Core Differences between UL 2140 and UL 2755 (Pre-fabricated Modular Data Centers/Power Modules, NEC Standard)
Both are UL investigation outlines (Outline of Investigation, not a traditional single-product standard), targeting North American pre-integrated data center projects, specifically for NEC Article 646 modular data centers. The assessment objects of the two are completely different, and many projects involving liquid cooling for artificial intelligence computing and container data centers are prone to confusion.
UL 2140
Full name: Prefabricated Power Distribution Assemblies (Pre-fabricated Power Distribution Integrated Device / Power Skid)
Evaluation object: Only for the [Pre-fabricated Power Distribution System], excluding IT server cabinets, cooling systems, and the overall enclosure of the data center.
Product scope: Factory-prepared integrated complete sets of power distribution skids, such as: high-voltage cabinets, transformers, UPS, PDUs, busbars, energy storage, circuit breakers integrated in the same base/container as the power assembly (Power Skid).
Evaluation focus: Power distribution circuits, protection coordination, grounding, short-circuit tolerance, electrical isolation, internal wiring, transportation vibration, protection.
One sentence: Only test "power supply module", the power skid is certified separately.
Typical scenario: Independently manufactured pre-fabricated power modules, used as the power supply system of the data center, can be independently purchased and transported.
Release time: Newly launched in 2026 (Schneider obtained the world‘s first UL2140 certificate)
UL 2755
Full name: Prefabricated Modular Data Center Systems (Complete Modular Data Center System, a complete data center enclosure)
Evaluation object: The complete modular data center MDC system, which is a complete data center.
Includes all subsystems: Power supply + IT server cabinets + cooling (cold plate/liquid cooling) + fire protection + monitoring + data center enclosure structure, passageways, access control, emergency evacuation.
Evaluation focus:
1. Electrical safety of the entire system (refer to NEC 646)
2. Safety of the cooling system, liquid cooling pipelines
3. Building structure, lifting and transportation strength
4. Personnel maintenance safety, evacuation channels, fire detection and extinguishing linkage
5. Integration and matching of all internal subsystems (IT equipment, power supply, fire protection)
One sentence: The entire container/module data center as a single product system certification.
Typical scenario: It is a complete data center enclosure when it leaves the factory, and can be connected to water and electricity at the site and go online.
Comparison table
Key points for project selection (US standard for intelligent computing/liquid cooling projects focus on)
1. If the project is a standalone prefabricated power unit (transformer + UPS + power distribution integrated box, without server cabinets) → UL 2140
2. If the product is a container-type complete system data center (power supply + liquid cooling + IT cabinets all installed in the same compartment) → UL 2755
3. Combination scheme: The power distribution unit in the complete MDC system (UL 2755) can be tested separately as UL 2140, UL 2755 will recognize the power electronic system with UL 2140 inside, reducing the testing workload of the entire system.
4. Note: Both are not component standards, they belong to system-level certification, the scope of review is much larger than UL 1558 (switch cabinets), UL 1561 (transformers) such as single equipment standards; Components (transformers, circuit breakers) still need their own independent UL certificates, the overall risk after integration is evaluated by the system standard.
Both are UL investigation outlines (Outline of Investigation, not a traditional single-product standard), targeting North American pre-integrated data center projects, specifically for NEC Article 646 modular data centers. The assessment objects of the two are completely different, and many projects involving liquid cooling for artificial intelligence computing and container data centers are prone to confusion.
Full name: Prefabricated Power Distribution Assemblies (Pre-fabricated Power Distribution Integrated Device / Power Skid)
Evaluation object: Only for the [Pre-fabricated Power Distribution System], excluding IT server cabinets, cooling systems, and the overall enclosure of the data center.
Product scope: Factory-prepared integrated complete sets of power distribution skids, such as: high-voltage cabinets, transformers, UPS, PDUs, busbars, energy storage, circuit breakers integrated in the same base/container as the power assembly (Power Skid).
Evaluation focus: Power distribution circuits, protection coordination, grounding, short-circuit tolerance, electrical isolation, internal wiring, transportation vibration, protection.
One sentence: Only test "power supply module", the power skid is certified separately.
Typical scenario: Independently manufactured pre-fabricated power modules, used as the power supply system of the data center, can be independently purchased and transported.
Release time: Newly launched in 2026 (Schneider obtained the world‘s first UL2140 certificate)
UL 2755
Full name: Prefabricated Modular Data Center Systems (Complete Modular Data Center System, a complete data center enclosure)
Evaluation object: The complete modular data center MDC system, which is a complete data center.
Includes all subsystems: Power supply + IT server cabinets + cooling (cold plate/liquid cooling) + fire protection + monitoring + data center enclosure structure, passageways, access control, emergency evacuation.
Evaluation focus:
1. Electrical safety of the entire system (refer to NEC 646)
2. Safety of the cooling system, liquid cooling pipelines
3. Building structure, lifting and transportation strength
4. Personnel maintenance safety, evacuation channels, fire detection and extinguishing linkage
5. Integration and matching of all internal subsystems (IT equipment, power supply, fire protection)
One sentence: The entire container/module data center as a single product system certification.
Typical scenario: It is a complete data center enclosure when it leaves the factory, and can be connected to water and electricity at the site and go online.
Comparison table
Key points for project selection (US standard for intelligent computing/liquid cooling projects focus on)
1. If the project is a standalone prefabricated power unit (transformer + UPS + power distribution integrated box, without server cabinets) → UL 2140
2. If the product is a container-type complete system data center (power supply + liquid cooling + IT cabinets all installed in the same compartment) → UL 2755
3. Combination scheme: The power distribution unit in the complete MDC system (UL 2755) can be tested separately as UL 2140, UL 2755 will recognize the power electronic system with UL 2140 inside, reducing the testing workload of the entire system.
4. Note: Both are not component standards, they belong to system-level certification, the scope of review is much larger than UL 1558 (switch cabinets), UL 1561 (transformers) such as single equipment standards; Components (transformers, circuit breakers) still need their own independent UL certificates, the overall risk after integration is evaluated by the system standard.