A Checklist for Planning a 10–40kVA 3Phase UPS Installation

A 10–40kVA three-phase UPS with 10 to 30 minutes of runtime is a common specification for mid-sized server rooms and smaller data centres. This size of UPS is big enough to protect a full rack row or a modest server environment, but small enough to remain a relatively contained project. But “contained” does not mean simple. Getting a project like this right means planning well beyond the final UPS handover.

UPS Sizing and Resilience Levels

First, calculate your actual connected load requirements. This may be measured in kVA and/or kW. You can determine load from IT hardware brochures and manuals, from actual measurements by a suitably qualified electrician at the distribution board level, or from existing PDUs with branch or output-level monitoring. Then take the total and add at least 20% for headroom or more for future growth.

The next step is to decide the level of resilience the UPS installation must achieve. This could be a single unit (N) or two (or more) UPS connected in a parallel/redundant configuration. For most server rooms, N is sufficient, giving a Tier-1 approach to uptime.

Leading manufacturers (including APC, Eaton, Legrand, Schneider Tecnoware, and Vertiv) offer several models in this power range: 10-40kVA UPS range. Getting the sizing right matters; our UPS sizing guide walks through the calculation in detail. From there, you can browse 3phase UPS systems and filter by 10kVA, 20kVA, 30kVA, or 40kVA depending on where your load lands.

If this first step is a hurdle, consider asking our Projects Team for a site survey or Teams call.

For more information on Tier-levels see: https://uptimeinstitute.com/tiers

Electrical Works

A 3phase UPS will require a hardwired electrical installation. Electrical works to plan for include:

• Incomer Capacity Checks: confirming the available three-phase supply can support the UPS system and its charging current, including upstream breaker sizes and distribution boards or switchgear.
• Dedicated Output Circuits: separate protected circuits from the UPS output to sub-distribution, sized correctly for the load and with the right connections; 16A or 32A commando plugs to connect to PDUs within the server racks.
• Cabling Routes: planned early, particularly in retrofit environments where existing containment may not have capacity.
• Earthing and Bonding: verified to the relevant BS 7671 18th edition requirements by a suitably qualified electrician or electrical contractor.
• UPS Maintenance: consider installing an external UPS bypass to allow the UPS to be maintained without disrupting the connected load(s).
• Generator Interface: if a standby power generator is installed, there may be additional installation requirements, including signal interfaces and AMF (automatic mains failure) panels.

This is specialist work, and it is worth having it project-managed alongside the UPS install rather than handled separately; our Projects Team can manage all your electrical installation service requirements.

Onsite Testing and Commissioning

Part of the electrical installation is testing and commissioning before the UPS is connected to the final load. The UPS and its electrical and battery connections are tested using calibrated meters, and results recorded on a Job or Works Report.

Load bank testing can verify UPS performance by simulating the load. Most load banks are resistive, and using a load bank requires additional planning and co-ordination. However, some UPS units can also simulate a load as part of their electrical characteristics. A battery discharge test can confirm actual runtime matches the required specification.

External Maintenance Bypass

For a UPS in this capacity range, an external (wraparound) maintenance bypass is worth including from day one rather than retrofitting later. It allows the UPS to be taken fully offline for servicing, battery replacement, or future upgrades without interrupting power to connected equipment — something that becomes increasingly important as the installation grows into a genuinely critical system. Our range of maintenance bypass switches covers manual and automatic options to suit different levels of resilience.

Remote Monitoring

Without remote monitoring, your UPS could be in an alarm mode, and you may not even know it. Alarms can happen for all sorts of reasons, from minor to major, and should be investigated.

The most common form of remote monitoring is to add an IP/SNMP card to your UPS system, either as a plug-in card or an external product. The card connects the UPS to the IP network for remote monitoring via browser (HTTP/HTTPS) or UPS monitoring software. The latter will usually provide an operational schematic, show alarm log,s and display key information such as operating state and key UPS measurements including load %, battery charge %, input and output voltage and frequency, and estimated battery runtime.

For sites without staff onsite around the clock, pairing the SNMP card with monitoring software that can alert by email or SMS closes the gap between a fault occurring and someone knowing about it.

Temperature and Humidity Controls

The heat generated by a UPS depends on its load and energy efficiency. The UPS heat load should be considered within the wider context of the overall room ambient control system. UPS-generated heat and batteries, particularly valve-regulated lead-acid (VRLA) batteries, are sensitive to heat. For every 1°C above 30°C, the design life of a VRLA battery halves.

Cooling for the UPS and battery cabinets needs to be planned as part of the same project as the wider room cooling, not treated as an afterthought. Our server room cooling systems range covers options suitable for rooms of this scale.

Ongoing Maintenance Contracts and Emergency Call Out

Single and 3-phase UPS systems should be covered by a UPS maintenance contract or service plan, with emergency call-out facilities. The UPS will require scheduled preventative maintenance, at least once a year, that will provide periodic inspection, battery testing, capacitor checks, and firmware updates.

Batteries, in particular, are a consumable item; VRLA batteries typically need replacing every 3–5 or 7-8 years depending on the design life installed, regardless of how healthy the UPS itself appears. Fans are also consumables. Our on-site UPS Service team provides maintenance contracts with 24/7 support for exactly this kind of installation.

Environmental Monitoring Systems

A 3phase UPS may be installed with a volt-free contact (VFC) dry-contacts interface card or an SNMP monitoring card. Adding a smart environmental monitoring device to the installation can add another level of resilience and reporting. The monitoring device can log dry-contact signals and/or SNMP information for the UPS system and use it to trigger email alerts and SMS text messages to an escalation list. The information can also be shown on a dashboard, accessible via a browser. The monitoring device provides 24/7 recording of the UPS state, with notifications sent to predefined lists should a change-of-state cross an alarm threshold. Additional information that can be monitored includes room temperature and humidity levels, water leakage detection, server rack and room-level entry, and information from third-party devices via signal contacts or ModBus.

Summary

A 10–40kVA three-phase UPS system project touches electrical infrastructure, cooling, monitoring, and long-term maintenance planning; treating it as a single joined-up project, rather than a UPS purchase with product and service add-ons bolted on afterwards, delivers a more resilient installation that will provide years of power protection.

If you are planning a 3phase UPS installation, please contact our Projects team for an initial discussion and overview. We bring years of experience to your project, saving you time and money and delivering a resilient, uninterruptible power installation.