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How To Plan Electrical Works For UPS Installations

An uninterruptible power supply will provide years of reliable service if it is installed correctly and maintained. Whether your server room or datacentre has single or three phase UPS systems, similar planning is required to ensure that the UPS is installed correctly and powers all the loads it is expected to.

Transporting UPS Systems to Site

UPS systems even without their batteries are heavy and sometimes bulky items to transport. The logistics side of a UPS installations should be covered during a UPS site survey and run from any permits required outside the building, along the delivery route to the final installation location. Sometimes it is the obvious that can catch out an installation project such as a small step or narrow or low door-frame. If there is a raised floor, the weight of the entire UPS system may require a plinth on the concrete base to be installed upon. UPS systems also contain sensitive electronics and suitable vehicles must be used to ensure transportation vehicles have suitable suspensions. Without adequate planning and assessment a UPS installation deadline can be missed.

The final place of location whether it’s a floor standing UPS system or a rack mounted one, must ensure adequate air flow and access for maintenance. The UPS site survey should have included an assessment on temperature and humidity requirements and the impact the uninterruptible power supply will have on local cooling systems.

Connecting IT Loads to The Critical Power Path

The critical power path within a UPS installation runs from the loads connected to the power distribution units (PDUs) to the UPS that power the PDUs and to the UPS electrical supplies and potentially the building incomer.

Planning how to power the loads from the uninterruptible power supply is an important exercise. Smaller single-phase UPS use rear panel IEC type connectors to which PDUs, or a UPS maintenance bypass switch can be connected. If a UPS maintenance bypass switch is installed the PDU and load connection may be via a sub-distribution board. Larger single-phase UPS from 5kVA upwards tend to be hardwired as do three phase UPS. Three phase UPS systems typically use rear panel hardwired connections with an option for a top-entry cabinet for use with an overhead cable containment system.

As well as the AC cable connections and ensuring there is suitably rated cable and enough room for the cable bend radius, external battery packs will require DC cable installation. Smaller UPS systems in a server room or datacentre tend to be installed in-rack or in-row with larger systems installed on the periphery or within their own UPS and battery rooms.

Electrical Installations Work

Smaller single-phase UPS may use ‘plug and play’ connections meaning that they can be easily installed by a local user or technician. Hardwired UPS and those requiring additional electrical works (e.g. cabling, circuit breakers and distribution panels) require installation by a suitably qualified electrical contractor or electrician.

This is because in the UK electrical installations must comply with national regulations and guidelines including: BS7671 18th edition IEE wiring regulations. This is because in the UK electrical installations must comply with national regulations and guidelines including: BS7671 18th edition IEE wiring regulations. For more information on NICEIC and BS7671 please see:

A suitable electrical contractor should be NICEIC or ECA certified and hold the necessary health & safety accreditations or standards including ISO 18001 or its replacement ISO 45001 or SAFEContractor. Without qualified personnel the installation may be ‘illegal’ and pose a safety risk in terms of electric shock, poor earthing and even a potential fire risk. All of which can invalidate building insurance should a problem occur, and it be traced back to poor UPS installation.

Electrical installation is therefore specialist work and a suitable qualified NICEIC or ECA electrical contractor will be able to install the UPS system. The UPS installation may require additional distribution panels and uprated circuit breakers. Larger three phase UPS systems with a maintenance bypass may require a Castel interlock arrangement and connection to load distribution panels. Even the addition of a fused-spur for single phase UPS requires qualified personnel. The site may also require security vetted personal or specific health & safety training. UPS electrical installation is a different type of work to UPS commissioning which is a separate procedure that can only follow once the electrical works have been completed and signed-off.

UPS manufacturers often require their systems to be commissioned by certified UPS engineers. There are several reasons for this approach. UPS manufacturers may not validate the UPS warranty of a system not installed by certified engineers. The UPS commissioning engineer will have undergone training on how to inspect, test and commission the uninterruptible power supply. This certification will be range specific. UPS manufacturers typically offer several UPS ranges and though it can be relatively straight forward to commission a UPS with the right commissioning software and procedures, installation routines can be range specific.

Once the UPS is safely commissioned, the UPS commissioning engineer will hand over a commissioning sheet which will require the readings and test results, UPS configuration and installation specific information including model and serial numbers, battery and UPS maintenance bypass switch arrangements. This sheet should then form part of the UPS maintenance log which should always be nearby to the UPS installation and to register the installation with the UPS supplier and manufacturer. Registration assists the UPS supplier and manufacturer with traceability for any quality issues, firmware upgrades and ensures that the site has access to technical support and services during its warranty period. Some manufacturers insist on registration within 90 days of commissioning.


Within some server rooms and datacentre environments it is easy to miss connecting a critical piece of the IT network to a UPS system. Only during a power outage is the omission identified. Planning and preparation are therefore important tasks for any size of UPS installation and this work must be managed by suitably qualified project managers who can interface with suitably trained UPS commissioning engineers and certified electrical contractors. Once a UPS system has been installed and commissioned correctly it should be placed under a maintenance contract to provide the required level of emergency call out and provide an annual preventative maintenance visit.

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