Can a RCD be fitted to an old fuse box?

The rcd is not there just to protect the electrician (they should know how to work safely), it is there primarily to protect residents+pets from electric shocks. The cheapest way would be to fit an rcd to the meter tails between the meter and the fuse box or consumer unit, the only downside is that in the event of an earth fault you will loose all your supply (but at least you will be alive to reset it). Even if you have a consumer unit with trips, it is not alway possible to fit rcbo's (a breaker+rcd in 1 unit) due to the size. Regards, Terry.

Whilst it is possible to fit a separate RCD to the circuit or multiple RCD's, if more than one circuit is being altered, by far and away the best and most cost effective solution is to have a new Dual RCD and MCB fuseboard fitted.

An in-line rcd can be fitted to protect the board or online for individual circuits. The best option would be to update the fuse board to a dual rcd . In event of power loss some circuits will still be on with a dual rcd board .