Domestic work is any work that is to be done in houses or flats, etc. the type of work that could be done varies all the way from fitting a bulb to a full house re-wire and board change.
In older homes, many of them do not have a means of earth into their gas and water pipes which can be very dangerous if a line conductor touches them the exposed parts will become live. A fault we find in many homes is something called a borrowed neutral, which is common in old lighting circuits. It is when a light fixture is connected to the line from one circuit and neutral from another