Article 230.40 as it relates to solar

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Hi,

I just wanted some clarification on understanding Article 230.40, Exception #5, as well as Article 230.71 of the NEC 2014.

Article 230.40, Exception #5, states, "One set of service-entrance conductors connected to the supply side of the normal service disconnecting means can supply standby power systems, fire pump equipment, and fire and sprinkler alarms [230.82(5)] as well as Solar PV systems [230.82(6)]".

I guess I should also mention the orignial article, Article 230.40 which states, "Each service drop, service lateral, or set of underground or overhead service conductors may only supply one set of service-entrance conductors".

Things that I'm thinking:

--How could service-entrance conductors supply power to a PV system, or any other standby power supply? Doesn't a standby power supply.... supply non-utility power?

--How is this considered an exception? It sounds pretty close to the parameters of the original article.

Thank you reading!

Kind Regards,
Andy
 
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shortcircuit2

Senior Member
Location
South of Bawstin
Hi,

I just wanted some clarification on understanding Article 230.40, Exception #5, as well as Article 230.71 of the NEC 2014.

Article 230.40, Exception #5, states, "One set of service-entrance conductors connected to the supply side of the normal service disconnecting means can supply standby power systems, fire pump equipment, and fire and sprinkler alarms [230.82(5)] as well as Solar PV systems [230.82(6)]".

I guess I should also mention the orignial article, Article 230.40 which states, "Each service drop, service lateral, or set of underground or overhead service conductors may only supply one set of service-entrance conductors".

Things that I'm thinking:

--How could service-entrance conductors supply power to a PV system, or any other standby power supply? Doesn't a standby power supply.... supply non-utility power?

--How is this considered an exception? It sounds pretty close to the parameters of the original article.

Thank you reading!

Kind Regards,
Andy

The Code is using the word SUPPLY as a verb as related to your concern..."to supply" or " to connect" ...not as a noun as in "supply side or "power supply".
 
Thanks for your repsonse. However, I was reading "supply" as a verb when I posed the question. After doing some research on the Internet, it seems like a PV system allows you to have an extra set of service-entrance conductors. I just don't get why they would "supply" power to a standby power system. I'm certain I'm misunderstanding this, but it seems like a standby power system would be supplying power, rather than have power supplied to it? Also, when it says an extra set is permitted, I'm imagining that extra set starting at the service point and going directly to the supply-side PV disconnect? I'm really new to the code...
 

SolarPro

Senior Member
Location
Austin, TX
I don't know if this helps clarify things or not, but as far as the Code is concerned most PV systems are "interconnected electric power production sources" (see Article 705) that are "operating in parallel with a primary source(s) of electricity," which is typically the utility.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
--How could service-entrance conductors supply power to a PV system, or any other standby power supply? Doesn't a standby power supply.... supply non-utility power?

First of all, if you are dealing with a grid-tie PV solar system, with no battery backup, then it isn't a standby power supply.

We typically talk about the the utility connection 'supplying' a grid-tie PV system, because the PV system will not operate without seeing utility voltage and frequency. We all know that the PV system will supply power in the other direction, but we still talk about the utility connection as a 'supply', and so does the code. For one thing, if there is a fault then the utility is more than capable of 'supplying' power to that fault.

As for actual standby power systems, whether they have a PV component or not, they may, for example, draw power from the utility to charge batteries that would be used if utility power is lost.

--How is this considered an exception? It sounds pretty close to the parameters of the original article.

All normal loads must be connected to one set of service entrance conductors. The exceptions refer to specific equipment that is not considered a normal load.
 
We typically talk about the the utility connection 'supplying' a grid-tie PV system, because the PV system will not operate without seeing utility voltage and frequency. We all know that the PV system will supply power in the other direction, but we still talk about the utility connection as a 'supply', and so does the code. For one thing, if there is a fault then the utility is more than capable of 'supplying' power to that fault.

Bingo. The exact answer I was looking for. This part of the question is cleared up for me. Thank you, jaggedben. I will gain full understanding if you can answer this:

I have little practical experience with service-entrance conductors. I am a PV systems designer who mainly works with load-side components, but I am trying to expand my knowledge of supply-side wiring as it relates to PV. As you said earlier, Article 240.30 states that all normal loads must be connected to one set of service-entrance conductors, and the exceptions relate to equipment that is not considered a normal load. If I had one set of service-entrance conductors supplying a normal service disconnect, could I also splice that same set so it supplies the PV disconnect? Or is that "one set" in Exception 5 considered an extra set, different than the one supplying the normal service disconnect? And if the splicing scenario is true, according to Article 230.71, I could splice the service-entrance conductors up to 6 times for individual service disconnects, and a 7th time for the PV disconnect?

Thank you.

Kind Regards,
Andy
 

Smart $

Esteemed Member
Location
Ohio
... If I had one set of service-entrance conductors supplying a normal service disconnect, could I also splice that same set so it supplies the PV disconnect? Or is that "one set" in Exception 5 considered an extra set, different than the one supplying the normal service disconnect? And if the splicing scenario is true, according to Article 230.71, I could splice the service-entrance conductors up to 6 times for individual service disconnects, and a 7th time for the PV disconnect?
Every set of conductors between service point and service disconnecting means or other disconnecting means or equipment permitted by exception is a service entrance conductor set... no matter how little or how much splicing is done. You can have one set of service entrance conductors to each permitted service disconnecting means and one to each permitted by exception disconnecting means or equuipment... or they can be combined, but no more than six disconnecting means are permitted for any one service entrance conductor set.
 

shortcircuit2

Senior Member
Location
South of Bawstin
Every set of conductors between service point and service disconnecting means or other disconnecting means or equipment permitted by exception is a service entrance conductor set... no matter how little or how much splicing is done. You can have one set of service entrance conductors to each permitted service disconnecting means and one to each permitted by exception disconnecting means or equuipment... or they can be combined, but no more than six disconnecting means are permitted for any one service entrance conductor set.

Should each additional set of service entrance conductors extend and connect at the service point to comply with the exceptions allowed in 230.40 then?
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Should each additional set of service entrance conductors extend and connect at the service point to comply with the exceptions allowed in 230.40 then?
Keep in mind that if POCO sets the service point as the main disconnect and there are multiple service OCPD/switches, then there is not a single service point.
Any point in the wiring system will still be on one side or the other of the service "point".
 
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