Disconnect switch orientation

[Grouch1980]

Hi all,
In any setup where you have disconnect switches feeding solar PV arrays, for example, say you have a service disconnect switch feeding a step-up transformer, which in turn feeds a secondary disconnect switch, which in turn feeds an AC combiner panel that feeds the solar inverters. Do the fuses and switches inside the SDS and secondary disconnect switch have to be flipped? Since power flows from the PV arrays to the service, do the switch mechanisms inside the disconnects now have to be on the line side (the side with the PV arrays), and the fuses on the load side (the side with the utility)?

 

[jaggedben]

No. For a grid-tied system, the side that energizes the equipment (and has the higher fault current) is still the utility, so the utility side should still be treated as line. If you have to replace fuses you want them de-energized and it's no different than with a load.

With stand alone systems or systems with battery backup and other sources there could be a slightly different situation, but probably not as much as you'd think.

 

[ggunn]

Think common sense. If the utility were connected to the load side of a fused disconnect the fuses would still be hot when the switch is turned off; would you want to service that disco? The utility is always on the line side of a disco no matter which way the current is flowing.

 

[Grouch1980]

would you want to service that disco?

 

[Grouch1980]

Thank you both!