The carpenter's tool kit must be a matter of personal choice but it is best to start with a basic set of tools and add to them only when a special tool is needed. In all electrical equipment on building sites therefore which is to be hand held, the voltage should be reduced to a safe level. A very useful saw on a building site is the universal cross cut. This is basically the horizontal crosscut as is used on the mills. One of the problems in working under site conditions, which often means rough, is that of securing an overall accuracy within given tolerances over a number of small consecutive measurements, without accumulating errors. Levels given on site from the dumpy level are not likely to be in error, but it is sometimes necessary to take intermediate levels using a spirit level and a straight edge.