Getting around 120% rule without line side tap

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nkb

Member
Location
NSL, UT
I have a 22kw system in Vegas. I need to get around the 120% rule but can't do a line side tap. Is there a panel I can upgrade to that would have an available service disconnect that I could use? Any other ideas?
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Yes, there are panels available that allow for multiple service disconnecting means.
In order to offer actual suggestions we'd need to know if this is 3-phase or single phase, and probably also the amperage rating of the service and output of the inverter(s).
 

nkb

Member
Location
NSL, UT
Yes, there are panels available that allow for multiple service disconnecting means.
In order to offer actual suggestions we'd need to know if this is 3-phase or single phase, and probably also the amperage rating of the service and output of the inverter(s).

It is a 3-phase system and the rating of the service is 200A. Inverter output is 43A, and there are two.
 

Smart $

Esteemed Member
Location
Ohio
I have to pit nick... :blink:

You said you can't do a line-side tap, but getting around the 120% rule using a multi-disconnect service panel is doing a "line-side tap"... which is self-contradictory.

So I have to ask why you said you can't do a line-side tap in the first place...???
 

nkb

Member
Location
NSL, UT
I have to pit nick... :blink:

You said you can't do a line-side tap, but getting around the 120% rule using a multi-disconnect service panel is doing a "line-side tap"... which is self-contradictory.

So I have to ask why you said you can't do a line-side tap in the first place...???

NV Energy will not allow a line-side tap in the "traditional" sense. A service disconnect breaker is ok.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
NV Energy will not allow a line-side tap in the "traditional" sense. A service disconnect breaker is ok.

I cringe when I hear this sort of thing. Does NV Energy legally own the conductors all the way to the service disconnect? Or do NEC rules not apply in Nevada? :slaphead: Where is the service point, and if it is anywhere ahead of the service disconnect then what legal right does the utility have to tell you that you can't do something on the customers side of it, if your local AHJ approves the installation?

Anyway, it sounds like your options, depending on the actual site details, are as follows:

1) Upgrade the service panel to one with space for multiple service disconnecting means. You could possibly cut this in ahead of the existing panel.
2) Upgrade it to a 250A or higher panel but keep the main breaker at 200A.

Ordinarily, without your comment above, I would add...

3) Install a new meter and tap box ahead of the existing one, perform your line-side-tap in the box, and jump the old meter with flats.

Whatever is least difficult and expensive, I guess.
 

nkb

Member
Location
NSL, UT
I cringe when I hear this sort of thing. Does NV Energy legally own the conductors all the way to the service disconnect? Or do NEC rules not apply in Nevada? :slaphead: Where is the service point, and if it is anywhere ahead of the service disconnect then what legal right does the utility have to tell you that you can't do something on the customers side of it, if your local AHJ approves the installation?

Anyway, it sounds like your options, depending on the actual site details, are as follows:

1) Upgrade the service panel to one with space for multiple service disconnecting means. You could possibly cut this in ahead of the existing panel.
2) Upgrade it to a 250A or higher panel but keep the main breaker at 200A.

Ordinarily, without your comment above, I would add...

3) Install a new meter and tap box ahead of the existing one, perform your line-side-tap in the box, and jump the old meter with flats.

Whatever is least difficult and expensive, I guess.

I was leaning toward the service panel with multiple service discos. Any recommendations on which panel is best?
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I was leaning toward the service panel with multiple service discos. Any recommendations on which panel is best?
Many AHJ's will not allow you to have more than one interconnect point in a service panel.
 

Smart $

Esteemed Member
Location
Ohio
Many AHJ's will not allow you to have more than one interconnect point in a service panel.
That's not mandated by the NEC, so to legally disallow multiple interconnects in a service panel, they would have to implement an amendment to Code.

The only other possibility is that POCO policies do not permit more than one interconnect. In that case, the AHJ cannot legally reject the application, but they can save the contractor/owner some headache by advising that the POCO will not connect if there is more than one.
 
I have a 22kw system in Vegas. I need to get around the 120% rule but can't do a line side tap. Is there a panel I can upgrade to that would have an available service disconnect that I could use? Any other ideas?

This is kind of goes along the same lines as a topic in the thread I started "PV only service" where you can get into a difference in semantics between a line side tap and two sets of service entrance conductors. IF they dont allow a "line side tap" do they allow another set of service entrance conductors feeding a separate but grouped service disconnect per 230.40 Ex 2 and 230.71? A line side tap is often the same exact thing - unless it isnt grouped with the "normal" service disconnect. Just hit a splice box or bussed gutter after the meter and run another set of service conductors to another service panel and tie in there. Throw a light and receptacle fed off that panel too so its not a "PV only" panel/line side tap ;)
 

mistermudd

Senior Member
Location
Washington State
So the new panel you select will have a bus rating of what?...and again where is the service point...you should find that out because IMO after the service point it is the AHJ per the NEC call and I doubt the utility goes all the way top of the service disco.
 

