Good info but a working example of the question using the adiabatic equation would have made it better. Surely if you need to ask the question then you need to read up your regs or wonder whether you should be doing this job. As it’s from a generator would it be advisable to make it a tt system and introduce a earth rod at both the generator and cable end location good working out, however if my calculation through up a 10mm earth I would still install a 16mm earth as standard practise, that way i know the install will be safe

size should the earthing conductor be? | Voltimum What size should the earthing conductor be? | Voltimum

If you use 54.7 the earthing conductor would be 1/2 of the line conductor ie 120mm. Its based on one line conductor as it is fault current to earth we are looking at. Would I consider sizing it to half of the combined area of the 3 (240mm2) size as in half of 720 mm2 or half of each 240mm2 . Guidance on earth conductor and protective bonding conductor cross-sectional areas is given in the guide to the wiring regulations BS7671. The whole point of an Adiabatic equation is to save money over hundreds of cable runs ! THAT'S IT. If your doing one or two runs and the cost isn't important then fair enough, use the standard size in the wiring regs as a guide. So it is either 60 sqmm or 360 sqmm. Or poss less by calculation. But typically the NICEIC won’t tell you but just refer to regs. Perhaps they don’t know how to do sums!

16mm Earth Cables

When calculating the size of the protective conductor do I use Table 54.7 or the Aidabatic equation? For your convenience, we cut to the length you require. Simply select the number of metres you require.

Cable - 6mm, 10mm and 16mm - TLC Direct 6491X Single Core Cable - 6mm, 10mm and 16mm - TLC Direct

Displaying products for 16mm Earth Cables - from our range of leading brand manufacturers. Sky Twin Cables c) Where practicable, the connection to the gas, water, oil, etc service should be within 600mm of the service meter, or a point of entry to the building if the service meter is external and must be on the consumer’s side before and branch pipework and after any insulating section in the service. The connection must be made to hard pipework, not to soft or flexible meter connections. is a non standard size protective conductor size, so the next size up is 10mm2 is acceptable, which saves money installing a 16mm2. A qualified electrician will understand the Adiabatic is the last part of any electrical calculation. After that test & inspect.Not really sure you answered the op's question there, I mean a 2.5mm earth might not cut it for 1200A generated current! I have an install involving 3 four core SWA of 240 mm2 feeding an MDP from a generator.The load is 1200 amps. The most typical method chosen is selection, in accordance with table 54.7 and the size selected is based on the cross-sectional area of the line conductor. For 25mm tails this results in a 16mm main earth. Using regulation 543.1.3 and the calculation method, the size of the protective conductor chosen is typically smaller than through selection. In the situation, you describe the calculation would need to be completed to determine whether the earthing conductor is adequate.