A landfill site supplied from private transformer has asked us to connect a back up generator to a changeover switch in the weighbridge. I’ve had a look at BS7430 7.2.1 and it says an earth electrode with resistance of 20ohms or less is required. This is potentially quite difficult to achieve. It is a lot lower than the BS7671 requirement to be considered reliable. What is the reason for such a low figure and does it apply equally to private supplies as public supplies?
