Splicing in a meter bank

[david]

Not sure why you thought that, but the inverters really can't deliver fault current above their normal operating current. So they are basically a rounding error compared to the available fault current from the utility. With very large systems this might not be the case but even with 60kW all put together from the multiple units that's pretty much going to be the case here.

Actually I'm getting that Idea from Mike Holts Video

2014 NEC- Point of Conection To Utility Power [705.12] (1hr:28min:43sec)

I'm pretty sure he saying the buss rating must be sized to handle fault current from both sources additive

 

[iwire]

But there is almost zero fault currents, the inverter simply cannot output much more than its rating. It is not like a transformer. It is solid stare and simply cannot produce high currents.

 

[Carultch]

But there is almost zero fault currents, the inverter simply cannot output much more than its rating. It is not like a transformer. It is solid stare and simply cannot produce high currents.

I guess what they mean is that you still have to verify that it isn't the straw that broke the camel's back.

 

[david]

But there is almost zero fault currents, the inverter simply cannot output much more than its rating. It is not like a transformer. It is solid stare and simply cannot produce high currents.

I don’t think they are saying the solar is producing high currents, I think they are saying all currents will move in a direction towards the fault point until the utility high currents open the fault path.

If a fault happens in the MDP like the one I saw at a Hills Department Store where a worker dropped a wrench in the buss section and shorted out the buss. Whatever the reason for the fault,

If the fault is on a path that both currents would move in the same direction on. The buss has to be oversized by using the 120% rule.
That is exactly what we have with the center feed MDP in this discussion. If we have a fault in the MDP current from both sources will travel toward the fault until the current path from the utility is opened .

I am open to consider the buss rating calculation not necessary., But I would first like to hear your opinion on the PV current adding to the high magnitude utility current in a fault condition

 

[jaggedben]

In practice, most situations in residential PV installations will look something like this: The available fault current from the utility is 10,000A and the available fault current from the inverter is 40A. In such cases the inverter should really have no bearing on the equipment selected.

In large commercial or utility scale systems the situation could be different, and the PV fault current more than a rounding error.

 

[mivey]

But there is almost zero fault currents, the inverter simply cannot output much more than its rating. It is not like a transformer. It is solid stare and simply cannot produce high currents.

I would not say 0X but rather 1X for each inverter stacked into this cluster rather than the small 1.2X we might see with some sources to upwards of 50X-70X from the supply side.