Vertiv Rpdu Rack Transfer Switch Monitored Unit Level 16A or 20A 120V or 208V or 230 - VA4U21A0

Vertiv VA4U21A0 Monitored Rack PDU — 1U Horizontal, 20A, 12-Outlet

Overview

The Vertiv VA4U21A0 is a 1U horizontal rack-mount monitored power distribution unit designed for data center aisles, server rooms, and dense equipment racks where real-time power visibility matters as much as outlet count. It accepts a C20 input plug and distributes up to 3,600W across 12 outlets (a mix of C13 and C19 receptacles), handling loads from 100V to 240V single-phase — which means the same unit deploys in North American 120V environments, 208V two-post racks, and international 230V installations without swapping hardware. For engineers provisioning rack power distribution across mixed voltage environments, that flexibility directly reduces SKU proliferation in your spares inventory.

The VA4U21A0 ships with dual RJ-45 Ethernet ports, one serial port, and one USB port, giving it enough connectivity to integrate into virtually any out-of-band management topology. Monitoring covers current, voltage, and power at the unit level — the data you need to spot an overloaded circuit before a breaker trips, not after. The supported protocol stack is enterprise-grade: SNMP v1/v2c/v3, HTTPS, SSH, LDAP, RADIUS, TACACS+, Modbus TCP/IP, Syslog, and more. That list covers the major DCIM platforms, network management stacks, and security audit requirements you're likely to face in a mid-size to enterprise deployment.

Key Features

• 3,600W Maximum Load at 20A: The C20 input handles up to 20A at 230V, delivering a 3,600W ceiling — enough headroom for a fully loaded 1U rack shelf of 1U servers or a mix of network switches and storage, without nuisance tripping under transient spikes.
• 12-Outlet Mix (C13 + C19): C13 receptacles cover standard 1U and 2U servers; C19 handles higher-draw devices like high-density switches, storage arrays, or UPS bypass paths. Having both outlet types on a single PDU eliminates the need for adapter cords that add points of failure and resistance.
• Dual RJ-45 Ethernet Ports: Two network ports support daisy-chain or dual-homed configurations — useful when you want the PDU reachable on both a management VLAN and a primary LAN, or when stringing multiple PDUs without burning switch ports. Pair these with a managed PoE switch for consolidated out-of-band management.
• Unit-Level Monitoring (Current, Voltage, Power): Real-time current draw, voltage, and power readings let you baseline rack load, catch creeping capacity problems, and satisfy power audit requirements without installing additional metering hardware. This is the spec that separates a monitored PDU from a basic strip — and it pays off fastest in dense racks where oversubscription risk is highest.
• SNMP v1/v2c/v3 + Modbus TCP/IP: SNMP v3 adds authentication and encryption absent in earlier versions — relevant if your security team audits management-plane protocols. Modbus TCP/IP extends integration to building management systems (BMS) and SCADA environments, which is uncommon at this form factor and price tier.
• Enterprise AAA: LDAP, RADIUS, TACACS+: All three AAA protocols are supported, so the PDU drops into existing identity infrastructure rather than requiring local credentials managed out-of-band. In environments with SOC2 or ISO 27001 requirements, this keeps the PDU inside your access-control perimeter.
• Wide Input Voltage: 100–240V: Single-phase operation across the full global voltage range means the VA4U21A0 works off a standard 20A branch circuit in a US data center or a 230V IEC feed in a European colo — same firmware, same management interface, same spare on the shelf.
• Certifications — UL/c-UL 62368-1, CE, UKCA, RCM, IEC 62368-1: UL 62368-1 listing satisfies the safety compliance requirement for most North American enterprise procurement. CE and UKCA cover EU and UK deployments. RCM covers Australia/New Zealand. One SKU clears compliance across four major regulatory zones.
• Protocol Suite — IPv6, NTP, RSTP, Syslog, SMTP: IPv6 support future-proofs management plane addressing. RSTP enables fault-tolerant Ethernet topologies. SMTP delivers alert emails directly without a relay agent. Syslog integration routes PDU events into your existing log aggregation stack.

