Why Is There No EV-Specific SOLAS Fire Rule?

Because the evidence has not justified a rule keyed to battery chemistry, and the process that could write one has not reached drafting. The binding fire amendment in force since 1 January 2026 — Resolution MSC.550(108) — is deliberately fuel-agnostic and, as IUMI's own summary puts it, will mainly apply to new passenger ships. The IMO output aimed at new-energy vehicles, opened at MSC 105 in April 2022, decided at SSE 12 in March 2026 to write interim guidelines before any SOLAS text, with an amendment entering into force on 1 January 2032 at the earliest. A car carrier today is governed by neither.

What the 2026 rules actually regulate

Vehicle decks on passenger ships, without reference to what powers the vehicles. MSC.550(108), adopted 23 May 2024, requires individually identifiable smoke-and-heat detection throughout vehicle, special category and ro-ro spaces, detection sections matched to the deluge sections, video monitoring with seven days of playback, fixed water monitors and 125% drainage on weather decks used for vehicles, and new opening and safety-distance rules — for passenger ships constructed on or after 1 January 2026. Existing passenger ships, including those built before July 2012, pick up smoke-and-heat detection, 24-hour video and weather-deck monitors of at least 1,250 L/min at the first survey on or after 1 January 2028. Not one of those paragraphs mentions a battery, a state of charge or a vehicle type.

A cargo ship — which is what a pure car and truck carrier is — gets one paragraph. New paragraph 20.4.1.5, for cargo ships constructed on or after 1 January 2026, requires a fixed detection system complying with the FSS Code, capable of rapidly detecting the onset of fire and tested under normal ventilation. Cargo ships built before 2026 comply with the previously applicable text. The FSS Code minimum for a cargo ship remains section identification; the 2028 retrofit date does not occur in any paragraph a cargo ship is subject to.

Where the new-energy-vehicle work actually sits

At the guideline stage, four years in. MSC 105 added the output — "Evaluation of adequacy of fire protection, detection and extinction arrangements in vehicle, special category and ro-ro spaces in order to reduce the fire risk of ships carrying new energy vehicles" — in April 2022 and gave the SSE Sub-Committee four sessions, 2024 to 2027. SSE 11 in February 2025 agreed a five-part action plan: review the scientific reports, studies, new technologies and casualty reports; identify the hazards of new-energy vehicles compared with internal-combustion vehicles; consider a goal-based approach; identify gaps in the existing regulations; and identify placeholders for possible future amendments. A correspondence group carried the work to SSE 12.

SSE 12, in March 2026, revised the plan rather than drafting text. The Sub-Committee gave priority to two sets of interim guidelines — one on fire safety measures for pure car and truck carriers, one on video monitoring and detection systems — to be developed before any amendment to SOLAS, and sent the work to a correspondence group reporting to SSE 13 in March 2027. On that path, draft amendments could go to the Committee for approval and adoption in 2027 and enter into force on 1 January 2032 at the earliest. That is the vehicle-carrier rule, and it does not yet exist in draft.

Why IMO is not writing an 'EV rule'

Because the compiled evidence says the fire is broadly the same and the firefighting is not, and that split points to operational measures rather than a chemistry-keyed regulation. IUMI's September 2025 risk-mitigation paper, written for underwriters from the full-scale test literature, sets it out: the frequency of EV fires compared with conventional vehicles is currently estimated to be lower over the same distance driven; the total heat release of EV and ICE vehicle fires shows only a minor difference, so "EV fires are not more intense than ICEV fires", though the peak may be higher depending on battery type and state of charge; and roughly 20% of a modern car's fire load is its energy source against 80% plastics and interior, whichever the propulsion. The EU LASH FIRE project found a drencher has the same effect on the fire whether the source is an ICE vehicle or an EV.

What differs is the mechanism. IUMI is equally direct that once a traction battery is in thermal runaway no extinguishing medium can interrupt the chain reaction, that flammable gas may be released, and that the risk of re-ignition is higher for a longer period than for an ICE vehicle. Those are differences in dynamics, verification and post-fire handling — the things that drive procedure, ventilation, drencher duration and crew training — not differences that would make a fuel-blind detection and suppression floor the wrong floor. The SSE action plan's second pillar, hazards of new-energy vehicles compared with ICEVs, is the process for establishing that delta before anyone writes text against it.

