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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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    Red diesel fuel is often used very wastefully because it is so cheap.

    The requirement to use the more expensive white diesel for some applications will probably reduce consumption.

    Construction site equipment is often left idling all day to save the trouble of starting it.

    And at present even white diesel is cheaper than the market price for grid electricity. White diesel is currently up to about £1-60 a liter. A reasonably efficient modern diesel generator produces about 4 kwh per liter of fuel consumed. So the fuel cost is about 40 pence a unit.

    The open market price for grid supplied electricity is about 60 pence a unit, not the !capped" domestic rate or existing fixed price deals, but the market price for new customers or those transferred from bust retailers. 

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  • 0

    Red diesel fuel is often used very wastefully because it is so cheap.

    The requirement to use the more expensive white diesel for some applications will probably reduce consumption.

    Construction site equipment is often left idling all day to save the trouble of starting it.

    And at present even white diesel is cheaper than the market price for grid electricity. White diesel is currently up to about £1-60 a liter. A reasonably efficient modern diesel generator produces about 4 kwh per liter of fuel consumed. So the fuel cost is about 40 pence a unit.

    The open market price for grid supplied electricity is about 60 pence a unit, not the !capped" domestic rate or existing fixed price deals, but the market price for new customers or those transferred from bust retailers. 

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