Salt Lake City Residential ENERGY STORAGE SYSTEM (ESS)
Plan Review Checklist
For ESS systems also utilizing a string inverter or micro inverter solar PV system, please also see the appropriate City plan review checklist requirements for such solar PV system. Such solar PV requirements will apply in addition to those found in this checklist.
This review is not all inclusive and all system components and equipment must be installed per adopted code, city ordinances, and manufacturer requirements regardless of whether or not such items or issues have been addressed using this checklist.
General
- ____Provide two complete sets of construction drawings, line diagram(s), and site plan.
- ____Provide two complete sets of manufacturer specs and system component information.
Manufacturer specifications are required (where applicable per the system design) for the
following items: inverter(s), solar modules (panels), any DC combiner panels, any DC to DC
converters/power optimizers, disconnect switches, any new AC panelboards, batteries, charge
controllers, and the supporting racking system. For ESS systems utilizing a string inverter or micro inverter solar PV system, please also see the appropriate City plan review checklist requirements for such solar PV system. Such solar PV requirements will apply in addition to those found in this checklist.
Site Plan
- ____Site plan must show the location of the home’s service panelboard, any sub-panelboard (that
is to be back-fed by the system), location of the backed-up loads panel (critical loads panel),
location(s) of the inverter(s), location of batteries, locations of charge controllers, locations of any
disconnects, and locations of any other equipment associated with the system. - ____Show any detached structure on the property (if equipment is to be installed inside or outside
of such structure) and show dimensions from such structure to property lines. - ____Show on the site plan the location of the main disconnect that will shut down the energy
storage system (ESS). For one-family and two-family dwellings, there must be a disconnecting
means or its remote control located at a readily accessible location on the outside of the home or
building. See NEC 706.15(A). - ____If required per the AHJ due to a large number of individual devices installed for a system,
please provide a floorplan layout of the room(s) in the home or building that will contain battery
backup system (and any other equipment associated with the system). Please show the locations
of all equipment on such floorplan and show clear working spaces in front of all equipment. NEC
706.20(C) and 110.26. The batteries cannot be installed in the clear working space of any other
electrical equipment. Note: many jurisdictions may choose to not require a floorplan layout when
all equipment will be outside or in a garage. - ____If there will be new underground conduit installed for the system, please show on the site
plan the location where such conduit will be installed and also specify the burial depth of such
conduit, in accordance with NEC 300.5.
Line Diagram
- ____Show all system components and electrical equipment on the diagram, such as: J-boxes,
combiner box (if used), inverter(s), panelboards, disconnects, batteries (or other energy storage
component) and other equipment like charge controllers (if used). Indicate where all the
components will be located in or on the home. - ____Show any electrical panelboards that will be backed up by the ESS system (a backed-up
loads panel is also often called a critical load panel – which is for the loads that will receive
power from the battery system when the utility source of power (or other primary source of
power) is not available for the home). - ____Specify on the diagram the ampacity rating of all panelboards and the ampacity rating of any
breakers that feed such panelboards. - Show on the line diagram a disconnect that will shut down the energy storage system (ESS).
For one-family and two-family dwellings, there must be a disconnecting means or its remote
control located at a readily accessible location on the outside of the home or building. See NEC
706.15(A). - ____Please specify on the line diagram if equipment, panelboards, and wiring will be new or
existing. - ____Show all wire sizes, and wire types to be provided for each section of wiring between
electrical equipment. NEC Articles 240 and 310. - ____Wire sizing for circuits connected to the ESS system must be sized per the ESS
manufacturer’s instructions and NEC 706.30. - ____Please show on the plans that all circuits (AC and DC) connected to the ESS will be
protected from overcurrent. NEC 706.31(A). See installation instructions for the ESS concerning
requirements for overcurrent protection. - ____Per NEC 706.31(F), when overcurrent protection is required for a circuit connected to an
energy storage component (such as batteries), and such circuit passes through a wall, floor, or
ceiling, the required overcurrent protection must be provided at the energy storage component
end of the circuit. For example, if a battery enclosure (not having built-in overcurrent protection)
is installed on the other side of a wall from the battery inverter, there must be provided an
overcurrent device for the battery circuit and the overcurrent device needs to be next to the
battery enclosure. See installation instructions for the ESS concerning requirements for
overcurrent protection. - ____Specify on the diagram the ratings of all breakers or fuses (DC and AC overcurrent
protection devices). NEC 706.31(B) and 240.4. Please also show on the diagram the ampacity
ratings of any breakers that are included as part of listed ESS equipment. - ____Unless wiring will be factory installed as part of listed equipment, please specify on the
diagram the size and type of conductors (wires) that interconnect batteries and extend to the
inverter. Such wires must be sized in accordance with the ampacity rating of the battery system
DC fuses or DC breaker as specified by per the inverter manufacturer. See NEC 706.31 and
110.3(B). - ____If fine-stranded cables are going to be installed, specify on the plans that only terminals, lugs,
devices, and connectors that are listed and marked for such use can be installed for such wires.
