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TT earthing at kiosk and Barn Stable with large distance between both

Duncan G

I have an install on a field to do where the supply comes in from a power networks overhead pole transformer to a kiosk roughly 8 meters away, in the kiosk there will be the DNO cut out / supplier meter / 100A switch fuse.

From here there will then be a 70mm 4 core swa running underground 250 meters to the barn where it will terminate using 2 cores for phase and 2 cores for neutral to comply with voltage drop allowance.

My question is do I earth stake the Kiosk end for earthing at that end so as to protect the armouring of the swa and housings of the switch fuse then earth stake at the barn with earth separation of the SWA to prevent 2 earth paths and what precautions do i need to consider as there will be horses at the barn. Your comments will be greatly appreciated. 

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    If at all possible I would go for either a three phase supply, or split phase, as has already been said that will reduce the phase current, and also reduce voltage drop in the neutral.

    If the above can not be achieved, then you can probably apply engineering judgement and allow a lot more voltage drop than the norm.

    If the long cable from the transformer to the load belonged to the DNO, they might allow as much as 10% voltage drop in the service cable, and no one worries about that !

    250 volts at the transformer, and 226 at the load is common on rural supplies. If going down this route, consider the load profile, A long hour 100 amp load, with 10% losses in the cable is approaching £1 an hour, or perhaps £6,000 a year. Ten years losses would pay for the larger cable. If on the other hand the load is usually only 10 amps or so, with rare peaks approaching 100 amps, then the losses are relatively unimportant.

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    If at all possible I would go for either a three phase supply, or split phase, as has already been said that will reduce the phase current, and also reduce voltage drop in the neutral.

    If the above can not be achieved, then you can probably apply engineering judgement and allow a lot more voltage drop than the norm.

    If the long cable from the transformer to the load belonged to the DNO, they might allow as much as 10% voltage drop in the service cable, and no one worries about that !

    250 volts at the transformer, and 226 at the load is common on rural supplies. If going down this route, consider the load profile, A long hour 100 amp load, with 10% losses in the cable is approaching £1 an hour, or perhaps £6,000 a year. Ten years losses would pay for the larger cable. If on the other hand the load is usually only 10 amps or so, with rare peaks approaching 100 amps, then the losses are relatively unimportant.

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