three black power wires are attached in parallel to an aerated concrete brick. electrical wiring in the wall of the gas block

power wire threecore cable electrical wiring wall private house stationary bare walls without repair electric section construction electrician insulation winding sheath deenergization polyvinyl chloride resistance conductor grounding thickness connection industry voltage disconnection mortgages sockets switch gas block aerated concrete brick fastening three black wires are attached parallel close-up brick close-up