NEC 110.14. All fittings for fine stranded cables must also meet UL 486 A&B. - ____Specify the size and type of all equipment grounding conductors for each section of wiring
on the diagram. NEC Article 250, Parts VI and VII. - ____Specify the size and type of any required grounding electrode conductors for the system.
NEC Article 250, Part III. - ____Show on the diagram all conduit types, sizes, and how many conductors will be in each
conduit for each section of wiring between electrical equipment. NEC Chapter 3. - ____Specify locations where conduit and/or cables are to be installed.
- ____Indicate on the diagram what types of batteries are going to be installed and if they are the
flooded/vented type or sealed type. - ____Show on plans how many batteries are to be installed, how they are connected (in series or
parallel), specify the voltage of each battery, and note the total battery bank voltage. Total
battery system voltage in a residential home is typically limited to 100 volts unless the live parts
of the batteries are not accessible during routine battery maintenance (NEC 706.20(B)).
General Equipment and Wiring Requirements (note: energy storage systems come in all different
layouts and configurations – as such, not all below noted items apply to all systems)
- ____Detailed manufacturer’s installation instructions and requirements for the ESS system must
be submitted for plan review and all requirements must be followed when installing the system.
Utah Amendment IRC R328.3 and NEC 110.3(B). - ____Provide manufacturer’s info indicating that the battery inverter is listed as being utility
interactive (if grid-tied) and be listed per UL 1741. Utah Amendment IRC R328.6, NEC 705.40,
NEC 706.5, NEC 706.16(B) and (C). - ____Please provide documentation for the energy storage system to show that such system has
been tested and listed per UL 9540. Utah Amendment IRC R328.2, NEC 706.5, and NEC Annex
A. - ____If the batteries are to be the NON-lead-acid type, please provide manufacturer specification
sheets for the batteries and show that they are listed per UL 1973. NEC 706.5 - ____If the same inverter is to be used for the solar PV system and the battery system (which is
often referred to as a DC coupled system), please show that the inverter contains DC ground fault
protection, as required per NEC 690.41(B). - ____If the same inverter is to be used for the solar PV system and the battery system and there are
DC voltages over 80 volts for the solar PV portion of the system, please show that the inverter
contains DC arc-fault protection, as required per NEC 690.11 (unless the exception applies). - ____Inverter manufacturer spec sheets must note the maximum allowable DC voltages of the
energy storage system and include the maximum DC voltage of the solar PV system if a PV DC
system will directly connect to the inverter. NEC 110.3(B). - ____For systems where the terminals of the batteries are exposed, specify on the plans that all
batteries must be located inside a lockable enclosure or room (guarded against accidental contact
by persons). NEC 110.27(A). - ____If flooded (vented) batteries will be used for the system, provide information on how the
battery enclosure will be ventilated. NEC 706.20(A) requires provisions appropriate to the
battery technology shall be made for sufficient diffusion and ventilation of the gases from the
battery, if present, to prevent the accumulation of an explosive mixture. (Note: see battery
manufacturer recommendations for any ventilation requirements) - ____If any charge controllers are to be installed for the battery system, please provide
manufacturer spec sheets for such and also show that the charge controller(s) is/are listed in
accordance with UL 1741. NEC 706.5, 706.33, and 110.3(B). Charge controllers must be
installed per manufacturer requirements where required per the ESS manufacturer. - ____There must be provided a sign or marking next to the ESS system disconnect with the sign
having the words “ENERGY STORAGE SYSTEM DISCONNECT.” The sign must also include
the Nominal AC voltage and maximum DC voltage of the ESS system. NEC 706.15(C). - ____Any ESS disconnects that have line and load terminals that may be energized in the open
position must have a sign or marking with the following words or equivalent: “WARNING,
ELECTRIC SHOCK HAZARD, TERMINALS ON THE LINE AND LOAD SIDES MAY BE
ENERGIZED IN THE OPEN POSITION.” NEC 706.15(C)
Point of Interconnection Requirements (Rules for back-fed panelboards): If the ESS is listed as
utility interactive having the capability to provide power from the ESS to the electric utility, and the ESS
system is connected to the home’s electrical system that is also connected to an electric utility, please see
the point of interconnection requirements noted in either the micro inverter solar PV system or string
inverter solar PV system plan review checklists. The ESS must comply with the applicable requirements
of NEC Article 705. Note: not all ESS have the capability to export battery power (after converting the
power to AC) onto the electric utility grid.
