david
Senior Member
- Location
- Pennsylvania
.
In 2008 there was language about panels in series “In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all bussbars and conductors.”
Where in 705.12(D) 2014 does it address upstream towards the (service disconnect) utility supply.
I have looked very closely at the language in 2008 and 2014 codes.
Article 705 2008
(7) Inverter Output Connection. Unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it,
A connection in a panelboard shall be positioned at the opposite (load) end from the input feeder location or main circuit location.
The bus or conductor rating shall be sized for the loads connected in accordance with Article 220.
I am told to do a calculation add the sum of the amp rating of the overcurrent devices supplying the panel board.
After calculating the sum of the PV source Breaker(s) supplying the panels buss and the utility source breakers overcurrent protecting the panels buss, based on the result I’m told whether the breaker can be placed at any position on the buss or must be positioned at the opposite end of the buss.
Then for series rated panels it simply tells me to do the same thing with language making it clear that the value to use for the up stream panels is the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter.
In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductors.
So all this section is telling me for most applications in relation to the up stream panel breakers is move the breaker to the opposite end on the buss away from the main feeder or main over current device.
Article 690 2008
Bus or Conductor Rating. The sum of the ampere ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed 120 percent of the rating of the busbar or conductor
In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductor
In 2014 705.12 (D) other than the 120 % rule applied to the panel that the PV inverter output dedicated breaker(s) are connected to, only talks about calculations, whether it is for feeders or busses or conductorsare on the load side of the PV source connections point.
Is there anything in article 705 2014 NEC load side connections that requires, implies, or suggest that any of the calculations applied to the point of connection be applied up stream. From My reading of 705.12(D) the calculations are only required where both source currents the PV source and the Utility source currents can move in the same direction on conductors or busses.
It has been suggested that it is common sense to apply these corrections upstream. Is it to bold of a statement that the 2014 Code is moving away from concern over upstream buss ratings and feeder size source calculations? It seems to me it is more accurate that the 2014 code is only concerned where both currents move in the same direction at the same time. In other words on the load side of the PV source connection point
Article 690 2008
Bus or Conductor Rating. The sum of the ampere ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed 120 percent of the rating of the busbar or conductor. In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductors.
Article 705 2008
(7) Inverter Output Connection. Unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it, a connection in a panelboard shall be positioned at the opposite (load) end from the input feeder location or main circuit location. The bus or conductor rating shall be sized for the loads connected in accordance with Article 220. In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductors. A permanent warning label shall be applied to the distribution equipment with the following or equivalent wording:
In 2008 there was language about panels in series “In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all bussbars and conductors.”
Where in 705.12(D) 2014 does it address upstream towards the (service disconnect) utility supply.
I have looked very closely at the language in 2008 and 2014 codes.
Article 705 2008
(7) Inverter Output Connection. Unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it,
A connection in a panelboard shall be positioned at the opposite (load) end from the input feeder location or main circuit location.
The bus or conductor rating shall be sized for the loads connected in accordance with Article 220.
I am told to do a calculation add the sum of the amp rating of the overcurrent devices supplying the panel board.
After calculating the sum of the PV source Breaker(s) supplying the panels buss and the utility source breakers overcurrent protecting the panels buss, based on the result I’m told whether the breaker can be placed at any position on the buss or must be positioned at the opposite end of the buss.
Then for series rated panels it simply tells me to do the same thing with language making it clear that the value to use for the up stream panels is the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter.
In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductors.
So all this section is telling me for most applications in relation to the up stream panel breakers is move the breaker to the opposite end on the buss away from the main feeder or main over current device.
Article 690 2008
Bus or Conductor Rating. The sum of the ampere ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed 120 percent of the rating of the busbar or conductor
In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductor
In 2014 705.12 (D) other than the 120 % rule applied to the panel that the PV inverter output dedicated breaker(s) are connected to, only talks about calculations, whether it is for feeders or busses or conductorsare on the load side of the PV source connections point.
Is there anything in article 705 2014 NEC load side connections that requires, implies, or suggest that any of the calculations applied to the point of connection be applied up stream. From My reading of 705.12(D) the calculations are only required where both source currents the PV source and the Utility source currents can move in the same direction on conductors or busses.
It has been suggested that it is common sense to apply these corrections upstream. Is it to bold of a statement that the 2014 Code is moving away from concern over upstream buss ratings and feeder size source calculations? It seems to me it is more accurate that the 2014 code is only concerned where both currents move in the same direction at the same time. In other words on the load side of the PV source connection point
Article 690 2008
Bus or Conductor Rating. The sum of the ampere ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed 120 percent of the rating of the busbar or conductor. In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductors.
Article 705 2008
(7) Inverter Output Connection. Unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it, a connection in a panelboard shall be positioned at the opposite (load) end from the input feeder location or main circuit location. The bus or conductor rating shall be sized for the loads connected in accordance with Article 220. In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductors. A permanent warning label shall be applied to the distribution equipment with the following or equivalent wording: