Record any on-site supply redundancies that can provide energy or water if the primary supply is disrupted (e.g., a diesel generator backing up utility electric power). For each redundancy, note its start-up time, estimated runtime given the loads it supports and any stored or otherwise available resources, system reliability, and whether it is configured for automatic start in response to a disruption. If two components operate in sequence (e.g., an uninterruptible power supply and a generator), enter them as a single supply redundancy (e.g., “UPS + generator”). Use the TRN Toolkit's runtime calculators if you do not already know the estimated runtime.

For intermittently delivered supply types, such as fuel oil and propane, only the portion of fuel stored onsite that remains at the time of scheduled or threshold-based deliveries should be considered as a supply redundancy (i.e., the minimum supply on-hand). For these supply types, only the estimated runtime associated with that remaining fuel is required; the reliability and start-up-related questions are not applicable.