Consumer unit to consumer unit

[andemz]

Having a discussion last night, with my Father, he was telling me how is electic is wired up in his house. The main point i want to focus on is his house and my nan's detached dwelling on the same land.

My Dad has a consumer unit but i don't know what kind, only 1 thick wire runs from his consumer unit to My Nan's consumer unit in her dwelling which is about 5 meters away from thier house.

Nan is partially sighted and so therefore is gond flor based only, she is also hard of hearing. 1 week ago the electricity tripped into my Nan's place thus causing My Parents house to trip. They like the fact that this happens as it alerts them to any fault within her dwelling. I can understand that but my question is asking how is this working and is this ok, how would you enable Nan's to Trip and not the parents.

Thanks in advance.

 

[Big_Spark]

adam, this should not actually happen in a properly designed and installed installation.

The way you can get the local preotective device to trip, without tripping the remote protecive device is correct choice of those devices.

For arguments sake.

Your Nans end has a 80A, 30mA RCD incomer, your granddad end also has a 30mA rated RCD installed to protect the cable between the properties.

The way to change this is to make the RCD at your Grandads end 100 or 300mA rated.

In the event of a fault, only the RCD at the Grans end will trip.

The same principle applies to MCB's and Fuses to a lesser degree.

It is hard to give a clearer picture without knowing the specifics of the installation, what the protective decives are, their ratings etc.