Can we use the earthing system used for lighting arrest,as earthing for computers etc.?
By “earth”, it is assumed you are talking about the grounding system. Secondly, “lightning arrestors” are devices that are mounted to the circuit breaker panel. Even though they are grounded, they do not carry lightning to ground. They only protect sensitive equipment from high-level surges. I think you are referring to an isolated grounding system, such as is common in commercial buildings. When you have an isolated grounding system, all sensitive electronic equipment is grounded to that system, and nothing else. However, all grounding points will bond together at the main service entrance, or at your breaker panel. All grounding points include normal equipment ground, lighting protection ground, isolated equipment ground, water service ground, building steel ground, etc. etc. I repeat, they all bond together at the main electrical service entrance. Otherwise, a potential voltage is created between the separate grounding points. This is per Article 250 of the National Electrical Code
