that should intentionally carry current, and the non-current-carrying conductive materials. The neutral should be carrying the neutral current, and not sharing that job with the EGC, enclosure walls, metal conduit, and building steel. Because any serious neutral current, needs to be carried on the wire sized for it, and not on metallic components that a person could touch accidentally.

That is why it is required to only bond the neutral and ground at code-required locations, and leave them isolated where not required. One point = no parallel paths. Multiple points = paths in parallel with the neutral.

Point. Consider a PV system on a three phase service consisting of three inverters of unequal size connected phase to neutral, interconnected on the supply side. Because of the unbalanced nature of the system there would be current on the neutral, wouldn't there? It seems to me that bonding neutral to ground at the disco would put current on the ground between the disco and the point of interconnection.