What could still come out EV-specific

The interim guidelines, and probably only as guidance at first. The PCTC fire-safety guidelines are the first IMO instrument written for a car-carrier deck rather than a ferry deck, and they are where measures the ro-pax amendment never addressed — state of charge on loading, stowage of battery vehicles relative to suppression sections, off-gas detection, thermal screening at the ramp — could be written down with IMO authority behind them. The video-monitoring and detection guidelines are the place where a detection resolution better than section identification could be described for a cargo ship. Neither is a rule; both are the drafts a 2032 rule would be cut from, and both are being written now.

Meanwhile the fuel-specific rules that do exist are outside SOLAS Chapter II-2. The IMDG Code's UN 3556 entry for battery-electric vehicles took effect on 1 January 2026 and, through special provision 961, largely keeps a driven-on car out of dangerous-goods documentation; the state-of-charge ceiling that most lines apply is EMSA guidance and a booking condition, not a regulation. IUMI's own line is that no international requirement for state of charge in maritime transport has been agreed.

What this means for operators

Don't plan against an EV rule, and don't plan against a 2028 date unless you carry passengers. For a ro-pax the binding floor is real, dated and fuel-blind; the compliance plan should be the same. For a PCTC the SOLAS floor is the FSS Code minimum, the 2028 date belongs to someone else's fleet, and the pressure to fit detection beyond the minimum comes from insurers, charterers and class — which is where the EV-specific expectations live too. IUMI's conclusion to underwriters is the operative sentence for both: the time between detection and confirmation or verification must be reduced to the shortest possible period. That is a fuel-agnostic instruction, it is what the 2026 ro-pax text tries to enforce with section-matched detection and video, and it is what a car carrier has to specify for itself until 2032.

Sources

• 1. IMO Resolution MSC.550(108), adopted 23 May 2024, in force 1 January 2026 — SOLAS II-2/20 as amended: 2.1.3 (retroactive application to passenger ships built before 2026); 4.1 application text (4.1.1–4.1.4 passenger ships constructed on or after 1 January 2026; 4.1.5 cargo ships constructed on or after 1 January 2026; earlier cargo ships comply with the previously applicable 4.1); 4.1.6, 4.4 and 6.2.3 (existing passenger ships, first survey on or after 1 January 2028); 5 and 6.2 (openings, safety distances, weather-deck monitors, 125% drainage). Read from the resolution text.
• 2. IUMI — "Risk mitigation for the safe ocean and short-sea carriage of electric vehicles", September 2025 revision, read in full: EV fire frequency estimated lower than conventional vehicles over the same distance; total heat release shows a minor difference, "EV fires are not more intense than ICEV fires", peak heat release may be higher depending on battery type, SoC affects growth and peak; approx. 20% of fire load from the energy source and 80% from plastics and interior regardless of propulsion; LASH FIRE full-scale tests show a drencher has the same impact on the fire whether ICEV or EV, but cannot stop thermal runaway; no extinguishing media can interrupt the chain reaction; re-ignition risk higher for longer than ICEVs; the SOLAS and FSS Code amendments "will mainly apply to new passenger ships"; no international requirements for SoC agreed; "time between detection and confirmation/verification must be reduced to the shortest possible period".
• 3. IUMI — "Fire protection on top of the agenda at SSE 11", newsletter March 2025: MSC 105 tasked SSE with the new-energy-vehicle output over four sessions beginning in 2024 and concluding in 2027; the Fire Protection Working Group's five-part action plan (review of reports, studies, technologies and casualty reports; hazards of NEVs compared with ICEVs; goal-based approach; regulatory gaps; placeholders for future amendments); correspondence group to SSE 12.
• 4. IMO — Sub-Committee on Ship Systems and Equipment, 11th session (24–28 February 2025), meeting summary: Fire Protection Correspondence Group established on the new-energy-vehicle output, reporting to SSE 12.
• 5. DNV — "IMO Sub-Committee on Ship Systems and Equipment (SSE 12)", March 2026; Riviera Maritime Media coverage of SSE 12 (9–12 March 2026): revised action plan; priority to interim guidelines on fire safety measures for PCTCs and on video monitoring and detection systems before SOLAS amendments; correspondence group to SSE 13 (March 2027); entry into force 1 January 2032 at the earliest.
• 6. UN 3556 / IMDG Code special provision 961 and the EMSA 20–50% SoC guidance are covered, with their sources, by the linked posts EVs Got a New UN Number — Does It Help? and The Argument Over State-of-Charge at Loading; no new primary was opened for them this run.