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NEC 2020 Section 690.15 Question

copec

Solar Enthusiast
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I’m in the process of converting my illegal install to a legal. I have four strings wired straight to a junction box under a panel, I’m adding tigo modules for rapid shutdown, which seems to satisfy 690.13, but I’m confused by 690.15, do I need to add a physical disconnect or rapid shutdown switch within 10 feet of my panels to satisfy this?
 
Is your install:

'...mounted on rooftops of dwellings and other buildings'

Assuming you are mounted on roof (I think I remember that ground mounts do not apply or have different rules)...





"
Code Change Summary: A new code section now requires direct current combiner disconnects.

New requirements in 690.15(C) now specify that the DC output of DC combiners mounted on rooftops of dwellings and other buildings must have a load break rated disconnecting means either in the combiner box or within 6 ft. of the combiner.

This new rule allows first responders to quickly de-energize specific circuits in life safety emergencies or to make roof penetrations. Even though there are new rules on rapid shutdown in 690.12, there is no code language dictating where the rapid shutdown initiation device is to be located.

Having a load break disconnecting means within 6 ft. of a DC combiner located on the roof provides an additional measure of safety especially if the first responders cannot locate the rapid shutdown switch for the PV system conductors.

Below is a preview of the NEC. See the actual NEC text at NFPA.ORG for the complete code section. Once there, click on the “free access” tab and select the applicable year of NFPA 70 (National Electrical code).
"

and:

"
2014 Code Language:

690.15(C) Direct-Current Combiner Disconnects.
The dc output of dc combiners mounted on roofs of dwellings or other buildings shall have a load break disconnecting means located in the combiner or within 1.8 m (6 ft) of the combiner. The disconnecting means shall be permitted to be remotely controlled but shall be manually operable locally when control power is not available.
"



To me, that says in case the remote control becomes inoperable, it should also have a manual control method within 6ft of the combiner box.
 
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What if there isn’t a combiner box? I have all strings to a junction box that go straight through the attic to my inverter.
 
What if there isn’t a combiner box? I have all strings to a junction box that go straight through the attic to my inverter.

I would assume that the junction box could be interpreted as a DC combiner box...

Does your rapid shutdown system go open automatically if power is lost?

One thing you could do is to go down to the city or county (whoever will be doing the inspection), and ask them, since they would be the entity handling the inspection.
 
Per code, you can only parallel 2 strings without an inline fuse. If you have 4 strings, then all 4 strings should have an inline fuse. The fuse and inline fuse holder must be UL Listed and if exposed to the weather, listed for wet locations. Then you don't need a combiner box. You do need to make sure the wire you are connecting to that runs from your j-box to the disconnect switch is sized properly after applying temperature derating. Where the DC conduit enters the building it must be metal. Most of all, make sure everything is properly ground bonded.

I'll add a note of caution. Most solar fires are caused by loose DC connections. Connecting 4 strings to a home run requires every connection to be torqued and secured so wires can't pull out, and water can't easily bridge a gap between exposed metal parts. This happens even at the back of improperly made MC4 connectors of left in a place where water can pool. DO NOT use wire nuts in a j-box for HV DC please. That's why we use combiner boxes.

What inverter do you have?
 
Typing answers to all your responses while reading 690.15 again helped me figure it out I think. Thank you all for responding.

I believe the MC4 connectors on the junction box qualifies [690.15 (B) (1)] as a disconnecting means within 10' of the respective PV equipment, being the panels on the roof?

I'm adding Tigo TS4-A-O's to each panel, for which they document to comply with RSD by shutting down if they loose communication with the CCA head device. So I'm going to wire a UL e-stop switch in series with the CCA and also the inverter's power switch and also something with the battery system (when I add back in AGMs or UL9540 batteries). I am also putting in a lockable external lever disconnect switch that connects to the main load center.

I'll add a note of caution. Most solar fires are caused by loose DC connections. Connecting 4 strings to a home run requires every connection to be torqued and secured so wires can't pull out, and water can't easily bridge a gap between exposed metal parts. This happens even at the back of improperly made MC4 connectors of left in a place where water can pool. DO NOT use wire nuts in a j-box for HV DC please. That's why we use combiner boxes.

What inverter do you have?
I made the junction box, but I'm probably going to replace it with something UL anyways. For what it's worth I had used TEMco 10awg PV wire on the roof to the junction box for each string of 9 panels (old Trina TSM-265PC14 I picked up second hand about five years ago), and ran 10awg THHN wire from the four inverter inputs (two MPPT each combine two) through 1000VDC 10A MCBs, directly crimped into MC4s that are screwed down on the junction box itself, and I took great care in the crimping and the screwing. The MC4's still seal tightly to the outdoor PVC nema 3 box I used, with the gasket, and have plenty of thread and so are clamped down immovable on the box, but it is still outside of their listed UL use.

All conduit from roof entrance to garage is metallic and grounded (to main load center ground) as well as the racks and each panel. The inverter has ground-fault protection as well as arc-fault protection. The inverter is a Deye 8k-sg01lp1-us (I obtained some time ago before I knew anything about Sol-Ark because I noted the manufacturer of those those blue grid-tie inverters with limiters was Deye and so looked them up, and they had it on their website, so I bought one).
 
I came up with it on my own but my box is very similar to this box except it isn't combining, it just has the wire run from the garage (90C THHN 10 AWG) crimped directly in the MC4's. I was going to just swap out the MC4 for UL glands with like 6" of PV wire and make an actual junction in the box, but if I could find UL MC4 that are listed to screw down on the box I'll just do that for my projects from now on.

Does anyone happen to know of any UL MC4 connectors that have their listed use as being screwed down on a box? None of the ones I've come across do and it appears so many vendors sell boxes in which they do exactly that.
 
I came up with it on my own but my box is very similar to this box except it isn't combining, it just has the wire run from the garage (90C THHN 10 AWG) crimped directly in the MC4's. I was going to just swap out the MC4 for UL glands with like 6" of PV wire and make an actual junction in the box, but if I could find UL MC4 that are listed to screw down on the box I'll just do that for my projects from now on.

Does anyone happen to know of any UL MC4 connectors that have their listed use as being screwed down on a box? None of the ones I've come across do and it appears so many vendors sell boxes in which they do exactly that.
Not made by MC4, or Amphenol, no. UL requires that the mating connectors match. So, MC4 to MC4, or Amphenol to Amphenol, and not MC4 to Amphenol. I think the only ones you'll find are not made by either of them. You could use a cable gland and a WAGO splice. They're cheap and easy and UL listed.
 
Not made by MC4, or Amphenol, no. UL requires that the mating connectors match. So, MC4 to MC4, or Amphenol to Amphenol, and not MC4 to Amphenol. I think the only ones you'll find are not made by either of them. You could use a cable gland and a WAGO splice. They're cheap and easy and UL listed.
Thanks for the help!
 
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