Our Mailing Address
California ISO
P.O. Box 639014
Folsom, CA 95630
Folsom campus
250 Outcropping Way, 95630
Main telephone number: (916) 351-4400
Security telephone number: (916) 351-2303
Alhambra campus
1000 South Fremont, 91803
Main telephone number: (626) 537-2700
Security telephone number: (626) 537-2710


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Contact us

Our business hours are Monday through Friday from 8 a.m. to 5 p.m.


Thank you for your interest in the California ISO. Your questions and comments are important to us. To speak to a representative during business hours, please contact the department below that can best address your inquiry:


Customer Services
(916) 608-7320 

Human Resources
(916) 608-7000 

Media Line
(888) 516-6397

(916) 608-5847

Finance and Accounting
(916) 608-5937

Click here to request a tour

System access or technical issues
(916) 351-2309 or (888) 889-0450

Don’t see what you need?

Submit the electronic request form below and a representative will contact you within 24 business hours.  Please review our Tips for Asking Questions of the ISO prior to submitting the form to find out how to get a timely and useful response.

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