| A & H Mechanical | 618-874-5588 | |
| A-Age | 618-234-4336 | a-age@sbcglobal.net |
| Alert Electric | 618-644-9333 | |
| All Purpose Erectors | 618-537-7777 | |
| Alternating RJ Electric | 618-696-9234 | |
| Barton Electric | 618-654-6626 | bartonelectricinc.com |
| Bel-Clair Electric | 618-539-5200 | |
| Electrico Inc. | 618-538-9500 | |
| Gilbert Electric | 618-458-7235 | |
| Glaenzer Electric | 618-277-2500 | glaenzerelectric.com |
| Guarantee Electric | 618-452-6122 | geco.com |
| Jarvis Electric, Inc. | 618-806-0217 | jarvis-electric.com |
| J. F. Electric | 618-797-5353 | jfelectric.com |
| Laughlin Electric | 217-246-4113 | |
| Lil Rock Electric | 618-556-8383 | |
| Litteken Electric, Inc. | 618-228-7144 | |
| Lowry Electric | 618-343-4200 | |
| M.A.C. Electric | 618-632-6672 | |
| MC Electric | 618-282-7788 | mcelectric-inc.com |
| North County Electric | 618-282-2749 | northcountyelectricinc.com |
| O'Fallon Electric | 618-632-3577 | ofallonelectric.com |
| Pfeffer's Electric | 618-588-4593 | |
| Pyramid Electric | 618-632-1180 | pyramidelectrical.com |
| Sachs Electric | 618-655-0627 | sachsco.com |
| Sutterfield Electric | 618-655-9406 | |
| Tucker Electric | 618-398-3676 | tuckerelectrical.com |
| Wissehr Electric | 618-398-7575 | wissehr.com |