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Electrical upgrade for Grade II Listed building in Twickenham
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Eaton MEM panelboards and distribution boards were specified for the electrical refurbishment programme in one of the best-known buildings in the London Borough of Richmond upon Thames. The programme included replacing more than 30 MEM fused combination switch (FCS) units, installed more than 30 years ago and still working well, by two of the company?s latest MCCB panelboards.
York House Twickenham is a Grade II listed building that houses the Municipal Offices for the London Borough of Richmond upon Thames. The elegant building, dating back to the 17th Century, houses the Mayor?s Parlour, the Council Room, two public halls and committee rooms. Meanwhile the Civic Centre next door, opened in 1990, houses most of the Council Staff.
The programme to upgrade the electrical distribution system in York House involved replacing more than 30 FCS units in the main switchroom and a similar number of distribution boards around the building. These have been replaced by modern MCCB panelboards and MCB distribution boards respectively. At the same time old paper-insulated lead-sheathed sub-mains cables, that had been part of the original 1920s electrical installation, were replaced by modern cables.
The existing fused combination switches were all MEM units, installed in the early 1970s. They have been replaced by two of the latest Eaton MEM panelboards and Series G moulded-case circuit-breakers. MCCBs require little or no maintenance, trip safely to protect a circuit and can be reset safely and easily by staff with limited electrical expertise, explains Paul Cook, Facilities Manager for the London Borough of Richmond upon Thames. The panelboards are designed around the Series G MCCBs. The panelboards and devices are independently certified by KEMA to the international switchgear standard IEC60947-2.
The main panelboard is an 18-way unit with a 250A MCCB incomer. Most of the outgoing circuits have 63A three-phase MCCBs but there is also a 160A MCCB supplying a new kitchen area and a 200A device feeding the existing switchgear. There is 25-30% spare capacity.
The second panelboard is a smaller, six-way, essential services panel feeding computers, emergency lighting, the Council Chamber and one of the large public halls. These can be fed by a newly-refurbished 80kVA diesel generator to ensure that important Council meetings can proceed in the event of a sustained power failure.
New Memshield 2 distribution boards have been used throughout. These are mainly 12-way Type B (three-phase) units and replace two or three old single-phase MCB distribution boards in each location. Single-phase distribution had tended to result in unbalanced loading across the phases says Paul Cook. While the use of MCBs for final circuit protection was forward-thinking in the 1970s, the old distribution boards did not have a main switch for isolation whereas the new Memshield 2 boards all have incoming isolators.
RCBO (combined MCB and residual current) protection is provided on each outgoing power circuit, not only for personal safety but also to reduce the fire risk in the Grade II listed building. 30mA devices are used where personal protection against electric shock is paramount and 100mA devices where fire is the principal risk.
The Grade II listing meant that work had to be carried out with a minimum of structural change. Existing ducts and cable routes had to be utilised wherever possible. This called for weekend working to allow power to be switched off while old cables were withdrawn and new cables drawn in.
A third panelboard has been installed in the neighbouring Civic Centre where the requirements of modern computer installations have outstripped the original electrical provision, necessitated reinforcement of the electricity supply. The EDF substation has been upgraded from 500kVA to 1MVA and the communications centre has an 80kVA UPS system and a new 250kVA emergency generator.
The electrical upgrade for York House and the Civic Centre has been designed and managed by its own Facilities Manager, Paul Cook, and the installation work has been carried out by EDF Contracting.
?If the new Eaton MEM equipment serves as well as the old MEM switchgear, that has been in use for more than 30 years, we will be more than happy? says Paul Cook. He chose Eaton MEM panelboards and distribution boards because they are solid and reliable and offer the range of features which were needed. They are also designed with the needs of the installer in mind.
