| Schirg, Richard & Sons, Inc. | West Abington Township | PA | Subcontractor |
| Schmidt Electric Company, Inc. | Austin | TX | Subcontractor |
| Schwan Electric, Inc. | Aberdeen | SD | $0 |
| Scott Electric Co. Inc. | Greenville | MS | $0 |
| Scott Testing Inc. | Trenton | NJ | $0 |
| Scripps Ventures, Inc. | Tempe | AZ | $0 |
| Seacom Cabling Inc. | Everett | WA | $0 |
| Secure2ware Inc. | Valrico | FL | $0 |
| Securepro Inc. | Santa Barbara | CA | $0 |
| Security Gate And Access LLC | Puyallup | WA | Subcontractor |
| Seger Communications, Inc. | Buffalo | NY | $0 |
| Seigel Communications Service LLC | Moorhead | MN | Subcontractor |
| Select Electric, Inc. | Anaheim | CA | Subcontractor |
| Self Electric, LLC | Courtland | MS | Subcontractor |
| Self James Inc. | Pearl | MS | $0 |
| Sellers Electrical Contracting, Inc. | Baxley | GA | Subcontractor |
| Semo Communications, Inc. | Modesto | CA | $0 |
| Sentry Electric, Inc. | Lincoln | NE | $0 |
| Sentry Fire Protection, Inc. | Huntington | WV | $0 |
| Sequoyah Communications Inc. | Oklahoma City | OK | Subcontractor |
| Serat Enterprises Inc. | Temecula | CA | Subcontractor |
| Service Electric Co. | Albuquerque | NM | Subcontractor |
| S.e.t.i. Societa' Elettrica Telecomunicazioni Informatica S.R.L. | Scafati | | $0 |
| Seti Works S.R.L. | Calcinaia | | $0 |
| S.e.t. - Pacific, Inc. | Tamuning | GU | Subcontractor |
| Settle-muter Electric, Ltd. | Columbus | OH | Subcontractor |
| Shannon Electric LLC | Cleveland | OH | $0 |
| Shannon Industrial Contractors Inc. | Hayden | ID | $0 |
| Shaw Electric, Inc. | Davenport | IA | $0 |
| Shelley's Electrical Service, Inc. | Sebastopol | MS | $0 |
| Sherwin Electrical, LLC | Powell | OH | Subcontractor |
| Shizuru Electric Inc. | Honolulu | HI | Subcontractor |
| S.H.J. Electric Co. Inc. | Seatac | WA | Subcontractor |
| S & H Lone Star Electric, Inc. | Fort Worth | TX | $0 |
| Sidney Electric Company | Sidney | OH | Subcontractor |
| Sierra Electric, Incorporated | Pasco | WA | $0 |
| Sierra Nevada Electric Inc. | Auburn | CA | Subcontractor |
| Simply Controls Inc. | Olympia | WA | Subcontractor |
| Singleton Electric Company, Inc. | Gaithersburg | MD | Subcontractor |
| Sir Raleigh Electric, Inc. | Garner | NC | Subcontractor |
| Sistemas Y Soluciones De Telecomunicaciones S De Rl | Tegucigalpa | | $0 |
| Site On Sound Inc. | Fargo | ND | $0 |
| Sitewise Inc. | Huntingburg | IN | $0 |
| Skilled Computer Resources Corp. | Lebanon | IL | $0 |
| Skyline Electric Company | West Valley City | UT | Subcontractor |
| Skyline Services, Inc. | Springdale | AR | $0 |
| Smith Electric & Associates, Inc. | Mobile | AL | $0 |
| Societa' Ingegneri Verificatori S.R.L. | Bologna | BOL | $0 |
| Solar Connection, Inc. | Mission Hills | CA | $0 |
| Solarpark USA Inc. | San Ramon | CA | $0 |
| Solar States LLC | Philadelphia | PA | Subcontractor |
| Solutions-i3 LLC | Tucson | AZ | $0 |
| Sonora River Electric, LLC | Sierra Vista | AZ | Subcontractor |
| Sound Associates, Inc. | New York | NY | $0 |
| Sound Design Inc. | Plainfield | IL | $0 |
| Source Electric LLC | Port Orchard | WA | Subcontractor |
| Southeast Electrical Supply Inc. | Perry | GA | $0 |
| Southeast Electric LLC | Juneau | AK | $0 |
| Southern Arizona Electric, Inc. | Tucson | AZ | $0 |
| Southern Atlantic Electric Company, Inc. | Jacksonville | FL | Subcontractor |
| Southern Contracting Company | San Marcos | CA | Subcontractor |
| Southern Plains Electric Inc. | Lawton | OK | Subcontractor |
| South Florida Electric LLC | Fort Pierce | FL | Subcontractor |
| Southland Electric Co. Inc. | Birmingham | AL | $0 |
| Southland Electric, Inc. | San Diego | CA | $0 |
| Southwest Communication Systems Inc. | Springfield | MO | $0 |
| Southwest Networks Inc. | Irving | TX | $0 |
| Southwest Traffic Signal Service, Inc. | El Cajon | CA | $0 |
| Specialty Engineering, Inc. | Vancouver | WA | Subcontractor |
| Spectrum Electric, Inc. | Sweetwater | TN | $0 |
| Speelman Electric LLC | Tallmadge | OH | Subcontractor |
| Speros Holdings, LLC | Savannah | GA | $0 |
| Splicing, Terminating & Testing, Inc. | San Jose | CA | $0 |
| SRC Electric LLC | Elk Grove Village | IL | $0 |
| S & S Electric Solutions LLC | Salt Lake City | UT | Subcontractor |
| Staco Electric Construction Company, LLC | Kansas City | MO | Subcontractor |
| Staley, Inc. | Little Rock | AR | Subcontractor |
| St. Andrews Construction Services Corp. | Thornton | CO | $0 |
| Stans Electric Inc. | Cheboygan | MI | $0 |
| Star Electric Company, Inc. | Glen Burnie | MD | Subcontractor |
| Star Electric, Inc. | Fairbanks | AK | Subcontractor |
| Starlink Technologies LLC | Hazleton | PA | $0 |
| Star Technical Trading Services | Ras Zuwayed | | $0 |
| Stealthnetwork Communications, Inc. | Gig Harbor | WA | $0 |
| Steiner Electric Inc. | West Bend | WI | $0 |
| Stelco, Inc. | Altoona | PA | $0 |
| S. & T. Electrical International Inc. | Sault Sainte Marie | MI | $0 |
| Stelko Electric, Inc. | Kokomo | IN | $0 |
| Stellar Inc. | Carlsbad | NM | Subcontractor |
| Stephens Contracting Company, Inc. | Jena | LA | Subcontractor |
| Sterling Communication Technologies, Inc. | Parker | CO | $0 |
| Stewtel, Inc. | Eureka | CA | $0 |
| Stilian Electric Inc. | Methuen | MA | Subcontractor |
| Stilsing Electric, Incorporated | Rensselaer | NY | $0 |
| S.t.i.l. Societa' Tecnoimpianti Livornese S.R.L. | Livorno | LIE | $0 |
| Stone Electrical, Inc. | Loveland | CO | $0 |
| Stoner Electric, LLC | Milwaukie | OR | Subcontractor |
| Story Electrical Service, Inc. | Paducah | KY | Subcontractor |
| Stouter Construction, LLC | Emmitsburg | MD | $0 |
| Strategic Connections Inc. | Raleigh | NC | Subcontractor |
