Consumer Unit Upgrades
Nearly all new domestic electrical work will require RCD protection to comply with the current regulations. Many older consumer units (commonly known as fuse boxes) won't have RCDs, and so will need upgrading (ie replacing) before any work is carried out. RCDs are potentially life saving devices, so having them installed properly and in correct working order is crucial. The best way of complying with the current regulations when having new electrical work done is with a consumer unit upgrade.
Older Types Of Consumer Unit
If your fuse box looks like this, chances are there is no RCD protection to your property, and is an indication of the age of the electrics is your home. By itself, this does not imply the electrics are not safe. However, it would imply that a greatly improved safety factor would be achieved by simply changing to a new, metal, RCD protected consumer unit.
Different Types Of Newer Consumer Units
There are 2 main types of consumer unit available - Dual Split RCD consumer unit, and Individual RCBO consumer unit. Until recently, there has been a significant price difference between these two types of consumer unit, the Individual RCBO consumer unit being quite a lot more expensive to buy. The price difference led many to go with the cheaper option. However, lately the cost difference has become a lot less, so which do you choose?
What are the advantages/disadvantages of each?
Dual Split RCD Type
Uses 2 RCDs to cover 2 banks of circuits. Which means if any 1 circuit develops an earth fault, the RCD will disconnect all 5 circuits covered by this RCD.
The advantage is that it is the cheaper type of consumer unit.
Individual RCBO Type
Every individual circuit incorporates its own RCD (an RCBO is an MCB/RCD combo).
The advantage is that only the affected circuit will disconnect in the event of an earth fault.
In view of the above comparison, I would in most cases recommend the preferred option of Individual RCBOs, even though a little more expensive.