The Conceptual Survey of Electricity and Magnetism (CSEM) is a widely used multiple-choice instrument measuring a student's conceptual understanding of electricity and magnetism. This study applied modified module analysis (MMA) and modified module analysis--partial (MMA-P), network analytic methods that identify groups of correlated responses, to CSEM data from two institutions (N=2538 and 3595). In module analysis, groups of correlated responses are called "communities." As in previous applications of MMA and MMA-P to mechanics conceptual inventories, a number of communities related to physics concepts and some communities related to the structure of blocked items in the inventory were identified. An item block is a set of items all referring to each other or to a common stem. Many blocked communities involved responses where the response to the later item would be correct if the response to the earlier item was correct. This suggests a modified scoring rubric for the CSEM is needed to account for these connections between items. A modified scoring rubric is proposed; however, the modified overall average scores changed by less than 1%. The communities of incorrect responses to the CSEM related to physical concepts had varied explanations. These explanations ranged from seemingly straightforward errors (the electric field pointing to higher potential or reversing the right-hand rule), to misconceptions about Newton's 2nd and 3rd laws carried over from mechanics, to naive reasoning conflating general topics in electricity and magnetism. The identification of incorrect communities allowed the computation of misconception scores showing how prevalent the misconceptions were in the classes studied.