RCD Tripping only on High Amp appliances

[sadpcd]

Hi all
We have 220V one phase power supply house with two floors
Suddenly the Floor 1 RCD, trips when connects ANY high amp devices to the house such as vacuum cleaner, refrigerator etc in any floor. Otherwise it works fine on small amp devices.Now I'm using my computer without any RCD tripping.
So we change it to a new RCD(Orange Electronics) in floor 1 and also i noticed that the new RCD does not trip when I press test button.
As I remember previous RCD (Havells) trips when I press the test button.
Also we separated the earth wires from the both switch board to prevent N-E connections. But the trip still triggers on any high Amp equipment.
Sorry I'm new to this subject

 

[PBC_1966]

Hello, and welcome.

Also we separated the earth wires from the both switch board to prevent N-E connections.

What exactly do you mean when you say you separated the earth wires from both boards?

 

[sadpcd]

Hello, and welcome.

Also we separated the earth wires from the both switch board to prevent N-E connections.

What exactly do you mean when you say you separated the earth wires from both boards?

I meant we separated every earth wire that comes to the switch board which is connected to a connector bar
also disconnected every devices from the plugs in every floor and to test we connect only one appliance like a vacuum cleaner or refrigerator

 

[PBC_1966]

So with all the earth wires to the branch circuits disconnected from the earth bar in the board, the RCD still trips when you run a higher-powered appliance? It sounds as though you have a neutral-earth fault on a circuit somewhere. It might be a damaged neutral in a cable somewhere coming into contact with something else, or a fault in a fixed appliance.

Really you need to start insulation testing on the branch circuits to locate the fault, but if you don't have equipment available you should be able to narrow down which circuit is causing the problem easily by disconnecting each neutral in turn (with the appropriate fuse removed or circuit-breaker open) and seeing if that stops the tripping.