Vertiv NMBHW81 20kVA Manual Bypass Cabinet for Nfinity UPS
Overview
The Vertiv NMBHW81 is a 20kVA wall-mountable bypass cabinet engineered specifically for the Vertiv Liebert Nfinity UPS line. Rated at 125 amps with multi-voltage output support (120/120/208/240V), it gives data center and facilities engineers a clean path to perform UPS maintenance or swap-out without dropping a single watt to the protected load. If you run Nfinity UPS systems and need a code-compliant, hardware-native bypass solution, the NMBHW81 is the purpose-built answer — not a generic third-party workaround.
Key Features
- 20kVA / 125A Capacity: Sized to carry the full rated load of a Liebert Nfinity UPS system without derating. A 125A output circuit breaker provides overcurrent protection on the bypass path — the load stays protected even when the UPS is out of the circuit.
- Manual Bypass Switch: Allows controlled transfer of the load directly to utility power, isolating the UPS for maintenance, firmware updates, or hardware replacement. No specialized tools required for the transfer sequence, reducing mean time to service.
- UPS Input Disconnect: Built-in disconnect lets you fully de-energize the UPS input without touching upstream distribution. This is the feature that makes safe hot-swap service practical — you don't have to trace back to the panel breaker during a live maintenance window.
- Multi-Voltage Output — 120/120/208/240V: Covers the four most common North American data center and facility voltages in a single unit. Whether your UPS installation feeds 120V edge compute gear or 208V server racks, the NMBHW81 accommodates without additional transformers.
- 50Hz / 60Hz Frequency Support: Dual-frequency compatibility means this cabinet works in both North American 60Hz facilities and international 50Hz environments — useful for multi-site organizations standardizing on a single bypass SKU.
- Wall-Mountable Form Factor: Ships at 52 lbs and mounts directly to the wall, keeping floor space clear. For power protection installs in tight IDF closets or wall-adjacent UPS deployments, this matters more than most spec sheets acknowledge.
- Manufactured in Mexico — North American Supply Chain: Country of origin is Mexico, which keeps lead times predictable for North American deployments and supports TAA-adjacent procurement workflows where country-of-origin documentation is required.
Integration and Compatibility
The NMBHW81 is verified compatible with the Vertiv Liebert Nfinity UPS family. If you are deploying or maintaining a Vertiv Liebert Nfinity installation and need a bypass cabinet, this is the OEM-matched component — wiring interfaces, control logic, and mechanical mounting are designed to pair with Nfinity chassis. Do not substitute a generic bypass switch; mismatched bypass cabinets on modular UPS systems can create neutral-bonding and ground-fault conditions that void equipment warranties and create NEC compliance issues.
Frequently Asked Questions
Q: What UPS systems is the NMBHW81 compatible with?
A: The NMBHW81 is designed and verified for use with the Vertiv Liebert Nfinity UPS product family. It is not a universal bypass cabinet.
Q: What voltages does the NMBHW81 support?
A: The NMBHW81 supports 120V, 208V, and 240V output (listed as 120/120/208/240V), covering the primary North American data center and facility voltage configurations.
Q: Does the NMBHW81 support 50Hz operation?
A: Yes. The cabinet supports both 50Hz and 60Hz, making it usable in international facilities as well as standard North American 60Hz installations.
Q: Can the NMBHW81 be wall-mounted?
A: Yes. The NMBHW81 is wall-mountable, with a shipping weight of 52 lbs. Verify wall structure and fastener ratings before installation.
Q: What circuit protection does the NMBHW81 provide on the bypass path?
A: A 125A output circuit breaker is integrated into the bypass path, providing overcurrent protection to the load even when the UPS is bypassed.
The NMBHW81 is the component that makes Liebert Nfinity UPS maintenance actually safe in a production environment. That 125A integrated output circuit breaker on the bypass path is what separates this from a simple transfer switch — your downstream load stays protected to 125A even while the UPS is completely isolated, which matters when the gear on the other side of that cabinet is live infrastructure you cannot afford to drop.
Technical Highlights:
- 125A Output Circuit Breaker: Provides continuous overcurrent protection on the bypass path — not just a switch, but a protected transfer. Load protection does not lapse during UPS maintenance windows.
- Multi-Voltage 120/120/208/240V: A single bypass cabinet covers the four most common North American voltage configurations, eliminating the need for separate bypass hardware per voltage tier in mixed-voltage facilities.
- UPS Input Disconnect: The built-in disconnect is the functional core of safe hot-swap service — it lets technicians de-energize the UPS without tracing back to upstream panel breakers during a live maintenance event.
Deployment Considerations:
- This cabinet is Nfinity-specific. Wiring interface and control logic are matched to that platform — do not attempt to pair with a different UPS family without consulting Vertiv engineering.
- At 52 lbs wall-mounted, confirm your wall structure and anchor hardware can carry the load before commissioning. In masonry or metal-stud environments, use appropriate anchors rated for the combined static and dynamic load.
The NMBHW81 is the right spec for facilities teams managing Liebert Nfinity deployments in edge data centers, IDF closets, or distributed enterprise sites where floor space is constrained and UPS serviceability needs to be planned — not improvised during an outage.
