I get called to many a house in Leeds these days to offer advice and a site survey on the existing state of electrics before the purchase of a new electric shower is undertaken.
Sometimes the customer does not call a electrician until they have bought the new shower and this is where the problem starts as in most cases have to be the bearer of bad news and tell them they cannot have it fitted until they bring the rest of the installation up to standards for safety and regulation reasons.
The situation is usually always commonly the same, a ageing Wylex BS3036 re wirable consumer unit as illustrated to the right, this type of fuse board was fine two decades ago but offers no RCD protection now which is mandatory on circuits especially those within a special zone like a bathroom.
In order to comply with the regulations and to sign the installation off as safe to use by the customer I have to upgrade the entire consumer unit, main under rated supply tails and check the Main Earthing conductors are sufficiently sized to 10mm2.
This is why electricians never quote over the phone, its not that they are being awkward, it is simply each house is different and some older and newer than others. Not all houses need the electrics upgrading before further works can be installed just mainly older houses.