Rapid shut down

[jaggedben]

1. OK it seems SMA RSS complies with NEC 2014, and only maybe with NEC 2017.
Anyone disagree that the SMA RSS complies with NEC 2014?

2. There is the Device (at array) and the Controller (near MSP or Inverter).
Some control circuit must be run to connect the two.
Is it Code Compliant to run the control wiring (low voltage wire) from the Device at array to the Controller along with DC circuit conductors in EMT down off roof?
I figure that would save major time of running separate conduit and/or ugliness of stapling cable to wall.

3. I seem so intrigued by this Rapid Shutdown discussion all of a sudden .....not sure why....maybe b/c I just got my first building permit plan-set rejected for lack of RSS:weeping::weeping:. Ahhh 2017.

I am employing an SMA 5.0 Inverter, so I plan to use the above SMA solution. Reasons: same make, works with SPS. We are on NEC 2014.

Probably not compliant to run the control wire with the PV circuits. Maybe if the instructions say you can, and the whole system is listed to UL 1741, you could make an argument. Seems like a stretch.

Secondary question is whether the control wire needs to be in a raceway.

 

[Zee]

Thanks for that, jaggedben.

Here is what I found in the SMA installation manual:

6.4 Connecting the Rapid Shutdown Box and Rapid
Shutdown Controller Together
......
☐ Conduit: either a separate conduit (trade size: 16 mm (0.5 in) or smaller with suitable reducer
bush) or use the conduit of the output strings to lay the conductors.
☐ If the conductors for the connection of the Rapid Shutdown Controller are to be laid in a
separate conduit: raintight or liquidtight conduit fitting (trade size: 16 mm (0.5 in) or smaller
with suitable reducer bush).
☐ When laying a tray cable for exposed run (TC-ER): use cable gland which is suitable for the
cable and the enclosure opening.
.....
☐ Number of conductors: 5
☐ If the conductors for the connection of the Rapid Shutdown Controller are laid in one conduit
together with the output strings, the conductors for the connection of the Rapid Shutdown
Controller must be insulated for the maximum PV system voltage.

☐ ......(18 AWG to 16 AWG)
........
Complying with the requirements for class 2 circuits
The circuit of the Rapid Shutdown Controller meets all requirements for class 2 circuits. The
maximum open-circuit voltage is 20 V and maximum short-circuit current is 400 mA.
☐ All electrical installations must be carried out in accordance with the locally applicable
electrical standards and the National Electrical Code

Looks like I am good to run control circuit with DC output hot wires? (It is UL 1741 listed and certified)

 

[shortcircuit2]

725.136 prohibits running class 2 circuits in the same raceway.

 

[GoldDigger]

725.136 prohibits running class 2 circuits in the same raceway.

Unless they are re-identified as Class 1 and run using Chapter 3 wiring methods.
The information that you technically need to get from the manufacturer is whether the run can in fact be re-identified as Class 1 without causing any problems on the non-powered end.

 

[jaggedben]

725.136 prohibits running class 2 circuits in the same raceway.

Unless they are re-identified as Class 1 and run using Chapter 3 wiring methods.
The information that you technically need to get from the manufacturer is whether the run can in fact be re-identified as Class 1 without causing any problems on the non-powered end.

This stuff is irrelevant unless you've already decided that running them together doesn't violate 690.31(B). (690.4(B) prior to the 2014 cycle.) I suppose the fact that the manufacturer talks about running them together is a point in favor of being able to do so. I suppose another point in favor is that these circuit conductors are powered by the PV source? I'm sure we can continue to have an interesting discussion about this.

 

[Zee]

Thanks to all.
I decided to run (5) #14 AWG conductors for the control circuit, and pulled them in the same conduit as the dc output.
Otherwise, I could have only gotten 300 V rated and solid wire if I wanted #16 or #18 size.
I needed 600V and stranded. (my dc output circuits are about 350vdc max in cold)
I was able to get #14, 600 V rated, THHN to match the V rating of the DC output circuit conductors (600V).

If SMA says it is OK in one conduit, I am OK.

Frankly i do not know class 2 or class 1:dunce::ashamed1:

But looking ahead........Given Rapid Shutdown Requirements...i dunno if I am gonna install SMA any more.:blink:
Cost me over $400 in parts, that much in labor too, and more materials and planning.

Major win for SolarEdge and Enphase.

 

[Zee]

The latest SolarEdge RSS does away with the need to open the DC disconnect. Now it operates on loss of utility AC.

I cannot find any documentation on HOW to INITIATE the rapid shutdown. All the videos and docs I have seen pertain to their field-installed upgrade kit pre-2017. They always refer to the "safety switch" or AC/DC switch.

Do you have a source for that?

