Surface · ESP
Junction Box
A vented box at surface where the cable from the well meets the cable that runs to the transformer and drive. Also called a vent box.
What it does
Lets gas that migrates up inside the power cable escape to atmosphere before it reaches the drive, cutting fire and explosion risk. It is also the access point for electrical tests of the downhole equipment.
Basics
| Location | Between the wellhead and the drive |
| Main job | Vent gas from the cable |
| Also used for | Insulation and continuity tests |
Common failures
- Blocked vents that let gas reach the drive
- Loose or corroded terminals
Troubleshooting
- Symptom
- Gas smell or reading at the drive cabinet
- Likely cause
- Junction box not venting or bypassed
- What to check
- Inspect vents and cable path; never bypass the box