Small generators are in the main designed to run one item in the same way as a bathroom shaver socket. With a single item earths are not so much a problem but once you use the generator to run a number of items then earths and earth leakage trips need to be provided. With a mains supply one can use a earth loop impedance meter to check the resistance of an earth rod but this will not work with generators so one has to use the special earth rod test set using the pair of test spikes to test the earth.
Also not all 110/230 volt generators do as they should and connect the neutral to earth some have the earth connected to a centre tap on one of the twin winding giving 55 – 0 – 165 volt instead of 0 – 220 volt. These generators should only really be used on the 110 volt setting.
Even on the 110 volt setting there are problems in that you have a split phase supply which means double pole MCB’s and switches on all circuits.
So one does have to be careful RCD’s that will work on 55 – 0 – 55 volts are available but not so common and not seen any RCBO’s that will work on reduced low voltage.
With all this in mind I am a little wary of recommending how to wire. Remembering the special lengths that are required when earthing this type of building as shown in the 17th Edition. I would not consider this a DIY job.
Your request is rather vague and you say Radial circuit but not what it is to power? As to lighting I would favour extra low voltage and 25 volt would seem in order.
Maybe you can tell us a little more about what is required?
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