There are two definitions of critical customers. One is a Critical Load Customer and the other is a Critical Care Customer. Neither of these types of customers are guaranteed a continuous power supply and should take care to ensure that essential services have alternate generation or plans in place to handle service interruptions.
Chronic Condition or Critical Care Customer
Any residential utility customer who has a person permanently residing in his/her home and who has been diagnosed by a physician as having a serious medical condition that requires an electric-powered medical device, or electric heating or cooling to prevent the impairment of a major life function through a significant deterioration or exacerbation of the person’s medical condition or to sustain life