{"operation":"document","citation":"25-0145","title":"Fluence — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2026-01-29","effective_on":null,"summary":"25-0145 response to Fluence concerning 171.1, 172.102, 172.332.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0145.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0145.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0145","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-02/25-0145.pdf","body":"<<>>\n\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nJanuary 29, 2026\nAnna Stephens\nSr. Commodity Manager, Logistics\nFluence\n1725 Windward Concourse #420\nAlpharetta, GA 30005\nReference No. 25-0145\nDear Ms. Stephens:\nThis letter is in response to your October 3, 2025 email requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) applicable to the transport of lithium ion\nbatteries in cargo transport units (CTUs).\nWe have paraphrased and answered your questions as follows:\nQ1. Are placards required when shipping an energy storage system classified as “UN3536,\nLithium batteries installed in cargo transport unit, 9.” If the answer is yes, what type of\nplacards are required to be placed on the CTU?\nA1. Yes. As provided in Special Provision (SP) 389 in § 172.102, a CTU must display the\nUN number in a manner in accordance with § 172.332 and be placarded on two opposing\nsides with a Class 9 placard.\nQ2. If placarded, is the driver of a motor vehicle transporting an energy storage system\nclassified as “UN3536, Lithium batteries installed in cargo transport unit, 9” required to\nhave a hazmat endorsement on his or her commercial driver’s license (CDL).\nA2. The endorsement requirements for a CDL (see 49 CFR Part 383.91(a)(3)) are under the\npurview of the Federal Motor Carrier Safety Administration (FMCSA). FMCSA is the\nlead federal government agency responsible for regulating and providing safety oversight\nof commercial motor vehicles. You may wish to contact FMCSA should you require\nclarification of any requirements relevant to CDLs.\nQ3. Are there any rulemaking proposals to require the placarding of an energy storage system\nclassified as “UN3536, Lithium batteries installed in cargo transport unit, 9” under\nsubpart F of 49 CFR part 172.\n\n<<>>\n\nA3. No rulemakings are in progress to revise the placarding requirements applicable to\nlithium batteries in CTUs. See answer A1.\nQ4. What are the requirements for fire extinguishers that are necessary within the CTU, as\nprovided in SP 389?\nA4. In accordance with SP 389, hazardous materials necessary for the safe and proper\noperation of the CTU (e.g., fire extinguishing systems and air conditioning systems) must\nbe properly secured to or installed in the CTU and are not otherwise subject to the HMR.\nHowever, packagings (e.g., a DOT specification cylinder) represented as meeting\nrequirements of the HMR governing their use in the transportation of a hazardous\nmaterial must be so maintained unless representative marks are obliterated or covered\n(see § 171.1(g)).\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nDirk Der Kinderen\nChief, Standards Development Branch\nStandards and Rulemaking Division\n\n<<>>\n\nCasey, C.\n25-0145\nFrom: Andrews, Steven (PHMSA)\nTo: Baker, Yul (PHMSA)\nCc: Nickels, Matthew (PHMSA)\nSubject: FW: Fluence Energy - cargo: enclosures with lithium ion batteries UN3536 class 9 and domestic transportation\nDate: Friday, November 14, 2025 6:36:24\nAttachments: image001.png\nimage002.png\nimage003.png\n00SY-SDS-ENC-80-001 Enclosure Safety Datasheet Collection for Gridstack Pro 5000 1.pdf\nScreenshot 2025-10-02 160517.png\nHey Yul,\nCan you put this one into the system as well?