Utah Amendments for Energy Storage Systems (ESS) – These requirements must be
addressed in addition to all other applicable requirements noted in this plan review checklist:
Note: for a direct link to Utah State Code Amendments 15A-3-202, see the following: https://le.utah.gov/xcode/Title15A/Chapter3/15A-3-S202.html
IRC Definition of an Energy Storage System (ESS) is as follows: “One or more devices,
assembled together, that are capable of storing energy for supplying electrical energy at a future
time.”
- ____R328.1 General. Energy storage systems (ESS) shall comply with the provisions of this
section.
a. Exception 1: ESS listed and labeled in accordance with UL 9540 and marked “For use in
residential dwelling units”, where installed in accordance with the manufacturer’s
instructions and NFPA 70.
b. Exception 2: ESS less than 1 kWh (3.6 megajoules) - ____R328.2 Equipment listings. ESS shall be listed and labeled in accordance with UL 9540.
a. Exception: Where approved, repurposed unlisted battery systems from electric vehicles
are allowed to be installed outdoors or in detached sheds located not less than 5 feet
(1524 mm) from exterior walls, property lines and public ways. - ____R328.3 Installation. ESS shall be installed in accordance with the manufacturer’s instructions
and their listing. - ____R328.3.1 Spacing. Individual units shall be separated from each other by not less than three
feet (914 mm) except where smaller separation distances are documented to be adequate based on
large scale fire testing complying with Section 1206.2.3 of the adopted International Fire Code.
(Note: Large-scale fire testing is based on UL 9540A testing.) - ____R328.4 Locations. ESS shall be installed only in the following locations:
a. Detached garages and detached accessory structures.
b. Attached garages separated from the dwelling unit living space in accordance with
Section R302.6.
c. Outdoors or on the exterior side of exterior walls located not less than 3 feet (914 mm)
from doors and windows directly entering the dwelling unit.
d. Enclosed utility closets, basements, storage or utility spaces within dwelling units with
finished or noncombustible walls and ceilings. Walls and ceilings of unfinished wood wallboard.
ESS shall not be installed in sleeping rooms, or closets or spaces opening directly into
sleeping rooms. - ____R328.5 Energy ratings. Individual ESS units shall have a maximum rating of 20 kWh. The
aggregate rating of the ESS shall not exceed:
a. 40 kWh within utility closets, basements, and storage or utility spaces.
b. 80 kWh in attached or detached garages and detached accessory structures.
c. 80 kWh on exterior walls.
d. 80 kWh outdoors on the ground.
ESS installations exceeding the permitted individual or aggregate ratings shall be installed in
accordance with Section 1207 of the International Fire Code.
(NOTE: multiple systems, each in different locations, could have capacity ratings up to the
above noted values (per R328.5). For example, there could be up to an 80kWh system in the
attached garage, up to a 40kWh system inside a storage room in the house, and up to an
80kWh system in a detached building (if the provisions of R328.4 are met for each system)). - ____R328.6 Electrical installation. ESS shall be installed in accordance with NFPA 70. Inverters
shall be listed and labeled in accordance with UL 1741 or provided as part of the UL 9540 listing.
