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Critical Day / OFO Frequently Asked Questions

Critical Day
A Critical Day can be called whenever it is necessary to maintain the operational integrity of our system. Nicor Gas may declare a Critical Day when any of the following five conditions occurs or is anticipated to occur:

  • We experience failure of transmission, distribution, gas storage or gas manufacturing facilities.
  • Transmission system pressures or other unusual conditions jeopardize the operation of our system.
  • Our transmission, storage and supply resources are being used at or near their maximum rated deliverability.
  • Transporters or suppliers call the equivalent of a Critical Day.
  • We are unable to fulfill our firm contractual obligations or it is necessary to maintain the overall operational integrity of all or a portion of our system.

Operational Flow Order (OFO)
Customers and Suppliers will be notified of any OFO at least two hours before the Gas Industry Standards Board nomination deadline on the interstate pipelines with the company's facilities.

What should I do?
Because storage withdrawals will be limited on a Critical Day, customers may want to contact their suppliers/brokers to confirm that their supplies have been nominated to Nicor Gas and that Nicor Gas has confirmed their delivery. 

Transportation customers will be required to transport supplies which meet the obligations as defined by their service selections, and can change their nominations until 8 a.m. on the day the nomination change is to be effective.  For example, on a Critical Day if a customer's anticipated usage is greater than their contracted storage selection from Nicor Gas plus the confirmed deliveries to Nicor Gas on that day, the customer should try to increase their confirmed nomination or reduce their usage. 

A Critical Day is the only time that Unauthorized Use charges at $6 per therm, plus the higher of either the Gas Cost or the market price per therm, can apply.  If you have any questions or would like more information, please call our Gas Transportation Customer Service Center at 630.983.4040 and choose option one.

How will I be notified?
A Critical Day will be declared by 8 a.m. the day before the Critical Day occurs.

Customers and Suppliers will be notified of any OFO at least two hours before the Gas Industry Standards Board nomination deadline on the interstate pipelines with the company's facilities.

Nicor Gas will notify suppliers of a Critical Day or OFO by posting and on a recorded dial-in message.  To hear the message, call 630.983.4040, and choose option three.