 

[jaggedben]

Look on the datasheets, about two thirds of the way down there is a line that at least on some datasheets specifies whether it is the DC switch or whether AC side shutoff automatically initiates. It depends on the model. HD Wave and higher power 3-phase models intiate on AC shutoff.

 

[Zee]

Look on the datasheets, about two thirds of the way down there is a line that at least on some datasheets specifies whether it is the DC switch or whether AC side shutoff automatically initiates. It depends on the model. HD Wave and higher power 3-phase models intiate on AC shutoff.

Thanks.

Nothing.
Not on website, not in manual, not on datasheet.
Datasheet, under rapid shutdown it says: "Yes". :dunce:

How to initiate is key.

 

[shortcircuit2]

Good point Zee. I don't see anything in SE paperwork on how to actually initiate the RS function. I been told by SE that you need to shutoff the DC switch on the inverter to have the system go to safe voltage. This is on the SE inverters...and I've done many field tests to see this happen.

This is the kit we added to the inverters to make them RS compliant...

http://www.solaredge.com/sites/defa..._single_phase_inverter_installation_guide.pdf

Then, the HD-Wave inverters come ready to comply with safe voltage by killing the AC input. I have field tested a few of these.

But I don't have any instructions on paper on the procedure. Maybe no paperwork yet because it is not listed as such.

Is this what you are looking for? Instructions on RS?

 

[SolarPro]

Thanks.

Nothing.
Not on website, not in manual, not on datasheet.
Datasheet, under rapid shutdown it says: "Yes". :dunce:

How to initiate is key.

Last I checked, the single-phase SE inverters still use dc initiation. (There is no longer any need to retrofit parts into the dc disco.) The high power 3-phase units are now shipping with "automatic" (meaning loss of ac power) RS initiation.

[Fremont, CA] SolarEdge is facilitating compliance with NEC 2014 and NEC 2017 rapid-shutdown requirements by integrating automatic rapid shutdown into its highest-power commercial inverters. Automatic rapid shutdown is designed to activate when the ac supply to the inverters is no longer present. For larger installations with string inverters located in various locations on a commercial rooftop, this helps first responders know that with one action, they can reduce the entire commercial array to a safe low-voltage state. SolarEdge is currently shipping its 3-phase 277/480 Vac SE33.3K-USR inverters and 3-phase 208 Vac SE14.4K-USR inverters with integrated automatic rapid shutdown. These inverters do not replace the standard SE14.4K-US and SE33.3K-US models that allow installation with or without a kit for manual rapid shutdown

SolarEdge / 510.498.3200 / solaredge.com

 

[jaggedben]

I agree the documentation on the optimizers shutting down voltage when the DC switch is thrown is terrible. They need to re-publish something on that.

The datasheets do say "Automatic Rapid Shutdown upon AC Grid Disconnect" for the HD Wave and the relevant 3-phase inverters. If it doesn't say that for the inverter you're using then you need to use the DC switch.

Note that for 2017 compliance if you happen to have the inverter on the outside of the building (readily accessible) and the service disconnect on the inside, the DC switch still complies with the requirement.

 

[Zee]

Thank you, Gentlemen.

That is a surprise !
And here I was assuming SE inverters now all had rapid shutdown initiated by loss of AC power...I thought it was just a matter of missing documentation to that effect.

I am going to contact them to be sure.

(I do want to label my systems in compliance with NEC 2014 req's....and that includes the requirement to describe how to initiate rapid shutdown.

I already have a label I print for all Enphase systems:
"OPEN SERVICE DISCONNECT
TO INITIATE RAPID SHUTDOWN")

 

[Zee]

Geez, if this is true this means:
1.on residential installs an SE inverter will have to be outside and readily accessible.
2. SMA has a difficult workaround
....so, this is gonna be EVEN BETTER for Enphase. These rapid shutdown req's are so much work, that I'll just do micros.

 

[jaggedben]

You can put another DC disconnect outside if that's easier than moving the inverter.

 

[Zee]

You can put another DC disconnect outside if that's easier than moving the inverter.

According to tech support, if the AC/DC switch initiates rapid shutdown, then only the actual AC/DC switch on inverter initiates rapid shutdown. An external DC Disco won't do it. The resistors need to be activated.
(Neither will loss of AC power, of course)

 

[310 BLAZE IT]

NOTE: P700 may not be Rapid shutdown 2019 compliant with some modules. 80v is exceeded by 2 modules in series. Ex. Trina 340w: [FONT=&quot]46.5 Voc x2 = 93V[/FONT]

 

[shortcircuit2]

According to tech support, if the AC/DC switch initiates rapid shutdown, then only the actual AC/DC switch on inverter initiates rapid shutdown. An external DC Disco won't do it. The resistors need to be activated.
(Neither will loss of AC power, of course)

Note that it is only an DC switch...a AC switch needs to be located near the inverter.

The HD-WAVE works on AC shutdown...