Can the fence be used as ground?

Hello. We connect a plot with a summer house to the overhead line (technical connection). They planned to hang the SCHU (in it 4p VA 25A-3f counter-4p UZO 100mA) on the facade of the house. Misunderstood TU. Now we have SCHU on met. fence from the outside. SCHU is grounded to the fence and the pin into the ground. The act has not yet been signed. Is it possible to connect the VL-SHCHU pole with a SIP 4 * 16, the ShCH-facade again with a SIP 4 * 16 (15 meters by air), on the facade, switch to 5 * 10 copper through GAM16 / 10 sleeves from IEK, copper to the switchboard in the house. The main question, because we have everything listed in stock and we have only 4 conductors in the self-supporting insulated wire between the control panel and the house facade, is it possible to lay copper from the 5 * 10 wire on the facade to the nearest place on the fence, thereby using a fence (15-20log. m) as a grounding conductor? Logs are connected by welding along the entire length of the fence, every 2-3 meters a column at a depth of 1.5-2 meters, concreted. Thank.