The notes in the NEC 2020 Handbook for article 706 clearly state that
706 only covers ESS which is an assembly of components, and that the
total assembly must be listed under UL 9540.
Further it states: "/A group of separate components that includes
storage batteries, that is provided with support systems (racks), charge
controllers, and inverters, and that does NOT have an overall listing as
an ESS is a storage battery system and as such is subject to the
requirements of article 480"/
and just in case someone says the notes don't matter, 706.5 says:
"/Energy Storage systems shall be listed"/.
So, since I have never used an actual listed ESS, I'm back to 480.
Specifically, 480.7 (A) says we need a disconnect for batteries over 60
vdc (48v should be exempt) and then 480.7(B) says houses need to have an
outside disconnect for the batteries labeled "Emergency Disconnect".
So here's the real question: Does 480.7(A) exempt us from 480.7(B)?
Ray Walters
Remote Solar
303 505-8760
On 3/9/19 8:08 PM, Brian Mehalic wrote:
Hi Glenn, I don't completely agree with your interpretation of ESS
systems and the application of Article 706. Yes, an ESS /could/
provide 120/240 VAC (e.g. the Powerwall), but the figures in Article
690 show three different configurations where the output of the ESS is
not AC, and where the ESS disconnect comes before any power
electronics (like a multimode inverter, as shown in the AC and DC
coupled systems) or loads (as shown in the stand-alone system). Are
those ESS connected to other systems which utilize stored energy to
provide AC power? Yes, but the key is "connected to other systems" -
in many cases the ESS only provides DC. In fact the definition of ESS
clearly states this - it /can/ have AC or DC output, and it /may/
include power electronics (but may not).
My understanding is that the 60 volt limit (which is obviously
problematic in a world where 48 VDC batteries and ESS are very common)
was inserted in order to exempt other devices that store energy (such
as UPS, or battery backup in fire alarms/exit signage/etc.) from the
706 requirements.
Cheers,
Brian Mehalic
NABCEP Certified Solar PV Installation Professional™ R031508-59
National Electrical Code® CMP-4 Member
(520) 204-6639
Solar Energy International
http://www.solarenergy.org
SEI Professional Services
http://www.seisolarpros.com <http://www.seisolarpros.com>
On Sat, Mar 9, 2019 at 4:07 PM Glenn Burt <[email protected]
<mailto:[email protected]>> wrote:
Hi Ray,
This is a conversation I have had some time ago with a number of
my fellow inspectors and code experts. When the 2017 NEC came out,
I agreed with Mike Holt and Bill Brooks' assessment that the new
article was poorly written and did not apply to most systems being
installed today. After much discussion through my Cadmus network
of authorities, it emerged that indeed 706 apples to the typical
residential systems.
So Energy Storage Systems (ESS) are the point of article 706, and
I believe that the key point is that the SYSTEM is generating AC
voltage of 120VAC or 240VAC, making the system fall under article 706.
Batteries themselves are minimally covered by NEC 480, NFPA 1, and
the IFC as applicable locally.
So, the bottom line is that the new article does cover the work we
do when systems provide or interface with 120VAC or above (making
the system operation exceeding the 60V AC trigger).
My initial problem was believing that the article applied to a
component (the battery bank), and not the system (all components
taken together as a generator/storage system). It is an easy
misunderstanding to make.
Hope this helps!
-Glenn Burt
-----Original Message-----
From: RE-wrenches <[email protected]
<mailto:[email protected]>> On Behalf Of Ray
Sent: Saturday, March 09, 2019 12:41 PM
To: RE-wrenches <[email protected]
<mailto:[email protected]>>
Cc: Bill Brooks <[email protected]
<mailto:[email protected]>>; Bill Brooks <[email protected]
<mailto:[email protected]>>
Subject: [RE-wrenches] NEC for Batteries < 60v ??
Hi Everyone;
I'm updating all my verbage on plansets, and I just realized that
the newly created article 706 covering Energy Storage Systems is
only for Over 60 VDC (706.1) Also article 480 for batteries only
requires disconnecting means over 60 VDC ?! (480.7). I'm not
about to not have a disconnect, so now that NEC pulled battery
systems out of 690, where do we go for guidance on normal battery
systems: 12, 24, 48 VDC?
Overall, I welcome most of the changes in NEC 2017, like
separating off grid systems into articles 706, and 710, but it
seems us off grid installers need some more clarification.
Thanks,
--
Ray Walters
Remote Solar
303 505-8760
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