Integration and Compatibility

The VA4U21A0's protocol breadth — SNMP v3, Modbus TCP/IP, LDAP, RADIUS, TACACS+ — gives it a wide integration surface. SNMP traps and MIBs slot into standard DCIM tools and NMS platforms. Modbus TCP/IP opens a path to BMS integration that most IT-class PDUs do not offer. The dual Ethernet ports accommodate both IP-connected management and daisy-chain topologies, reducing cabling runs in long-aisle deployments. The 1U horizontal form factor fits standard 19-inch racks; horizontal mounting keeps the unit accessible at any RU position without requiring a zero-U side bracket. Review your rack PDU selection guide to confirm the C20 inlet matches your branch circuit protection and that the C13/C19 outlet mix aligns with your connected device cord types before ordering.

Frequently Asked Questions

Q: What is the maximum current and wattage the VA4U21A0 supports?

A: The VA4U21A0 supports a maximum of 20A input current with a maximum power output of 3,600W (3.6kW). It uses a C20 coupler for input and distributes across 12 outlets.

Q: What outlet types does the VA4U21A0 provide?

A: It provides a mix of C13 and C19 IEC outlet types. C13 outlets are standard for most 1U/2U servers; C19 outlets handle higher-draw devices such as high-density switches and storage arrays.

Q: Does the VA4U21A0 support SNMP v3?

A: Yes. The VA4U21A0 supports SNMP v1, v2c, and v3. SNMP v3 includes authentication and encryption, satisfying management-plane security requirements in enterprise and compliance-sensitive environments.

Q: What voltage ranges does the VA4U21A0 support?

A: The unit supports a nominal input voltage range of 100–240V single-phase, covering standard 120V North American circuits, 208V data center feeds, and 230V international installations with the same hardware.

Q: What certifications does the VA4U21A0 carry?

A: The VA4U21A0 is UL and c-UL Listed to 62368-1, CE Marked, UKCA Marked, RCM Marked (EMC), and complies with IEC 62368-1. This covers safety compliance for North American, EU, UK, and Australian/New Zealand deployments.

Q: Does the VA4U21A0 support integration with building management systems?

A: Yes. The unit supports Modbus TCP/IP, which is the protocol commonly used by building management systems (BMS) and SCADA platforms. This is unusual for a 1U IT-class PDU and relevant in mixed IT/facilities management environments.

Marty Allison

The VA4U21A0 is the unit I reach for when a client needs visibility into rack power consumption without stepping up to outlet-level switched PDUs — the unit-level monitoring (current, voltage, and real power) covers the majority of capacity-planning and audit use cases at a lower cost point, and the 3,600W / 20A ceiling handles everything short of a GPU-dense AI compute shelf.

Technical Highlights:

• Dual RJ-45 Ethernet: Two network ports let you place the PDU on a dedicated management VLAN while keeping a secondary path available — no management dead-end if a switch port goes down, and no extra switch ports burned when daisy-chaining multiple PDUs in a long aisle.
• SNMP v3 + LDAP/RADIUS/TACACS+: The combination of encrypted SNMP and enterprise AAA integration means this PDU satisfies the management-plane requirements most enterprise security teams impose — no local credential silos, no plaintext SNMP community strings on the wire.
• 100–240V Single-Phase Input: The wide voltage acceptance range means procurement can stock one SKU for domestic 120V/208V deployments and international 230V colo space. That matters when you're managing spares across multiple facilities in different countries.

Deployment Considerations:

• The C20 inlet requires a C19-to-C20 whip or a dedicated C20-terminated branch circuit — confirm your PDU panel or in-row UPS output matches before racking the unit. A C19 outlet on the upstream UPS is the typical pairing.
• Monitoring is unit-level only — current, voltage, and power are reported for the entire PDU, not per-outlet. If you need per-outlet metering or switched outlet control (for remote power cycling), you'll need to step up to a higher-tier Vertiv PDU model in the same family.

This unit fits best in server rooms and colo cages where the primary requirement is power visibility and enterprise protocol compliance — think a mid-size enterprise with DCIM tooling that polls SNMP v3 and a security team that requires AAA-authenticated device access. It is not the right pick for environments needing outlet-level switching or per-outlet current metering.