Systems connected to the utility grid shall use inverters listed for utility interaction. (Note: NFPA
70 is the National Electrical Code) - ____R328.7 Fire detection. Rooms and areas within dwelling units, basements, and
atta garages in which ESS are installed shall be protected by smoke alarms in accordance with Section
R314. A heat detector, listed and interconnected to the smoke alarms, shall be installed in
locations within dwelling units and attached garages where smoke alarms cannot be installed
based on their listing. - ____R328.8 Protection from impact. ESS installed in a location subject to vehicle damage shall be
protected by approved barriers. - ____R328.9 Ventilation. Indoor installation of ESS that include batteries that produce hydrogen or
other flammable gases during charging shall be provided with mechanical ventilation in
accordance with Section M1307.4. (Note: typically flooded or vented batteries are the type where
hydrogen is released during normal charging of the batteries.) - ____R328.10 Electric vehicle use. The temporary use of an owner or occupant’s electric powered
vehicle to power a dwelling unit while parked in an attached or detached garage or outdoors shall
comply with the vehicle manufacturer’s instructions and NFPA 70 (i.e. National Electrical
Code). - ____R328.1 Signage. A sign located on the exterior of the dwelling shall be installed at a
location approved by the authority having jurisdiction which identifies the battery chemistry
included in the ESS. This sign shall be of sufficient durability to withstand the environment
involved and shall not be handwritten.
Electrical Service Upgrades
- ____If the home’s service panel will be upgraded, please clearly specify on the line diagram the
exact model number of the new service panel you are going to install and provide manufacturer
specification sheets for such service panelboard. Such information is required in order to verify
compliance with the requirements of NEC 705.11 or 705.12 for the interconnection of the PV
system. Also, the authority having jurisdiction (AHJ) has the authority to determine if the existing
service equipment for the home is required to be upgraded. NEC 110.3(A). - ____If the service panelboard will be upgraded, then the new service panel must be shown to
comply with the requirements of NEC 230.71 and 230.62(C). Such requirements specify that the
new service panelboard can only have one main service breaker (to shut off all other breakers in
such new service panel) and there essentially cannot be any other supply-side breaker slots in the
new service panel. This requirement ONLY applies to new service equipment to be installed. It
does NOT apply to existing service panelboards that do not require upgrading.
Point of Interconnection Requirements (rules for backfed panelboards) – Note: the following items
may not be required for ESS that are completely stand-alone and not connected to any other
primary source of power (such as an electric utility, for example).
- ____Provide photos of the service panelboard and any back-fed sub-panelboards, and provide
photos of all panelboard’s interior labels. Photos must be with the panelboard’s front covers open
and show the ratings of all breakers therein. The photos of labels must also clearly show the
rating of the panelboard. These photos are essential to determining if the requirements of NEC
705.11 or 705.12 are going to be met. - ____If the ESS is to back-feed an AC breaker on the supply side (service side) of the home’s main
service breaker(s) (in existing service equipment), then the rating of the back-fed AC breaker
cannot exceed what is allowed to be plugged into the breaker slot (noted on the panelboard label),
and also cannot exceed the rating of the service conductors (wires) for the home. NEC 705.1(A)
and 110.3(B). - ____Factory installed conductors (wires) or bubars within a service panelboard cannot be tapped
unless such taps are allowed by the service panel manufacture (documentation from the service
equipment manufacturer is required to prove this), or if the service equipment is to be field
evaluated and approved by a listed testing agency (such as UL, Intertek, etc.). The connections
must be per the listing of the panelboard. NEC 110.3(B) and 705.11(D). - ____If taps will be made to non-factory-installed conductors between the utility meter base and
service disconnect for the building (ie. supply-side taps), then each of the following must be
specified on the plans:
a. Please specify that the fused disconnect switch (which protects the tap wires) must be
listed and labeled as “suitable for use as service equipment.” This is required per NEC
705.11, 230.82(6), and 230.66.
b. Since the fused PV disconnect is to be considered as a service disconnect, please also
specify that there must be a main bonding jumper within such enclosure and specify the
size and type of such main bonding jumper. This is in accordance with NEC 250.24 and
250.25.
c. The ground wire within the conduit between the disconnect switch and the main service
equipment will be considered as the grounding electrode conductor (GEC) for the
disconnect service equipment (see NEC 250.24(D)). As such, please note on the plans
that the GEC must be bonded to each end of the metal conduit, as required per NEC
250.64(E).
d. The supply-side tap conductors (wires) leading from the fused disconnect to the point of
taps at the service cannot be less than #6 AWG copper (or #4 AWG aluminum) and such
tap conductors must be installed per NEC 230.30. See NEC 705.11(B). The conductors
also cannot be smaller than what is required per NEC 705.28 (i.e. which is usually 125%
multiplied by the output ampacity rating of the inverter(s)).
