Measuring Power Outages

I suspect that, like your Editor, most readers will have never heard of measures of the reliability of electricity supply. However, after the second worktime power outage in two days, GallonDaily decided to investigate. In our province the Ontario Energy Board is conducting a consultation among all municipal distribution utilities on the best way to measure the frequency and length of power outages. The OEB, in common with most other electricity regulators and jurisdictions around the world, already uses a set of measures known as System Average Interruption Duration Index (SAIDI) , System Average Interruption Frequency Index (SAIFI), and Consumer Average Interruption Frequency Index (CAIFI). These are international standard ways of measuring the frequency and duration of power outages from The Institute of Electrical and Electronics Engineers. The problem is that, at least in Ontario and we suspect in many other jurisdictions, they are not used in a very standard way and the indices are not as comparable as they should be between Local Distribution Companies.

GallonDaily believes that business and household users of electricity should also be consulted by the OEB on how power outages should be measured. Our view is based on the philosophy that when problems get measured and the measures get communicated then the problems get fixed. In other words, we are fed up with power outages affecting our office and we are going to raise a little bit of heck to bring attention to the problem.

The Ontario Energy Board publishes SAIDI, SAIFI, and CAIFI for each municipal utility in its Yearbook of Electricity Distributors. The 2010 issue will be out soon. If you are interested in this subject, the Ontario Yearbook of Electricity Distributors for 2009, packed full of facts that you never knew existed about Ontario Local Distribution Companies, is at

Information for the Ontario Electricity System Reliability Standards consultation process (which is actually open to all) is at

If the interpretation of SAIDI, SAIFI, and CAIFI (we prefer to think of them as a mutant form of Veni, Vidi, and Vici) is not clear (and why would it be?) then we refer you to  for a very good explanation. (Yes – that is the magazine of the Maharashtra State Electricity Distribution Co. Ltd.).

Watch for more information on outages from municipal utilities in an upcoming GallonDaily article.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s