Electrical Solutions for Healthcare

Why hospital loads are unlike any other building

A hospital runs a mixed and unusually demanding electrical load. Theatres, imaging suites, intensive care, laboratories, sterilisation plant, laundry, medical gas compressors, lifts and ward lighting all draw from the same intake, and several of them are sensitive to voltage dips that the rest of the building would never notice. Large motors and imaging equipment also present short, heavy starting currents that have to be accounted for when the incoming supply and the protection settings are chosen.

The other difference is that load in a hospital is graded by consequence rather than by size. A small circuit feeding a ventilator matters more than a large one feeding a laundry, so the distribution design starts from a schedule of which circuits may be interrupted, which may be interrupted briefly, and which may not be interrupted at all.

Separating essential from non-essential supplies

That grading is realised physically in the switchboards. Essential circuits are gathered onto their own sub-main and final distribution boards and fed through an automatic transfer switch panel, so the standby generator picks them up when the KPLC supply fails, while non-essential boards are left on the utility alone. A manual transfer panel or bypass gives the maintenance team a way to work on the changeover arrangement without taking the essential boards down.

Circuits that cannot tolerate even the seconds a generator takes to accept load are fed from uninterruptible supplies, and those are distributed through dedicated final distribution boards so that the protected supply is not quietly extended to general small power during later alterations. The low-voltage assemblies most often specified for this sector include:

• Main distribution boards at the intake, splitting essential from non-essential supplies
• ATS and MTS transfer panels for changeover to and from the standby generator
• Final distribution boards for wards, theatres, laboratories and imaging rooms
• Motor control centres and motor starter panels for chillers, pumps, air handling and medical gas plant
• Protection and metering panels giving fault discrimination and department level energy data

Environment, access and safe maintenance

Panels in a hospital sit in plant rooms, risers, basements and laundries, and the enclosure has to suit the location: sealed and gasketed where there is dust or wash-down, ventilated and derated where a plant room runs warm. Internal separation and clear, permanent labelling matter more than usual, because much of the maintenance has to be carried out while the building is occupied and only part of a board can be isolated at a time.

Motor control centres and motor starter panels for chillers, air handling units, compressors and pumps are usually placed in the plant room they serve. Variable speed drives such as Commander C, Commander S and NE-200 units are commonly built into these panels to soften starting currents and reduce running energy on fans and pumps.

Compliance and commissioning in Kenya

Assemblies are built to IEC 61439-1 and IEC 61439-2 under an ISO 9001 quality system, using switchgear components from Schneider Electric, ABB and Siemens. EPRA regulation covers the licensing of the contractors who install and connect the work, and KEBS certification applies to the equipment supplied. Protection panels and metering built around Rishabh instruments and current transformers give the estates team visibility of what each department is actually drawing.

Commissioning is where a hospital installation is proved: changeover behaviour, load shedding, generator acceptance and the response of each essential board to a simulated supply failure, all witnessed before the area is handed over. Panel Tech Systems manufactures in Nairobi and serves Kenya and across East Africa.