Several new excitation and load models are proposed for electromagnetic analysis in the context of a Galerkin-type large-domain (higher-order) boundary element method (BEM) or Method of moments for structures composed of thin wires, metallic surfaces, and imperfect inhomogeneous dielectric bodies. The models represent a natural generalization of point-delta generators and loads for wires. They are used for excitation and loading of metallic quadrilateral surface elements and dielectric hexahedral volume elements, and are termed line-delta and surface-delta generators and loads, respectively. The corresponding Galerkin generalized impedance and voltage matrix elements are derived and incorporated in the large-domain BEM outlined in the paper. The accuracy and usefulness of the proposed excitation and load models are illustrated on a number of characteristic examples. It is believed that these models can also be included in other BEMs for analysis of electromagnetic systems in frequency domain with comparable advantages.