Since 1976, Mark III has evolved from a single-trade electrical contractor to a MEP construction and service company delivering projects across California.

The Mark III Story

On January 1, 1976 in a Denny’s restaurant in Sacramento, Mark O’Brien sat down with Buzz Oates and Charlie Massie to discuss a business opportunity that would lead to a long-term partnership. Mark shared his vision to build an electrical subcontracting company, and Buzz and Charlie agreed to invest. The company was conceived that morning inside Denny’s. They would name it “Mark III Construction,” representing each of the original three investors.

Mark found himself running a company with no experience handling payroll or purchase orders. His first hire was his brother, Tim, followed by an accountant, his neighbor. Soon after, they were a team of 25.

Their days were spent in the field and their nights were spent doing paperwork. Within months, Mark saw an opportunity to expand beyond electrical work, adding mechanical and plumbing trades to their operations – the “Power of One” approach was born. Fast-forward to present day, Mark III remains a family-owned company and continues to operate within the same building where it opened in 1976, with an additional office in Fresno.

“Find out what you’re great at and make it your lifelong profession.”

Mark O’Brien, Founder

Over The Years


Mark III is founded and shares a small office space with Buzz Oates and Charles Massie off Florin Perkins Road – the company’s material yard only 10 x 20 ft.


Mark III outgrows their small space and relocates to an office roughly 2 miles away off Signal Court.


Five years later, Mark III is granted the opportunity to move back into the Florin Perkins office as Buzz Oates separates his development company. This time, Mark III rents the entire building but shares offices with employees from the “Lumber Jack.”


Mark III purchases the building and takes over the entire office.


Mark III purchases the adjacent building to house the fabrication team until 2019.


New owner, Dan Carlton, shifts company focus to MEP subtrades.


Mark III opens additional office in Fresno, CA.


Mark III updates mission, vision, and core values.

Additionally, Mark III purchases new office to house growing Fresno team, and team relocates to larger space with a dedicated warehouse.


Chief Financial Officer, John Cassidy becomes partner and Mark III opens MEP Manufacturing Facility in Power Inn District.

Mark III’s Logo: Over The Years

Contact Us

Corporate Office

5101 Florin Perkins Road
Sacramento, CA 95826
Phone: 916-381-8080 Fax: 916-386-0363

Fresno Office

5252 E. Home Avenue
Fresno, CA 93727
Phone: 559-353-2744 Fax: 559-840-1460