e. The disconnect must be located on either the outside of the home or the first readily
accessible location inside the home where the tap conductors first enter the building
(unless item 705.11(C)(1) is met). See NEC 705.11(C). - ____If a meter adapter is going to be used for the connection of the ESS system to the supply-side
of the service disconnect(s), please provide manufacture specification sheets and installation
instructions for such meter adapter. Documentation must also be provided to show that the meter
adapter is listed in accordance with UL 414. NEC 110.3. - ____If the ESS is to back-feed electrical equipment on the load side (the home’s side of the main
service breaker(s)), then the following must be addressed:
(note: instead of using 125% of the output current rating of the ESS inverter(s), if
there is a PCS system (Power Control System) then it is permissible to use 125% of
the ampacity output setting of the PCS equipment instead of the amp rating of the
inverter(s) – See NEC 705.12):
For protection of feeder wires, ONE of the following items (‘a’ through ‘d’ shown
below) must be met:
a. If the ESS will be connected to the end of feeder wires opposite to the feeder wire’s main
breaker, then the feeder wires must have an ampacity not less than the main breaker for
the feeders or 125% of the inverter(s) AC output current (amps), whichever is larger. See
first sentence of NEC 705.12(B)(1).
b. If the PV system will not be connected to the end of feeder wires opposite to the feeder
wire’s main breaker, then the feeder wires must have an ampacity not less than 125% of
the AC output current (amps) of the ESS inverter plus the rating of the main breaker
protecting the feeder wires. See NEC 705.12(B)(1)(a).
c. If the ESS will not be connected to the end of feeder wires opposite to the feeder wire’s
main breaker, then an overcurrent protection device (fuses or breaker) which is/are rated
not more than the ampacity of the feeder wires must be provided on the load side of the
ESS inverter’s AC output connection to the feeders. See NEC 705.12(B)(1)(b).
d. If the ESS back-fed breaker will be connected to busbars which have feeder wires
connected to feed-through lugs on the same busbars as the ESS breaker, then either of
the plan review requirements per items 56-b or 56-c (shown above in this checklist) must
be complied with for protecting the feeder wires that are connected to the feed-through
lugs (see NEC 705.12(B)(3)(6)).
For protection of panelboard’s busbars, ONE of the following items (‘e’ through ‘h’
shown below) must be met:
e. The busbars must be rated not less than the main breaker (or fuses) protecting the
panelboard plus 125% of the AC output current (amps) of the ESS inverter(s). See NEC
705.12(B)(3)(1).
f. If the inverter’s AC breaker is located at the very end of the panelboard’s busbars (at the
opposite end of where the panel is fed from for the utility source), then the rating of the
main breaker (or fuses) protecting the panelboard plus 125% of the inverter’s AC output
current (amps) cannot exceed 120% of the rating of the panelboard’s busbars. See NEC
705.12(B)(3)(2). If this NEC code item is to be utilized, then please specify that a sign is
required at the PV back-fed breaker location noting the following: “WARNING,
INVERTER OUTPUT CONNECTION, DO NOT RELOCATE THIS OVERCURRENT
DEVICE.”
g. The busbars in the panelboard must be rated not less than the sum of the ratings of all
breakers in the panelboard, including the ESS breaker but not counting the main breaker
(or fuses) protecting the panelboard. If this NEC code item is to be used for the
interconnection of the ESS, there must also be a sign located at the panelboard noting the
following: “WARNING: THIS EQUIPMENT FED BY MULTIPLE SOURCES.
TOTAL RATING OF ALL OVERCURRENT DEVICES, EXCLUDING MAIN
OVERCURRENT DEVICE, SHALL NOT EXCEED AMPACITY OF BUSBAR.” See
NEC 705.12(B)(3)(3).
h. ESS connections to multiple-ampacity busbars or to a center-fed panelboard is permitted
as long as the ESS back-fed breaker is in either the very top or the very bottom slot of the
center-fed panelboard, AND the rating of the main breaker (or fuses) protecting the
panelboard plus 125% of the inverter’s AC output current (amps) cannot exceed 120% of
the rating of the panelboard’s busbars. See NEC 705.12(B)(3)(4). The rating of the ESS
back-fed breaker cannot exceed the rating of the breaker slot that it will be plugged into
(as noted per the panelboard’s label). - ____If feeder taps are to be performed in order to connect the ESS system to the electrical system
of the home, then the tap rules of NEC 240.21(B) must be followed (in addition to those found
under NEC 705.12(B)(1)). See also the above requirements for connections on the load side of the
service disconnect(s). - ____If a Power Control System (PCS) is to be used for this project, documentation must be
provided to show that the equipment is listed as such and the requirements of NEC 705.13 must
be addressed.