Why

[roger]

Before I retired I was involved in a few PV installations and admit I'm not well versed in these installations but, what would be the reason for having a 60 amp non fusible switch above a 30 amp non fusible switch.

 

[Little Bill]

Before I retired I was involved in a few PV installations and admit I'm not well versed in these installations but, what would be the reason for having a 60 amp non fusible switch above a 30 amp non fusible switch.
View attachment 2569012

Maybe they needed a 90A disconnect

 

[Krusscher]

I would guess there are conductors that go through the top disconnect and terminate in the bottom one.

 

[ggunn]

I would guess there are conductors that go through the top disconnect and terminate in the bottom one.

I just noticed that the two bottom switches each have one conduit going in the top and two coming out the bottom, all of which go to the right. It looks like they run to one of the enclosures on the opposite side of the column from what I assume is the main, but what those boxes are are anyone's guess.

It looks like an electrician's fever dream.

 

[wwhitney]

I just noticed that the two bottom switches each have one conduit going in the top and two coming out the bottom.

Zooming in on the photo, I don't believe that's correct; I believe each bottom switch just has one conduit exiting the bottom. The shadows and color of the concrete pillar are a bit deceptive.

I favor the speculation in post #3 that each of those conduits carries two circuits, and so you have two stacked disconnects.

Cheers, Wayne

 

[jaggedben]

There's been a fair amout of needless utility requirements for knife-blade disconnects over the years. Perhaps that was a contributing factor here.

 

[roger]

I would guess there are conductors that go through the top disconnect and terminate in the bottom one.

The top is connected line load, the bottom is the same. IOW's, a switch switching a switch.

 

[roger]

Zooming in on the photo, I don't believe that's correct; I believe each bottom switch just has one conduit exiting the bottom. The shadows and color of the concrete pillar are a bit deceptive.

I favor the speculation in post #3 that each of those conduits carries two circuits, and so you have two stacked disconnects.

Cheers, Wayne

You are correct, there is one conduit with one set of wires entering the top switch which is switching a set of conductors entering the top of the lower switch which is switching a set of conductors exiting the bottom of the lower switch. There is only one circuit in each set up that routes through both top and bottom switches, a switch switching a switch.

 

[Little Bill]

Can you switch the switches that are switching the switch?

 

[roger]

Can you switch the switches that are switching the switch?

I don't think so since one is a 60 and one is a 30.

 

[Fred B]

Could you actually be getting one set just feeding through from the top one that switches the other set with second set switched on bottom one? Rather than a switch switching a switch.
Could you have actually 4 banks of PV, 2 larger banks under 60A and 2 smaller banks under 30A?

 

[roger]

Could you actually be getting one set just feeding through from the top one that switches the other set with second set switched on bottom one? Rather than a switch switching a switch.
Could you have actually 4 banks of PV, 2 larger banks under 60A and 2 smaller banks under 30A?

There are actually two independent systems (modules, inverters, batteries, etc...) so for this conversation we need to ignore one set. We have one set of conductors consisting of a black and red #8. The two switches are in series from the inverter to the panel.

 

[GoldDigger]

All 4 switches have some sort of placard labeling, different between the upper and lower, and a red placard (alternate power source?) above the whole thing. Depending on what is in the two panels on either side, I question whether we have a practical 6 throw service disconnect situation.
Possibly one switch in each pair is a direct open contact disconnect while the other switch acts on a signal/control wire back to a rapid shutdown system?

 

[jaggedben]

I quite doubt it. They all look like ordinary Square-D safety switches.

 

[electrofelon]

You are correct, there is one conduit with one set of wires entering the top switch which is switching a set of conductors entering the top of the lower switch which is switching a set of conductors exiting the bottom of the lower switch. There is only one circuit in each set up that routes through both top and bottom switches, a switch switching a switch.

Are you speculating or did you see inside the switches?

 

[roger]

Are you speculating or did you see inside the switches?

I have been in the switches. The owner is replacing the whole set up because it was all submerged in the last Hurricane. I am helping him put a list together. The question is simply, is there any reason for two switches to be in series in any PV installation?

 

[Fred B]

Could it be an attempt at this from image in handbook? This if condensed in size related to your installation it might end up looking like your install.

 

[roger]

I think you may be on to something Fred, that's pretty much what he has, thanks.

 

[Fred B]

It would seem rather redundant given the proximity of the A/C disconnect and Utility disconnect in your application.

Might have been a POCO required situation.

 

[roger]

It would seem rather redundant given the proximity of the A/C disconnect and Utility disconnect

It certainly is.