The U.S. electrical contracting industry is comprised of establishments primarily engaged in the installation and servicing of electrical wiring and equipment. Over 102,000 U.S. firms specialize in electrical contracting, with combined annual sales of over $96 billion. The industry is highly fragmented: a vast majority of firms claim less than $500,000 in annual revenue and fewer than 10 employees. Most work within a single market. Large firms within the industry include: EMCOR Group, Quanta Services and Integrated Electrical Services. In all, about 600 companies have annual revenue over $10 million.