\nThanks,\nSteven Andrews\nActing Senior Regulations Officer\nOffice of Hazardous Materials Standards\nStandards and Rulemaking Division\nUS Department of Transportation\nPipeline and Hazardous Materials Safety Administration\n1200 New Jersey Ave, SE, Washington, D.C. 20590\nOffice: 202.536.9778\nPHMSA Home | LinkedIn | Twitter | HAZMAT | OPS\nFrom: Anna Stephens \nSent: Friday, October 3, 2025 10:17 AM\nTo: Andrews, Steven (PHMSA) \nSubject: Fluence Energy - cargo: enclosures with lithium ion batteries UN3536 class 9 and domestic\ntransportation\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\nis safe.\nHello Mr Andrews,\nWe have another product we ship domestically, which is fully populated enclosure with lithium-ion\nbattery installed in it. Its calling under UN3536 Class 9.\nWe would like to get the answers and interpretation to our questions in a formal way. That will help\nus to provide the letter to our service providers that move these products for us in case of random\ninspection while in route.\n\n<<>>\n\nProduct name: Fully populated enclosures with lithium-ion batteries / UN No. UN 3536 / Proper\nShipping Name: Lithium batteries installed in cargo transport unit / Class: 9 / Special Provision:\n389 à MSDS in attachment 2\nQ1: You ask whether placards are required when shipping an energy storage system classified as\n“UN3536, Lithium batteries installed in cargo transport unit, 9.” And if so what type of placards\nare required to be placed on units?\nQ2: You ask whether the driver of a motor vehicle transporting an energy storage system\nclassified as “UN3536, Lithium batteries installed in cargo transport unit, 9” is required to have a\nhazmat endorsement on his or her Commercial Driver’s License (CDL).\nQ3: You ask whether the Pipeline and Hazardous Materials Administration (PHMSA) have any\ncurrent proposals to require the placarding of an energy storage system classified as “UN3536,\nLithium batteries installed in cargo transport unit, 9” under Subpart F of 49 CFR Part 172.\nQ4: During recent random inspection while in route one of the drivers was asked by DOT officer\nthat fire extinguishers are necessary within the unit. Can you elaborate more on how to interpret\nAttachment 1 (driver was shown the page)? We confirm the enclosures have built cooling system\nwith chiller and HVAC system however they are not operational during transportation.\nThank you for your help as always.\nBest regards,\nAnna Stephens | Sr. Commodity Manager, Logistics\nFluence - A Siemens and AES Company\nEmail: anna.stephens@fluenceenergy.com\nCell#: 404-825-4082\n1725 Windward Concourse #420 | Alpharetta, GA | USA\nFrom: Andrews, Steven (PHMSA) \nSent: Wednesday, September 10, 2025 2:00 PM\nTo: Anna Stephens \nSubject: RE: Fluence Energy - cargo: lithium ion battery modules and cells UN3480 class 9 and\ndomestic transportation\nCAUTION: This email originated from outside the organization. Do not click links or\nopen attachments unless you recognize the sender and know the content is safe.\nHi Anna,\nNo cost to getting official letters of interpretations, but they do have to get in the queue line with\n\n<<>>\n\nthe other request. May take several weeks. you want to take,\nHappy to forward to the interp team if that’s the route\nThanks,\nSteven Andrews\nActing Senior Regulatory Officer\nOffice of Hazardous Materials Standards\nStandards and Rulemaking Division\nUS Department of Transportation\nPipeline and Hazardous Materials Safety Administration\n1200 New Jersey Ave, SE, Washington, D.C. 20590\nOffice: 202.536.9778\nPHMSA Home | LinkedIn | Twitter | HAZMAT | OPS\nFrom: Anna Stephens \nSent: Monday, September 8, 2025 2:19 PM\nTo: Andrews, Steven (PHMSA) \nSubject: RE: Fluence Energy - cargo: lithium ion battery modules and cells UN3480 class 9 and\ndomestic transportation\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\nis safe.\nHello Sir,\nApologies for delayed response. I was out of packet last week. So does that mean there\nwill be cost associated with it?