If a service panel is fed with four 1 AWG copper conductors, what is the smallest GEC that can be installed to building steel?

The smallest Grounding Electrode Conductor (GEC) that can be installed to building steel, when the service panel is fed with four 1 AWG copper conductors, is determined by the National Electrical Code (NEC) guidelines. The size of the GEC is generally based on the size of the largest ungrounded conductors supplying the service.

In this scenario, with four 1 AWG copper conductors, the NEC provides a specific table (usually Table 250.66) that outlines the minimum size for grounding conductors based on the size of the service entrance conductors. For conductors that are 1 AWG copper, the minimum size for the GEC is 8 AWG copper.

Therefore, even though multiple choices are provided, the smallest GEC to be installed to the building steel, in compliance with the NEC, is correctly identified as 8 AWG. This size ensures proper grounding and protection of the electrical system, maintaining safety standards.