One of the main reasons for stray voltage is the bonding of the primary and secondary neutrals of service transformers. This neutral is grounded locally at the customers’ premises, normally in the service panel. The National Electric Code (NEC) requires all metal casings of the electrical equipment on the premises to be bonded by equipment grounding conductors (EGC), which are also bonded to the utility neutral at the service panels. Thus, any metallic frame connected to this EGC will be at the neutral voltage of the premises.