A standard electric water heater has a two-pole breaker rated at 30 amps. The water heater is connected to a 240-volt circuit. It has a ground wire connected to the service ground and the other is connected to the water heater ground connection.
An electric water heater that is only giving cold water may have a tripped 30 amp circuit breaker. To determine if it has tripped the circuit breaker locate the circuit panel and look for signs; a tripped breaker can be identified by being in between the on and off position, but not fully on either. To reset, switch the breaker completely to the off position and then return it to the on position.