Comments by "Ted Sanders" (@surferdude642) on "Main electrical panel explained - Load center - service panel" video.

Neutral and ground must be connected together only at the main panel and no where else, including sub panels. The reason is to guarantee a 0 voltage reference point. This is necessary for the circuit to operate safely and for circuit breakers to trip when needed.
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@igorivanov7232 I'm not sure where you live, I'm in the US where we have a 120v system by center tapping the secondary windings of a 240v coil and hence the return or neutral wire. 240v is commonly used for high power appliances by connecting to opposite poles and omitting the center tap. In this case there's no neutral wire and the return shifts with the frequency from one pole to the other. Both are hot wires. You may have a loose hot wire that is making contact with metal somewhere in your system. You should call a local electrician to fix it. Changing the receptacles may do it, but a grounding rod will not help. You'll need an equipment grounding conductor to provide a fault path from the equipment to complete the circuit and trip the breaker. A grounding rod is mainly used to direct external current, lightning strikes, to earth.
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