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Class 2 CT chamber

lyledunn

New Form 4 switchboard but DNO want confirmation that the integral CT chamber is of Class 2 construction as per BS7671. No specific Reg given. It is not something that I have been challenged on before but I can only see some loose implication in 557.5.3.1 indent (iii). 

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    Morning Lyle

    No usual noways in my part of the world, UKPN land, for panel to have an inbuilt CT chamber. 

    The usual method is to bring in a multi-core SWA from the transformer in to the switchroom to supply a separate meter. The cable is provided by the DNO and the meter by the meter operator.

    Doing a job at the moment with an 800kVA TX in a GRP enclosure and an adjacent GRP enclosure with the Form 4 panel to supply a large EV charging installation.

    The Tx is in, the LV panel is in, 2 x 630mm AWAs connect the panel to the TX, meter cable in and connected to the meter, HV cables installed out to the grass verge adjacent to the roadway. However highway authority not authorising the excavation of the verge as there are already road works nearby replacing traffic lights. Having to wait for traffic light works to finish before the 2 x HV cables to be connected in to the HV ring. 

    Might be worth abandoning the existing CT chamber and going for the multi-way meter cable option?

    JP

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  • 0

    Morning Lyle

    No usual noways in my part of the world, UKPN land, for panel to have an inbuilt CT chamber. 

    The usual method is to bring in a multi-core SWA from the transformer in to the switchroom to supply a separate meter. The cable is provided by the DNO and the meter by the meter operator.

    Doing a job at the moment with an 800kVA TX in a GRP enclosure and an adjacent GRP enclosure with the Form 4 panel to supply a large EV charging installation.

    The Tx is in, the LV panel is in, 2 x 630mm AWAs connect the panel to the TX, meter cable in and connected to the meter, HV cables installed out to the grass verge adjacent to the roadway. However highway authority not authorising the excavation of the verge as there are already road works nearby replacing traffic lights. Having to wait for traffic light works to finish before the 2 x HV cables to be connected in to the HV ring. 

    Might be worth abandoning the existing CT chamber and going for the multi-way meter cable option?

    JP

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