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Very long run of LV Cabling

fiftyhertz

Hi all,

 

im looking at a project where the landlords LV cut out is approx 850 metres from the proposed tenants installation. The earthing arrangement is TT and protected by a time delayed 300ma RCD and a 63A MCCB.

 

The landlords sub main is going to be 2 x 4C 95mm2 in parallel buried in the ground to supply 20KVA worth of power. This achieved a volt drop of 1.6% which leaves 1.9% VD for lighting. From my Amtech calcs I also get about 1ka at the load Dis board (Phase fault)

 

im not worried about Earth Loop because of the RCD, but i am thinking about the adibatic of the phase conductors. If the tenant puts a long run of cabling in, this will comply from a Zs perspective, but could there be issues with the line under a phase to neutral /phase to phase fault as the cable could slowly cook under a lowish load without tripping the breaker. Is this a valid concern? Amtech isn’t throwing up any faults, but just wanted your thoughts.

 

thanks in advance

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  • 0

    As announced in the 2020 budget, the red diesel reduction of scope has been coming for a while, although the reduced tax rate will remain, for now, for forestry and farming and non-commercial heating. 

    Building sites, commercial heating, generators at pop festivals and so forth will need to switch to DERV and pay duty at that rate. As you say that alters the economics quite sharply.

    Why do you think industrial estate roofs are being plastered with solar panels etc for the last 2 years and folk like aggreko and pytch are practising towing pre-charged batteries onto festival pitches so the thing can run on inverter for half the time instead of burning half a litre of diesel per head per weekend  ? 

    Economic stimulus works, - round here  there can't be many square feet of sawtooth roofs left to do, and the tow on battery pack idea  is certainly taking off.

    Mike

     

Reply
  • 0

    As announced in the 2020 budget, the red diesel reduction of scope has been coming for a while, although the reduced tax rate will remain, for now, for forestry and farming and non-commercial heating. 

    Building sites, commercial heating, generators at pop festivals and so forth will need to switch to DERV and pay duty at that rate. As you say that alters the economics quite sharply.

    Why do you think industrial estate roofs are being plastered with solar panels etc for the last 2 years and folk like aggreko and pytch are practising towing pre-charged batteries onto festival pitches so the thing can run on inverter for half the time instead of burning half a litre of diesel per head per weekend  ? 

    Economic stimulus works, - round here  there can't be many square feet of sawtooth roofs left to do, and the tow on battery pack idea  is certainly taking off.

    Mike

     

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