Hawaiian Tie In

jaggedben

Senior Member
The wiring diagram in Post #11 would be a true supply side connection IF the breaker in the rightmost panel, which connects upstream of the main disconnect, were dedicated to PV only. If there are also loads downstream of that breaker is it not supply side.
It's probably a matter of semantics, but I disagree. The backfeed that is allowed at that connection is subject to the rules for supply side connections. For example if the service conductors were not rated for sum of the two service breakers, it would be non-compliant to backfeed more than their rating, even if all the load side aspects were compliant.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
It's probably a matter of semantics, but I disagree. The backfeed that is allowed at that connection is subject to the rules for supply side connections. For example if the service conductors were not rated for sum of the two service breakers, it would be non-compliant to backfeed more than their rating, even if all the load side aspects were compliant.
I may not be reading the schematic correctly, but it appears to me that there are loads as well as PV downstream of the isolated breaker at the right hand main. If that is the case, then the isolated breaker is just one of two main breakers and the PV connection is downstream of that main.
As I stated earlier, if there are no loads, only PV downstream of the isolated breaker, then it is a supply side connection.
A little more labeling on the schematic would help me.
 

jaggedben

Senior Member
I may not be reading the schematic correctly, but it appears to me that there are loads as well as PV downstream of the isolated breaker at the right hand main. If that is the case, then the isolated breaker is just one of two main breakers and the PV connection is downstream of that main.
As I stated earlier, if there are no loads, only PV downstream of the isolated breaker, then it is a supply side connection.
A little more labeling on the schematic would help me.
I don't think we're reading the diagram differently. It's how we're describing the rules. Again, in my opinion there are three connection points in series, and the breaker in the main is a supply side connection. It's also subject to Article 230 etc as a service disconnect, but the part of 705 that applies is the supply side section. I've had to argue this point in the past with AHJs who wanted to apply load side rules to MLO service panels. Generally 705 doesn't have that much additional to say about it that isn't covered in chapter 2, but the example I gave above is a possibility.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I see what you are saying, and I think that my view is based on the fact that with an MCB panel with a load side connection to the bus of that panel that bus connection is the PV interconnection point.
Using your categorization the connection between the one and only MCB and the service wiring could be called a supply side connection. In some sense it is, but I do not know of anyone who would categorize that PV installation as having a supply side connection.
 
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