TL;DNR Answer:
No, and it is not required to have one.
BackgroundSome inspectors require breaker bolt-downs for battery circuits, referencing NEC 408.36(D) as the source article. This article states: "Plug-in-type overcurrent protection devices or plug-in type main lug assemblies that are back-fed and used to terminate field installed ungrounded supply conductors shall be secured in place by an additional fastener that requires other than a pull to release the device from the panel." |
Detailed Explanation
Let's begin with relevant Code articles for situations where an inspector or installer insists that PV breakers must have a tie-down kit or bolt-down breaker. PV breakers have an exception to 480.36(D). The source article begins with 690.59 and eventually ends up at the relevant Code article.
690.59 Connection to Other Sources
PV systems connected to other sources shall be installed IAW Parts I and II of Article 705.
Ok, so now we turn to 705.12 Point of Connection
705.12(B)(5) Fastening (article subsection)
Listed plug-in-type circuit breakers backed from electric power sources that are listed and identified as interactive shall be permitted to omit the additional fastener normally required by 408.36(D).
Since the EI Inverter acts as an interactive inverter when the EI Battery is not installed, it does not need to comply with the fastening requirement. However, if we continue reading 705.12, we reach this section:
705.12(D) Back-Fed Devices
Plug-in-type overcurrent protection devices or plug-in type main lug assemblies that are backed and used to terminate field-installed ungrounded supply conductors shall be secured in place by an additional fastener that requires other than a pull to release the device from the mounting means on the panel.
This means ESS output circuits that power a backup panel must comply. PV inverters are exempt from bolt-down breakers because they are considered grid-following (listed and identified as interactive). If the PV inverter is producing power and someone pulls its breaker off the AC panel, the inverter will immediately disconnect and stop back-feeding into that breaker.
An ESS system uses an inverter listed as Multimode, sometimes referred to as a hybrid inverter like the EI Inverter. Contrary to their PV inverter cousins, multimode inverters include a grid-forming component. Hybrid inverters will not power down even if the breaker is pulled off the bus bar. The person who pulled off the breaker would be holding a live circuit. Due to this grid-forming behavior, ESS AC output breakers must comply with NEC 408.36(D). One could imply that since the EI Inverter is a multimode inverter, it would need to comply if installed with the EI Battery and the EI ATS. But let's look at that more closely.
Here is a simple line diagram of a complete EI energy storage system.
Notice the GRID output terminal of the EI Inverter is connected to the INVERTER breaker inside the EI ATS. During backup operation when the grid is down, the 200A breaker located on the right side of the ATS will not be backed by the EI Inverter. The inverter power is directed to the LOAD terminals.
| Perceptive customer: "AHA! So, the 200A breaker may not need a bolt-down breaker, but the ATS internal inverter breaker would." |
Even though the EI Inverter breaker inside the EI 200A ATS is fed by excess solar when the grid goes down, it does not have to comply with the bolt-down requirement. There is a built-in exception to 408.36(D):
"Plug-in-type overcurrent protection devices or plug-in type main lug assemblies that are back-fed and used to terminate field installed ungrounded supply conductors shall be secured in place by an additional fastener that requires other than a pull to release the device from the panel."
Notice the highlighted "field installed". Since the EI ATS internal inverter breaker is factory installed, it is still exempt from the bolt-down requirement.
Of course, none of this matters if your inspector or AHJ still requires the use of a bolt breaker regardless of the exceptions. Ignorance or misinterpretation of the Code may nullify the exceptions.
If you have any questions, please contact the Tigo Sales Engineering team: se@tigoenergy.com