\nI don’t have supporting MSDS available yet for Fluence modules but working on it. I\nsuspect it will be needed to support our request, correct?\nBest regards,\nAnna Stephens | Sr. Commodity Manager, Logistics\nFluence - A Siemens and AES Company\nEmail: anna.stephens@fluenceenergy.com\nCell#: 404-825-4082\n\n<<>>\n\n1725 Windward Concourse #420 | Alpharetta, GA | USA\nFrom: Andrews, Steven (PHMSA) \nSent: Wednesday, September 3, 2025 12:22 PM\nTo: Anna Stephens \nSubject: RE: Fluence Energy - cargo: lithium ion battery modules and cells UN3480 class 9 and\ndomestic transportation\nCAUTION: This email originated from outside the organization. Do not click links or\nopen attachments unless you recognize the sender and know the content is safe.\nHi Anna,\nAny formal responses on letterhead would have to be vetted through our letters of interpretation\nprocess which goes through a technical and legal review. Would you like me to forward your request\nto the letters of interpretation team?\nThanks,\nSteven Andrews\nTransportation Specialist, Regulatory Review and Reinvention Branch\nPetitions Coordinator, Information Collection Officer\nOffice of Hazardous Materials Standards\nStandards and Rulemaking Division\nUS Department of Transportation\nPipeline and Hazardous Materials Safety Administration\n1200 New Jersey Ave, SE, Washington, D.C. 20590\nOffice: 202.536.9778\nPHMSA Home | LinkedIn | Twitter | HAZMAT | OPS\nFrom: Anna Stephens \nSent: Friday, August 29, 2025 3:24 PM\nTo: Andrews, Steven (PHMSA) \nSubject: RE: Fluence Energy - cargo: lithium ion battery modules and cells UN3480 class 9 and\ndomestic transportation\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\n\n<<>>\n\nis safe.\nHello mr Andrews,\nI hope all is well. Is it possible to get your response on your letter head regarding\nexemptions for lithium-ion battery modules and cells UN3480 class 9 not considered\nhazardous for domestic transportation?\nWe would like to have it for our record retention specifying our cargo.\nQ1: Are placards required when shipping Lithium-ion batteries and cells under UN3480, class 9 ?\nif so what type of placards should be used?\nQ2: Is driver of a motor vehicle transporting a Lithium-ion batteries under UN3480, class 9\nrequired to have a hazmat endorsement on his or her Commercial Driver’s License (CDL).\nBest Regards,\nAnna Stephens \nFrom: Andrews, Steven (PHMSA) \nSent: Monday, May 5, 2025 10:39 AM\nTo: Anna Stephens \nSubject: RE: Fluence Energy - cargo: lithium ion battery modules and cells UN3480 class 9 and\ndomestic transportation\nCAUTION: This email originated from outside the organization. Do not click links or\nopen attachments unless you recognize the sender and know the content is safe.\nGood Morning Anna,\nSee attached. We have letters of interpretation stating that Class 9 materials do not trigger CDL\nrequirements.\nThanks,\nSteven Andrews\nTransportation Specialist, Regulatory Review and Reinvention Branch\nPetitions Coordinator, Information Collection Officer\nOffice of Hazardous Materials Standards\nStandards and Rulemaking Division\n\n<<>>\n\nUS Department of Transportation\nPipeline and Hazardous Materials Safety Administration\n1200 New Jersey Ave, SE, Washington, D.C. 20590\nOffice: 202.366.6199\nPHMSA Home | LinkedIn | Twitter | HAZMAT | OPS\nFrom: Anna Stephens \nSent: Friday, May 2, 2025 12:51 PM\nTo: Andrews, Steven (PHMSA) ; PHMSA Public Affairs\n\nSubject: Fluence Energy - cargo: lithium ion battery modules and cells UN3480 class 9 and domestic\ntransportation\nSome people who received this message don't often get email from anna.stephens@fluenceenergy.com. Learn why this\nis important\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\nis safe.\nHello mr Andrews,\nI am reaching out to you to get your clarification about transporting over the road lithium-\nion battery modules and battery cells under UN3480 Class 9.