| Next Service Inc | C10 + C20 | 2023 | Active |
| Ng's Electrical Inc | C10 + B | 2019 | Active |
| Norcal Fire Technologies Inc | C10 + C7 | 2026 | Active |
| North Coast Electric And Construction Inc | C10 + B | 2006 | Active |
| Northwest Security Inc | C10 | 2007 | Active |
| O'Driscoll J Electrical Inc | C10 | 2004 | Active |
| O'Keeffe Mechanical Co Inc | C10 + B, C4, C20 +4 | 1994 | Active |
| Oak Electric Inc | C10 | 2010 | Renew by Nov 30, 2026 |
| Occidental Power Solar & Cogen | C10 + B, C46 | 1990 | Active |
| Odinson Electric LLC | C10 | 2019 | Active |
| Omega Electric Group | C10 | 2022 | Active |
| Pacific Auxiliary Fire Alarm Company | C10 | 2023 | Active |
| Paganini Communications Inc | C10 | 1999 | Active |
| Paganini Electric Corporation | C10 | 1975 | Active |
| Pagco Construction Inc | C10 + C16, C36 | 1995 | Active |
| Pauric Electric LLC | C10 | 2009 | Active |
| Phase One Fire Life Safety Systems Inc | C10 | 2024 | Active |
| Phoenix Electric Company | C10 + A | 2002 | Active |
| Pilot Construction Management Inc | C10 + A, ASB, B +2 | 2009 | Active |
| PK Electric Inc | C10 | 2026 | Active |
| Plus General Construction Inc | C10 + B | 2006 | Active |
| Polr Electric Inc | C10 | 2010 | Active |
| Poly - On Electrical | C10 | 2018 | Active |
| Poly - On Fire Protection Inc | C10 | 2007 | Active |
| Potrero Energy | C10 | 2025 | Active |
| Power In Electric Inc | C10 | 2014 | Active |
| Prague Property Management Inc | C10 + B, C36 | 2014 | Active |
| Q & Q Electric Company Inc | C10 + B | 2005 | Active |
| Q 5 D | C10 | 2005 | Active |
| Quality Of Light Inc | C10 | 2022 | Active |
| R & K Electric Maintenance | C10 | 2022 | Active |
| R C M Electric Inc | C10 | 2023 | Active |
| Ra Electric LLC | C10 | 2018 | Active |
| Ranger/Liffey JV | C10 + A, C4, C31 +1 | 2021 | Active |
| Rectified Ev Charging & Electrical Services LLC | C10 | 2023 | Active |
| Red Hill Inc | C10 | 2025 | Active |
| Reichel C R Engineering Co Inc | C10 + C4, C16, C20 +3 | 1957 | Active |
| Reinhardt Construction Solutions LLC | C10 + B | 2015 | Active |
| Reliance Engineering Inc | C10 + A, HAZ | 2004 | Active |
| Revive Electric | C10 | 2025 | Active |
| RF Fire Alarm Pro Inc | C10 | 2024 | Active |
| Richard Albert Electric Inc | C10 + C7, D34 | 2020 | Renew by Dec 31, 2026 |
| Rick Electric & Construction Inc | C10 + B | 2025 | Active |
| Riv Electrical Inc | C10 | 2025 | Active |
| Rocca A M Inc | C10 + A, B, C36 | 1998 | Renew by Dec 31, 2026 |
| Rockland Construction Group Inc | C10 + A, B, C16 +3 | 2014 | Active |
| Rogers Brian Electric Inc | C10 | 2000 | Active |
| Rogers Mal Electric Inc | C10 | 1995 | Active |
| Rong Jian Design Build Inc | C10 + B | 2026 | Active |
| Roofworx Inc | C10 + C39 | 2022 | Renew by Dec 31, 2026 |
| RSB Construction Group Inc | C10 + A, B, C16 +2 | 2022 | Active |
| Rubecon Builders Inc | C10 + A, B, C5 +3 | 1997 | Active |
| Ruby Plumbing & Electrical Supply Inc | C10 + B, C16, C36 | 1998 | Active |
| Ryz Electrical | C10 + B, C36 | 2020 | Active |
| S & W Electric Inc | C10 | 1991 | Active |
| S And L Tec Construction Company Inc | C10 + B | 2009 | Active |
| S F Garage Company Inc. | C10 + A, B, C4 +2 | 1994 | Active |
| S L Electrical Contractor Inc | C10 | 1999 | Active |
| S W E Associates Inc | C10 | 2010 | Active |
| S W L Electric Inc | C10 + B | 2006 | Active |
| Safe SF Electrical Barahona Inc | C10 | 2023 | Active |
| Samco Construction Inc | C10 + B | 2007 | Active |
| San Fran Electric | C10 | 2024 | Active |
| Sanchez Electrical Corp | C10 | 2023 | Active |
| Sasso Construction Inc | C10 + B | 2008 | Active |
| Security Bay Area LLC | C10 | 2024 | Active |
| Sederap's Drywall Inc | C10 + B, C9, C36 | 2008 | Active |
| Seismic Retrofitters Inc | C10 + B, C36 | 1998 | Active |
| Sequoia Plumbing And Mechanical Inc | C10 + C36 | 2026 | Active |
| Serch Electric Co | C10 | 2018 | Active |
| Shadow Electric LLC | C10 | 2023 | Active |
| Shao Fat Construction Inc | C10 + B | 2005 | Active |
| Sierra Electric Co | C10 + B | 1959 | Active |
| Skyland Construction Inc | C10 + B | 2002 | Active |
| Skytec General Engineering | C10 + A, B, C16 +2 | 2023 | Active |
| Skytech Construction Inc | C10 + B, C36 | 2020 | Active |
| Smartlux Electric Inc | C10 | 2021 | Active |
| Solen Energy Inc | C10 | 2021 | Active |
| Sparkie Solutions | C10 + B | 2026 | Active |
| Sparkye Inc | C10 | 2025 | Active |
| Sure Inc | C10 + B | 1989 | Active |
| Surtec Construction Company Inc | C10 + A, B, C16 +2 | 2009 | Active |
| Sutro Power | C10 + B | 2020 | Active |
| T & T Electric Corp | C10 | 2023 | Active |
| T L Electric LLC | C10 + B | 2020 | Active |
| Tailwind Construction Inc | C10 + B, C36 | 2023 | Active |
| Tam's Electric Inc | C10 | 1989 | Active |
| Tanko Lighting | C10 | 2014 | Active |
| Teevan Company | C10 + B, C29, C33 +3 | 1975 | Active |
| Tello Electric Power | C10 | 2025 | Active |
| Teo Silva Electric Inc | C10 | 2025 | Active |
| The Process Company | C10 + B, C36 | 2025 | Active |
| Titan Construction Inc | C10 + B | 2010 | Active |
| TP Electric LLC | C10 | 2024 | Active |
| Traube Construction Company | C10 + B, C20 | 2012 | Active |
| Trulysun Energy Corporation | C10 + C46 | 2021 | Active |
| TWC Design & Construction Inc | C10 + B | 2024 | Active |
| U S Electric Technologies Inc | C10 | 1995 | Active |
| United California Access & Security | C10 + B, C7, C13 +3 | 2008 | Active |
| United California Glass & Door | C10 + B, C7, C13 +5 | 1991 | Active |