Enphase long run ground wire size questions

[innavent]

This is a quick one. I have a 350' run with 16 x Enphase M215's. I plan on having a 20A AC switch (un-fused) at the array and then running underground and making my POC at a breaker in the main with a 20A breaker. I've run the Vdrop @ 2% max and need #6 wire. Do I need to up-size the ground wire also to #6? Which section (250 vs. 690) is correct for Enphase (up-sizing conductors is not required, or up-sizing is required to be equal to up-sized conductors)?

Thank you!!

 

[jaggedben]

You're talking about the AC equipment grounding conductor, so you follow 250 and you have to upsize if that's what 250 says. 690.45 is applicable only to DC circuits (photovoltaic source and output circuits). So it does not apply here.

 

[ggunn]

You're talking about the AC equipment grounding conductor, so you follow 250 and you have to upsize if that's what 250 says. 690.45 is applicable only to DC circuits (photovoltaic source and output circuits). So it does not apply here.

There's that pesky, often misunderstood "output circuits" term in the code again. You are, of course, correct; "output circuit" in this context refers to the DC output of a combiner box, not the AC output of an inverter as it is often misinterpreted to mean.

 

[rjhm]

It is pointless to mount a disconnect at the array with Enphase Micro Inverters. Whether the disconnect is open or closed, there is still AC Power going to it and in the conduit all the way to the AC means of disconnection at the main panel or sub panel powering the micro inverters.

 

[innavent]

It is pointless to mount a disconnect at the array with Enphase Micro Inverters. Whether the disconnect is open or closed, there is still AC Power going to it and in the conduit all the way to the AC means of disconnection at the main panel or sub panel powering the micro inverters.

I guess, unless you want to service the inverters or panels...

Thanks for the feedback, that's what I had thought!

 

[GoldDigger]

I guess, unless you want to service the inverters or panels...

Thanks for the feedback, that's what I had thought!

If you want to service the inverters, you just open the AC disconnect which is the backfeed breaker.
If you want to work on one microinverter but not disable the rest, unplug it from the AC wiring harness.
To service a panel, unlike with a string inverter, you just disconnect that panel from its microinverter, with or without disconnecting the AC side of the inverter. The only thing you need to take care with is that you shut down the inverter or cover the panel before disconnecting the PV at an MC connector. Those connectors are not designed to be unplugged under load.

 

[jaggedben]

To service a panel, unlike with a string inverter, you just disconnect that panel from its microinverter, with or without disconnecting the AC side of the inverter. The only thing you need to take care with is that you shut down the inverter or cover the panel before disconnecting the PV at an MC connector. Those connectors are not designed to be unplugged under load.

On an Enphase system, 'shutting down the inverter' is the same thing as disconnecting the AC side, whether that is done at the AC plug, a disco, or the breaker. And yes, having literally burned myself once (due to a miscommunication as to whether an inverter was turned on), I never disconnect panel connectors under load, even on microinverters.

With at 350' run to the breaker, yes, I would like to have a disconnect on the array. That's in case I forget my Enphase tool, or have to diagnose a short in the AC cable itself, or several other reasons. I will possibly save the expense of the disco in labor time during the install, and even more likely if I ever have to go out to service the system.

The question of whether to have an AC disco at the array is also irrelevant to the original question, since the wire has to be upsized for Vdrop regardless.

 

[Garrison]

The cost of a 2 pole, 240V, 30A disconnect is about $30. The cost of a quality junction box and handful of insulated tap connectors is around $60. On an array this far from the point of interconnection I would opt for the disconnect as long as you can maintain the working space requirements of 110.26, which can sometimes be a challenge with small ground mounts.

My 2?

 

[jaggedben]

The cost of a 2 pole, 240V, 30A disconnect is about $30. The cost of a quality junction box and handful of insulated tap connectors is around $60.

Wow, wish I could get a disco for that cheap. Anyway, you do not need fancy insulated tap connectors. You can use wire nuts (outdoor rated, if you're AHJ insists) or Buchanan splices. And you only need a standard outdoor bell box. It all comes to about $30 in my area. Your mileage may vary.

 

[tallgirl]

Wow, wish I could get a disco for that cheap. Anyway, you do not need fancy insulated tap connectors. You can use wire nuts (outdoor rated, if you're AHJ insists) or Buchanan splices. And you only need a standard outdoor bell box. It all comes to about $30 in my area. Your mileage may vary.

Still not a disconnect, and with a 700 foot round trip walking distance, well worth the money. The other thing I'd do with that disconnect is put a surge protector in it. Nice large piece of grounded metal, 350' from wherever, sounds like a magnet for a lightning strike or induced surge from a near miss.

 

[jaggedben]

Still not a disconnect, and with a 700 foot round trip walking distance, well worth the money.

Look above, my solution includes a disconnect.

The other thing I'd do with that disconnect is put a surge protector in it. Nice large piece of grounded metal, 350' from wherever, sounds like a magnet for a lightning strike or induced surge from a near miss.

Unfortunately with Enphase you can't really do this, because the Envoy won't work. There are some work-arounds, but still.

 

[Garrison]

Unfortunately with Enphase you can't really do this, because the Envoy won't work. There are some work-arounds, but still.

Are you suggesting that an Envoy will not work if a surge arrestor is installed in parallel on the inverter output circuit? All of our systems include surge arrestors, and all of our customers are able to monitor successfully through the Envoy.