\nIs this commodity exempt from being considered as hazmat and driver is not required to\nhold a hazmat endorsement on his or her Commercial Driver’s License (CDL), or this\ntype of commodity is not exempt and considered as hazardous for the domestic\ntransportation.\nMSDS for the mentioned commodity is attached.\nThank you for your comments.\nBest Regards,\nAnna Stephens \nFrom: Andrews, Steven (PHMSA) \nSent: Thursday, March 20, 2025 6:52 PM\n\n<<>>\n\nTo: Anna Stephens \nSubject: RE: Fluence Energy - cargo: lithium ion batteries UN3536 class 9 and domestic\ntransportation\nCAUTION: This email originated from outside the organization. Do not click links or\nopen attachments unless you recognize the sender and know the content is safe.\nHi Anna,\nGood to hear from you. No recent changes in the HMR would change anything in the 2021 letter of\ninterpretation or email I sent last year.\nFeel free to reach out in the future for any updates. In addition if we release a rule that changes\nanything concerning “UN3536, Lithium batteries installed in cargo transport unit, 9” I’ll try to remember to\nemail you about it.\nThanks,\nSteven Andrews\nTransportation Specialist, Regulatory Review and Reinvention Branch\nPetitions Coordinator, Information Collection Officer\nOffice of Hazardous Materials Standards\nStandards and Rulemaking Division\nUS Department of Transportation\nPipeline and Hazardous Materials Safety Administration\n1200 New Jersey Ave, SE, Washington, D.C. 20590\nOffice: 202.366.6199\nPHMSA Home | LinkedIn | Twitter | HAZMAT | OPS\nFrom: Anna Stephens \nSent: Thursday, March 20, 2025 12:35 PM\nTo: Andrews, Steven (PHMSA) ; PHMSA Public Affairs\n\nSubject: RE: Fluence Energy - cargo: lithium ion batteries UN3536 class 9 and domestic\ntransportation\nSome people who received this message don't often get email from anna.stephens@fluenceenergy.com. Learn why this\nis important\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\nis safe.\n\n<<>>\n\nGood day,\nI connected with officer Andrews last year asking to get an update on lithium-ion batteries UN3536 class 9\nand domestic transportation. And we had received back in 2021 official letter, the letter couldn’t be updated\nlast year so we used attached email supporting the letter from 2021.\nToday, we have a new product (lithium-ion batteries installed in cargo transport unit) that still falls under the\nsame class, so we just wanted to get an update from your side regarding exemptions for transporting these\nunits without drivers holding a hazmat license.\nAlso, if PHMSA has any implemented any new ruling that requires the placarding of an energy storage system\nclassified as “UN3536, Lithium batteries installed in cargo transport unit, 9” under Subpart F of 49 CFR Part\n172.\nThank you in advance for your feedback.\nBest Regards,\nAnna Stephens \nFrom: Andrews, Steven (PHMSA) \nSent: Wednesday, March 20, 2024 9:28 AM\nTo: Anna Stephens \nSubject: RE: Fluence Energy - cargo: lithium ion batteries UN3536 class 9 and domestic\ntransportation\nCAUTION: This email originated from outside the organization. Do not click links or open\nattachments unless you recognize the sender and know the content is safe.\nAnna,\nJust FYI, I got some word that we do want to investigate this Letter of Interpretation a little further. I\nwill let you know as soon as I can that my statement below is still true. One person in my office saw\nyour request and just wants to doublecheck that we stand by this letter entirely.