Ammeter all of the current flows through the shunt, and only a small fraction flows through the meter. This allows the meter to measure large currents. Traditionally, the meter used with a shunt has a full-scale deflection (FSD) of , so shunts are typically designed to produce a voltage drop of when carrying their full rated current. To make a multi-range ammeter, a selector switch can be used to connect one of a number of shunts across the meter. It must be a make-before-break switch to avoid damaging current surges through the meter movement when switching ranges. A better arrangement is
Electrical contractor classified by three major types of work performed. Electrical contractors employ workers in many capacities, determined by their level of training and experience. Some common jobs include: In the United Kingdom, the two main trade associations are the Electrical Contractors' Association, covering England, Northern Ireland and Wales, and SELECT - the Electrical Contractors' Association for Scotland. The main certification bodies are the National Inspection Council for Electrical Installation Contracting and Elecsa. The National Electrical Contractors Association (NECA) is the largest trade association in the electrical contracting industry, with about 4500 members. NECA publishes an industry magazine, and sponsors an annual