Smart $

Esteemed Member
Location
Ohio
So the new panel you select will have a bus rating of what?...and again where is the service point...you should find that out because IMO after the service point it is the AHJ per the NEC call and I doubt the utility goes all the way top of the service disco.
I agree it is AHJ and NEC (and any local amendments) after the service point... but POCO's have customer side "policies" that must be met before they will connect. As long as those policies are not a direct violation of the NEC, without consequence. They can opt to not connect the service, or disconnect an already energized service with little to no chance of any meaningful reprisal.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I agree it is AHJ and NEC (and any local amendments) after the service point... but POCO's have customer side "policies" that must be met before they will connect. As long as those policies are not a direct violation of the NEC, without consequence. They can opt to not connect the service, or disconnect an already energized service with little to no chance of any meaningful reprisal.
As in, they can refuse to pass inspection on a system that has more than one backfed CB in a panel.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
That's not mandated by the NEC, so to legally disallow multiple interconnects in a service panel, they would have to implement an amendment to Code.

The only other possibility is that POCO policies do not permit more than one interconnect. In that case, the AHJ cannot legally reject the application, but they can save the contractor/owner some headache by advising that the POCO will not connect if there is more than one.
It is in the 2014 code. And our utility does not allow line side taps either.
 

Smart $

Esteemed Member
Location
Ohio
It is in the 2014 code. And our utility does not allow line side taps either.
What is in the 2014 code???

Exactly what don't your utility allow??? If they allow GTI PV Systems, they have to be connected somehow, somewhere. IMO, the POCO cannot require a PV System to be load-side connected, as described in Article 705.12. What they do have a say in is where "service disconnects" (i.e. PV System disconnecting means for line-side connections) can be located... and that is it. Anything otherwise, it'd be a matter I'd take through the public utilities commission's complaint process.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
What is in the 2014 code???

Exactly what don't your utility allow??? If they allow GTI PV Systems, they have to be connected somehow, somewhere. IMO, the POCO cannot require a PV System to be load-side connected, as described in Article 705.12. What they do have a say in is where "service disconnects" (i.e. PV System disconnecting means for line-side connections) can be located... and that is it. Anything otherwise, it'd be a matter I'd take through the public utilities commission's complaint process.
705.12(D)(1)

Oh I don't need to go to the PUC because I don't care, but good luck getting anywhere with that any time soon.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
705.12(D)(1)

Oh I don't need to go to the PUC because I don't care, but good luck getting anywhere with that any time soon.

705.12(D)(1) does not prohibit multiple breakers in a service panel, as there is still no definition in the code pertaining to what constitutes "one system."
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
705.12(D)(1) does not prohibit multiple breakers in a service panel, as there is still no definition in the code pertaining to what constitutes "one system."

From an article in the IAEI magazine written by John Wiles who wrote the code, "This section has been revised to specifically require that multiple inverters in a single PV system shall be connected to the existing premises wiring system at a single dedicated circuit breaker or fusible disconnecting means. This section no longer allows multiple connections to a load center or panelboard where there are multiple inverters involved. Multiple inverters must first be combined in an AC combining panel and the output of the panelboard is then connected to the single point of connection in the distribution equipment through one circuit breaker or fusible disconnection means."
 

Smart $

Esteemed Member
Location
Ohio
From an article in the IAEI magazine written by John Wiles who wrote the code, "This section has been revised to specifically require that multiple inverters in a single PV system shall be connected to the existing premises wiring system at a single dedicated circuit breaker or fusible disconnecting means. This section no longer allows multiple connections to a load center or panelboard where there are multiple inverters involved. Multiple inverters must first be combined in an AC combining panel and the output of the panelboard is then connected to the single point of connection in the distribution equipment through one circuit breaker or fusible disconnection means."
As jaggedben points out, there are no provisions that define one PV System. What if I have one array/inverter on the house roof and another on a detached garage... is that one system or two?
(1) Dedicated Overcurrent and Disconnect. The source
interconnection of one or more inverters installed in one
system
shall be made at a dedicated circuit breaker or fusible
disconnecting means.
 

shortcircuit2

Senior Member
Location
South of Bawstin
How about we look at it from the perspective that the PV system is "one" source to be connected to the premises electrical supply provided by a Utility.

Then we go to the scope of article 705 as outlined in 705.1...705.1 Scope. This article covers installation of one or more sources operating in parallel with a primary source(s) of electricity.

Then we go to 705.12(D)(1) and it specifically says that... The source interconnection of one or more inverters installed in one system shall be made at a dedicated breaker or fusible disconnecting means.

I interpret that a PV system at a premises is one source and 705.12(D)(1) is telling me I shall connect the PV source at its interconnection point to a dedicated circuit breaker.
There are to many singular references for me to think otherwise.

So why would you need to connect it any other way? For what reason would you need multiple interconnections of one source?
 
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