\nThank you,\nSteven Andrews\nActing Chief, Regulatory Review and Reinvention Branch\nOffice of Hazardous Materials Standards\nStandards and Rulemaking Division\nUS Department of Transportation\nPipeline and Hazardous Materials Safety Administration\n1200 New Jersey Ave, SE, Washington, D.C. 20590\nOffice: 202.366.6199\n\n<<>>\n\nPHMSA Home | LinkedIn | Twitter | HAZMAT | OPS\nFrom: Anna Stephens \nSent: Tuesday, March 19, 2024 4:59 PM\nTo: Andrews, Steven (PHMSA) \nSubject: RE: Fluence Energy - cargo: lithium ion batteries UN3536 class 9 and domestic\ntransportation\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\nis safe.\nThank you Sir. I will use your email then.\nBest Regards,\nAnna Stephens \nFrom: Andrews, Steven (PHMSA) \nSent: Tuesday, March 19, 2024 3:05 PM\nTo: Anna Stephens \nSubject: RE: Fluence Energy - cargo: lithium ion batteries UN3536 class 9 and domestic\ntransportation\nYou don't often get email from steven.andrews@dot.gov. Learn why this is important\nCAUTION: This email originated from outside the organization. Do not click links or open\nattachments unless you recognize the sender and know the content is safe.\nHi Anna,\nWe don’t typically issue reprints of the same letter. That being said I can put everything in a email\nbelow that you can print. I am the acting chief right now, so I’ll add my signature block to the end of\nthis email so people can see that I confirmed this is current for PHMSA/OHMS.\nSee PHMSA’s answers to the following questions as they related to Letter of Interpretation 21-0099.\nPHMSA is repeating the questions and answers below and noting that as of March 19, 2024 these\nanswers are still current:\n\n<<>>\n\nQ1: You ask whether placards are required when shipping an energy storage system classified as\n“UN3536, Lithium batteries installed in cargo transport unit, 9.”\nA1: The answer is yes. Special provision 389 is assigned to that proper shipping name and states that\n“the cargo transport unit shall display the UN number in a manner in accordance with § 172.332 of\nthis subchapter and be placarded on two opposing sides.”\nQ2: You ask whether the driver of a motor vehicle transporting an energy storage system\nclassified as “UN3536, Lithium batteries installed in cargo transport unit, 9” is required to have a\nhazmat endorsement on his or her Commercial Driver’s License (CDL).\nA2: The answer is no. For purposes of 49 CFR Part 383 and the applicability of the CDL hazmat\nendorsement, a “hazardous material” is defined in 49 CFR 383.5 as a material that has been\ndesignated as hazardous under 49 U.S.C. 5103 and is required to be placarded under Subpart F of 49\nCFR Part 172; or any quantity of a material listed as a select agent or toxin in 42 CFR Part 73. In your\nscenario, the cargo transport unit does not require placards under Subpart F of 49 CFR Part 172 (see\n§ 172.504(f)(9)).\nQ3: You ask whether the Pipeline and Hazardous Materials Administration (PHMSA) has any\ncurrent proposals to require the placarding of an energy storage system classified as “UN3536,\nLithium batteries installed in cargo transport unit, 9” under Subpart F of 49 CFR Part 172.\nA3: The answer is no, PHMSA has no such proposals under consideration at this time. If you believe a\nrulemaking change is warranted, we invite you to file a petition for rulemaking in accordance with 49\nCFR 106.95, 106.100, and 106.105, including all information needed to support your petition. Your\nrequest will be evaluated for consideration in a future upcoming rulemaking. For regulations in 49\nCFR Parts 171 through 180, please submit the petition to: Standards and Rulemaking Division,\nPipeline and Hazardous Materials Safety Administration, PHH-10, U.S. Department of Transportation,\nEast Building, 1200 New Jersey Avenue, SE, Washington, DC 20590-0001. Please contact Mr. Steven\nAndrews in the Regulatory Review and Reinvention Branch of the Standards and Rulemaking Division\nat 202-366-8553 for more information.