ECN Forum Forums Code Related Discussion NEC & other Code issues Inverter Flirter

I was party to some recent speculation on having a 3 ph panel used in a residence, two phases per the usual incomming A&B, one phase per inverter provided 120Vac.

Note this would probably be a subpanel...

My first reaction was negative, two sources of power, balancing, etc.

Should I be in 690 for this?

I think a phase converter (Art.455) would be more suitable to this type of application. What do they want to run on 3 phase?

Don't know the particulars, Steve, but it sounds almost like the old "Delta Breaker" syndrome, again?
(2 sources on 1 C/B, kinda like the [prohibited] ones?)

[This message has been edited by electure (edited 02-08-2002).]

yes..'delta' came to mind... no, there is no 3 ph here, this would be considered an interactive system, some net metering is desired.

This will be a Trace system inverter tied into a normal 240/120v service entrance.

Normally the inverter's AC output would be a seperate panel. Usually as a photovoltaic array (or other inputs) grow, circuits are swapped from the main grid panel to the invereter panel.

What is speculated is having a meter/main 240/120v grid feeder run ser into a 3ph panel, two grid legs, one inverted leg.

Scott...et all.......
I've heard you Californian's are really making a biz of this......
check out the following ( i think we 'ammend' the first 3 chap's right??)

690.63 Unbalanced Interconnections.
(A) Single Phase. Single-phase inverters for photovoltaic systems and ac modules in interactive solar photovoltaic systems shall not be connected to 3-phase power systems unless the interconnected system is designed so that significant unbalanced voltages cannot result.
(B) Three Phase. Three-phase inverters and 3-phase ac modules in interactive systems shall have all phases automatically de-energized upon loss of, or unbalanced, voltage in one or more phases unless the interconnected system is designed so that significant unbalanced voltages will not result.
690.64 Point of Connection.
The output of a photovoltaic power source shall be connected as specified in 690.64(A) or (B).
(A) Supply Side. A photovoltaic power source shall be permitted to be connected to the supply side of the service disconnecting means as permitted in 230.82(5).
(B) Load Side. A photovoltaic power source shall be permitted to be connected to the load side of the service disconnecting means of the other source(s) at any distribution equipment on the premises, provided that all of the following conditions are met:
(1) Each source interconnection shall be made at a dedicated circuit breaker or fusible disconnecting means.
(2) The sum of the ampere ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed the rating of the busbar or conductor.
Exception: For a dwelling unit, the sum of the ampere ratings of the overcurrent devices shall not exceed 120 percent of the rating of the busbar or conductor.
(3) The interconnection point shall be on the line side of all ground-fault protection equipment.
Exception: Connection shall be permitted to be made to the load side of ground-fault protection, provided that there is ground-fault protection for equipment from all ground-fault current sources.
(4) Equipment containing overcurrent devices in circuits supplying power to a busbar or conductor shall be marked to indicate the presence of all sources.
Exception: Equipment with power supplied from a single point of connection.
(5) Equipment such as circuit breakers, if backfed, shall be identified for such operation

More 'permissive' fuel for the fire...

705.12 Point of Connection.
The outputs of electric power production systems shall be interconnected at the premises service disconnecting means.
(A) Integrated Electric System. The outputs shall be permitted to be interconnected at a point or points elsewhere on the premises where the system qualifies as an integrated electric system and incorporates protective equipment in accordance with all applicable sections of Article 685.




[This message has been edited by sparky (edited 02-13-2002).]

Sparky,
Gadzooks!
It seems very unorthodox to me, but every point you've cited says this is OK!
We aren't making anything out here from this sort of stuff. Everything is so regulated that you'd likely be in plan check/variances for 100 yrs. before you could get it through.
Anybody from around Taos, New Mexico??
(There's some real "out of the box" thinking and engineering there)

oohhh yeah..... !
They're an interesting bunch, very much in tune with ecological concerns, sort of a quest in thier trade.
I'm learning some fun terms like 'Gridnazi' & 'Gridmongers'
I think they wish to convert me from the 'dark side',being the only electrician in the class...LOL!
Anyhow, I'll try and contact some of the
Guru's that confiqure the systems
and post thier responses.


webmaster wrote sumpthin' bout old dogs, new tricks....re;CEE

[This message has been edited by sparky (edited 02-14-2002).]