Whose surge arrestors are causing communication issues for your systems?

 

[GoldDigger]

Are you suggesting that an Envoy will not work if a surge arrestor is installed in parallel on the inverter output circuit? All of our systems include surge arrestors, and all of our customers are able to monitor successfully through the Envoy.

Whose surge arrestors are causing communication issues for your systems?

I could see a problem if the surge protector included filter caps to ground or line to line un addition to the non-linear elements.
A line filter which includes series chokes could also be a problem.

 

[mwm1752]

If you want to service the inverters, you just open the AC disconnect which is the backfeed breaker.
If you want to work on one microinverter but not disable the rest, unplug it from the AC wiring harness.
To service a panel, unlike with a string inverter, you just disconnect that panel from its microinverter, with or without disconnecting the AC side of the inverter. The only thing you need to take care with is that you shut down the inverter or cover the panel before disconnecting the PV at an MC connector. Those connectors are not designed to be unplugged under load.[

Interesting

Certificate of Compliance
Certificate: 2395707
Master Contract: 240080
Project: 2657873
Date Issued: October 4, 2013
Issued to: Enphase Energy, Inc.
1420 N McDowell Blvd Petaluma, CA 94954-6515 USA

The products listed below are eligible to bear the CSA Mark shown with adjacent indicators 'C' and
'US' for Canada and US or with adjacent indicator 'US' for US only or without either indicator for
Canada only.
Sarah Ugolini
Issued by: Sarah Ugolini

PRODUCTS
CLASS 5311 09 - POWER SUPPLIES - Distributed Generation Power Systems Equipment
CLASS 5311 89 - POWER SUPPLIES - Distributed Generation - Power Systems Equipment
- Certified to U.S. Standards
Utility Interactive Micro Inverters, Models M215-60-2LL-S2x, M215-60-2LL-S2x-NA, M215-60-SIE- S2x,
M215-60-SIE-S2x-NA, M215-60-2LL-S2x-ZC, M215-60-2LL-S2x-ZC-NA, M215-60-2LL-S2x-IG,
M215-60-2LL-S2x-IG-NA, M215-60-2LL-S2x-IG-ZC, M215-60-2LL-S2x-IG-ZC-NA, M240-60-2LL- S2x,
M240-60-2LL-S2x-NA,M250-60-2LL-S2x, M250-60-2LL-S2x-NA, M250-60-2LL-S2x-ZC and
M250-60-2LL-S2x-ZC-NA.
For details related to rating, size, configuration, etc. reference should be made to the CSA
Certification Record, the Descriptive Report, or Attachment 1 - Ratings.
Notes:
- AC and DC connectors evaluated for disconnecting under load (for this application only).

 

[GoldDigger]

If you want to service the inverters, you just open the AC disconnect which is the backfeed breaker.
If you want to work on one microinverter but not disable the rest, unplug it from the AC wiring harness.
To service a panel, unlike with a string inverter, you just disconnect that panel from its microinverter, with or without disconnecting the AC side of the inverter. The only thing you need to take care with is that you shut down the inverter or cover the panel before disconnecting the PV at an MC connector. Those connectors are not designed to be unplugged under load.[

Interesting

Certificate of Compliance
Certificate: 2395707
Master Contract: 240080
Project: 2657873
Date Issued: October 4, 2013
Issued to: Enphase Energy, Inc.
1420 N McDowell Blvd Petaluma, CA 94954-6515 USA

The products listed below are eligible to bear the CSA Mark shown with adjacent indicators 'C' and
'US' for Canada and US or with adjacent indicator 'US' for US only or without either indicator for
Canada only.
Sarah Ugolini
Issued by: Sarah Ugolini

PRODUCTS
CLASS 5311 09 - POWER SUPPLIES - Distributed Generation Power Systems Equipment
CLASS 5311 89 - POWER SUPPLIES - Distributed Generation - Power Systems Equipment
- Certified to U.S. Standards
Utility Interactive Micro Inverters, Models M215-60-2LL-S2x, M215-60-2LL-S2x-NA, M215-60-SIE- S2x,
M215-60-SIE-S2x-NA, M215-60-2LL-S2x-ZC, M215-60-2LL-S2x-ZC-NA, M215-60-2LL-S2x-IG,
M215-60-2LL-S2x-IG-NA, M215-60-2LL-S2x-IG-ZC, M215-60-2LL-S2x-IG-ZC-NA, M240-60-2LL- S2x,
M240-60-2LL-S2x-NA,M250-60-2LL-S2x, M250-60-2LL-S2x-NA, M250-60-2LL-S2x-ZC and
M250-60-2LL-S2x-ZC-NA.
For details related to rating, size, configuration, etc. reference should be made to the CSA
Certification Record, the Descriptive Report, or Attachment 1 - Ratings.
Notes:
- AC and DC connectors evaluated for disconnecting under load (for this application only).

OK. I would expect that either :
1. These are not standard MC connectors on the inverter side or
2. They have done their own tests for the specific condition of single panel instead if string voltage and known non-inductive load.

 

[jaggedben]

Are you suggesting that an Envoy will not work if a surge arrestor is installed in parallel on the inverter output circuit? All of our systems include surge arrestors, and all of our customers are able to monitor successfully through the Envoy.

Whose surge arrestors are causing communication issues for your systems?

A parallel surge arrestor shouldn't be a problem. A series surge protector would be.