\nSteven Andrews\nActing Chief, Regulatory Review and Reinvention Branch\nOffice of Hazardous Materials Standards\nStandards and Rulemaking Division\nUS Department of Transportation\nPipeline and Hazardous Materials Safety Administration\n1200 New Jersey Ave, SE, Washington, D.C. 20590\nOffice: 202.366.6199\nPHMSA Home | LinkedIn | Twitter | HAZMAT | OPS\n\n<<>>\n\nFrom: Anna Stephens \nSent: Tuesday, March 19, 2024 2:55 PM\nTo: Andrews, Steven (PHMSA) \nSubject: RE: Fluence Energy - cargo: lithium ion batteries UN3536 class 9 and domestic\ntransportation\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\nis safe.\nDear Mr Andrews,\nThank you very much for your prompt response. Since we are conducting an annual RFQ with our\ntransportation providers\nwill it be possible to ask for updated letter from you covering the same? I will greatly appreciate it.\nBest Regards,\nAnna Stephens \nFrom: Andrews, Steven (PHMSA) \nSent: Tuesday, March 19, 2024 2:49 PM\nTo: Anna Stephens \nSubject: RE: Fluence Energy - cargo: lithium ion batteries UN3536 class 9 and domestic\ntransportation\nYou don't often get email from steven.andrews@dot.gov. Learn why this is important\nCAUTION: This email originated from outside the organization. Do not click links or open\nattachments unless you recognize the sender and know the content is safe.\nHi Anna,\nThere have been no changes to the HMR that would change the answers to the letter we provided\nyou in 2021. The same answers in your email apply as they applied in the 2021 letter. We have not\nimplemented any revisions to the HMR since then that would change these answers.\nLet me know if you have any other questions.\nThanks,\nSteven Andrews\nActing Chief, Regulatory Review and Reinvention Branch\nOffice of Hazardous Materials Standards\n\n<<>>\n\nStandards and Rulemaking Division\nUS Department of Transportation\nPipeline and Hazardous Materials Safety Administration\n1200 New Jersey Ave, SE, Washington, D.C. 20590\nOffice: 202.366.6199\nPHMSA Home | LinkedIn | Twitter | HAZMAT | OPS\nFrom: Anna Stephens \nSent: Tuesday, March 19, 2024 1:50 PM\nTo: PHMSA Public Affairs \nSubject: Fluence Energy - cargo: lithium ion batteries UN3536 class 9 and domestic transportation\nSome people who received this message don't often get email from anna.stephens@fluenceenergy.com. Learn\nwhy this is important\nCAUTION: This email originated from outside of the Department of Transportation (DOT). Do\nnot click on links or open attachments unless you recognize the sender and know the content\nis safe.\nGood day,\nMy name is Anna Stephens and I am with Fluence Energy, the energy storage company. We are the\nowners of lithium-ion batteries under UN3536 class 9 that we ship individually but also as built into\ncubes as battery storage units.\nOur company previous management reached out to your officials back in 2021 for clarification\naround this commodity and its domestic transportation.\nPlease see attached response letter from DOT PHMSA department with answers to Fluence\nquestions. We would like to ask if someone can provide an update on transportation this commodity\ntoday.\nFluence questions are:\n1. If placards are required when shipping an energy storage system classified as “UN3536,\nLithium batteries installed in cargo transport unit, 9.\n2. If the driver of a motor vehicle transporting an energy storage system classified as “UN3536,\nLithium batteries installed in cargo transport unit, 9” is required to have a hazmat\nendorsement on his or her Commercial Driver’s License (CDL).\n3. If PHMSA has any implemented any new ruling that requires the placarding of an energy\nstorage system classified as “UN3536, Lithium batteries installed in cargo transport unit, 9”\nunder Subpart F of 49 CFR Part 172.\nThank you in advance for your comments.\n\n<<>>\n\nBest regards,\nAnna Stephens | Sr. Commodity Manager, Logistics\nFluence - A Siemens and AES Company\nEmail: anna.stephens@fluenceenergy.com\n1725 Windward Concourse #420 | Alpharetta, GA | USA","truncated":false,"body_characters":24693}