Two good texts are Paul Gillâ€™s Electrical Power Equipment Maintenance and Testing, and NETA Maintenance Testing Specifications for Electrical Power Distribution Equipment and Systems but they are not exactly breezy reading without some understanding of power-systems engineering practices. Gill teaches his material through George Washington University in DC. NETA has conferences around the US.
You may want to get on the training mail list of a firm like Electro-Test. They have branches in your state and gave various 1-4 day programs by way of introduction. Utilities and petrochems tend to have their own in-house operations for switchgear and related systemsâ€™ maintenance.