Why

[jaggedben]

It's a bad diagram in as much as it doesn't make clear that the AC dsiconnect goes at the equipment. Neither disconnect in the photo is required by the NEC. Poco may have required one. But also, the one required at the equipment may have been fine for the poco.

 

[electrofelon]

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?

Ok, I didn't realize you had been there. Did you note what the placards say?

I agree it's probably a utility required disconnect that someone though had to be "dedicated" to that use.

There is a requirement to run DC through two poles sometimes to achieve the switch rating. Perhaps someone forgot that is for DC not AC. Only other WAG I can come with.

 

[Zee]

It's always good to assume there was a valid reason...for even the craziest stuff.
However, in this case, there may be no valid reason.

There are two requirements for AC disconnects:
1. an AC disconnect within line of sight from the inverter
2. If the solar is connected to the main supply side (AKA line side without a breaker), then an AC disconnect must be put near the main..... that must be minimum 60 amps and fusible.

So in the case of supply side connections it is a (60Afusible) switch switching a (30A) switch..... Which seems stupid electrically speaking.... but the point is to have an accessible switch near the inverter so no one is tempted to work on an inverter live ....but rather it's easy for them to reach and shut off power.

Of course these requirements can be met with a single disconnect if placed near the inverter and main at once.

I think the installer was new to solar and tried to follow the rules without understanding the intent.

THEN...... I think two mistakes were made.
First, the designers specified a fusible 60 amp but it's just one letter off for a Square D disconnect between that and a non-fusible disconnect, and I believe that's what was delivered.

The crew doesn't know and just installed what they got.

Second, mistake reading the single line diagram the two switches are right next to each other and either their locations weren't called out or the installation crew didn't realize that one switch should be near the inverter on the other one near the main
So they put them right next to each other kind of like the plans show.

Long story short there's no point here that I could see.
I have never seen anything like that or installed anything like it in 20 years.

Sent from my SM-S901U using Tapatalk

 

[Zee]

The use of PVC conduit gives me even less faith they knew what they were doing.
Unless it is a hurricane thing? Noticing the concrete stilts.

 

[roger]

The use of PVC conduit gives me even less faith they knew what they were doing.
Unless it is a hurricane thing? Noticing the concrete stilts.

PVC is normal for many installations in salt water environments, not just Hurricane prone areas.

 

[roger]

Noticing the concrete stilts.

They are probably 40 - 50' deep, the bottom of the structure is 16' above ground level, building code for the particular flood plane area.