Vertiv VA4N21A0 Monitored Rack Transfer Switch PDU, 20A 120V

Overview

The Vertiv VA4N21A0 is a 1U horizontal rack-mount monitored transfer switch PDU rated at 20A/120V (1.9kW) with ten NEMA 5-20R outlets — purpose-built for data center and server room environments where dual-input power redundancy and outlet-level visibility are non-negotiable. The VA4N21A0 handles automatic transfer between two feed circuits so your rack load survives an upstream failure without a manual switchover, while the monitored layer gives your ops team real-time consumption data per outlet and full SNMP integration with your existing management stack.

Unlike basic PDUs that simply distribute power, the VA4N21A0 combines transfer switching with granular monitoring — you get load metering, environmental alerting, and protocol-rich management in a single 1U footprint. For edge deployments, co-lo cages, or dense server rows where every rack unit is contested, consolidating redundancy and monitoring into one device is a meaningful operational win.

Key Features

• Automatic Transfer Switching at 20A / 1.9kW: The unit accepts two separate power inputs (100–120V) and automatically transfers the connected load to the live feed if one source fails — no downtime, no manual intervention. At 1.9kW capacity, it comfortably handles a standard server rack load without requiring a larger 208V infrastructure.
• Ten NEMA 5-20R Outlets: Ten 20A receptacles provide enough drops for a full 1U-to-2U server row. NEMA 5-20R is the standard for 20A single-phase equipment in North American data centers, so compatibility with existing PDU whips and server power supplies is straightforward — no adapters required.
• Monitored Unit-Level Metering: Real-time power monitoring at the unit level lets you track aggregate load against the 20A circuit rating. You'll know before you trip a breaker, and you'll have the consumption history to right-size refresh cycles and capacity planning.
• Enterprise Protocol Stack — SNMP v3, RADIUS, TACACS+, LDAP: The VA4N21A0 speaks every protocol your enterprise security team will ask for. SNMP v1/v2c/v3 for NMS polling and trap delivery, RADIUS and TACACS+ for centralized authentication and accounting, LDAP for directory-integrated access control. SSH and HTTPS enforce encrypted management channels; HTTP can be disabled. This is the protocol depth you need when IT Security reviews the rack PDU purchase.
• IPv4 and IPv6 Dual-Stack Networking: Dual-stack support means the unit integrates cleanly into modern network environments without requiring NAT workarounds or separate management VLANs. NTP keeps timestamps consistent for syslog correlation across your SIEM.
• DHCP / Static IP and Syslog / SMTP Alerting: DHCP simplifies initial commissioning; assign a static IP before production. Syslog and SMTP alerting push events to your log aggregator or on-call inbox — you don't have to poll the device to know about a transfer event or overload condition.
• 1U Horizontal, 17-Inch Form Factor: At 1.72 in tall × 17 in wide × 18 in deep, the VA4N21A0 mounts in a standard 19-inch rack rail set with 1U of space consumed. The 18-inch depth is within the envelope of most 24-inch deep server cabinets with room for cable management behind the outlet face.
• 60°C / 140°F Rated Operating Temperature: Data center hot-aisle temperatures regularly approach 45–50°C at the rack. The 60°C upper bound gives meaningful thermal headroom for high-density rows with poor airflow management — or for edge deployments in non-conditioned spaces.
• UL Listed 62368, FCC Part 15, RoHS Compliant: UL 62368 is the current safety standard for audio/video and IT equipment — required by most enterprise procurement policies and co-location facility agreements. FCC Part 15 Class A compliance confirms the unit won't interfere with sensitive lab or broadcast environments. RoHS compliance covers disposal and sustainability reporting requirements.

Integration and Compatibility

The VA4N21A0 integrates into any SNMP-capable NMS or DCIM platform via v1/v2c/v3 MIBs. For environments running rack power distribution under centralized DCIM, the device's Syslog output can feed directly into log aggregators for event correlation. RADIUS and TACACS+ integration allows role-based management access without local account proliferation — consistent with enterprise privileged access management (PAM) policies. The RSTP support on the network interface prevents spanning-tree loops if the management port lands on a managed switch fabric.

Pair this unit with a compatible UPS and battery backup on each feed for full N+1 redundancy. The unit's dual-input design assumes two physically independent power paths — a single UPS feeding both inputs defeats the purpose. Review your rack cabinet cable management plan before installation: ten 20A outlet pigtails in a 1U device generate meaningful cord density behind the unit.

For broader Vertiv power infrastructure context — UPS, power distribution, and thermal management — the VA4N21A0 sits at the distribution edge of Vertiv's rack power lineup. It is not a surge-only strip; it is a transfer switching device and should be treated as critical infrastructure in your rack BOM.

Frequently Asked Questions

Q: What is the maximum load capacity of the VA4N21A0?

A: The VA4N21A0 is rated at 20A / 1.9kW at 120V (100–120V input range). Do not load the circuit above 16A continuous (80% of the 20A rating) per NEC best practices to avoid nuisance trips.

Q: How many outlets does the VA4N21A0 provide, and what receptacle type?

A: It provides 10 NEMA 5-20R outlets, which accept standard 20A single-phase plugs common to North American server and networking equipment.

Q: Does the VA4N21A0 support SNMP v3 and encrypted management?

A: Yes. The unit supports SNMP v1, v2c, and v3, along with SSH and HTTPS for encrypted CLI and web-based management. HTTP is also available but can be disabled for security-hardened deployments.

Q: Can the VA4N21A0 authenticate management users against a RADIUS or TACACS+ server?

A: Yes. The unit's protocol stack includes both RADIUS and TACACS+ for centralized authentication and LDAP for directory-based access — making it compatible with enterprise PAM and identity governance requirements.

Q: What rack space does the VA4N21A0 require?

A: The unit occupies 1U of horizontal rack space (1.72 in tall × 17 in wide × 18 in deep) and mounts in a standard 19-inch rail set.

Q: What safety certifications does the VA4N21A0 carry?

A: The VA4N21A0 is UL Listed to 62368 (the current IT/AV equipment safety standard), FCC Part 15 Class A compliant, and RoHS compliant.