How to Replace the ISGUS 24hours Timer with the BCT2 (240V Digital Timer) – Complete Bolec Conversion Kit Guide
The ISGUS 24hours mechanical timer has been widely used in irrigation, pump control, and industrial panels for decades.
It is a gear-driven mechanical timer that operates without any electrical power, using precision internal mechanisms for timing.
However, production has been discontinued and spare parts are now limited.
This article explains how to safely and effectively replace an ISGUS timer with the modern Bolec BCT2 (240V Digital Timer) using the dedicated conversion kit.
1️⃣ About the ISGUS 24hours Timer
- Completely mechanical gear-driven design – no power required
- Extremely reliable, used for decades in harsh environments
- Now discontinued and spare parts no longer available
- Unique round panel cut-out makes replacement difficult with modern timers
2️⃣ Introducing the BCT2 (240V Digital Timer)
The BCT2 is Bolec’s recommended replacement model for ISGUS timers.
With the conversion disc supplied in the kit, it can be installed directly into the existing ISGUS panel hole without modification.
- Supply voltage: 240V AC (1 = +, 2 = −)
- Output contacts: SPDT (3 = N/C, 4 = COM, 5 = N/O)
- Time range: up to 24 hours (fully adjustable)
💡 Advantages of Upgrading to Digital
- Better vibration resistance – solid-state and relay-based design
- LED indication for clear ON/OFF visibility
- Easy to source and replace – current production model
- Conversion disc allows re-use of the existing ISGUS panel
3️⃣ Pin Configuration Comparison
| Function | ISGUS Terminal | BCT2 Terminal | Description |
|---|---|---|---|
| Power + | N/A (mechanical) | 1 (+) | Timer internal supply (L) |
| Power − | N/A (mechanical) | 2 (−) | Timer internal supply (N) |
| Common (COM) | 1 | 4 (COM) | Relay common terminal |
| Normally Closed (N/C) | 3 | 3 (N/C) | Closed when timer is OFF |
| Normally Open (N/O) | 5 | 5 (N/O) | Closed when timer is ON |
4️⃣ Installation Steps (Conversion Kit)
- Switch off all power and verify isolation.
- Note or photograph the existing ISGUS wiring (terminals 1, 3, 5).
- Remove the ISGUS timer from the panel (approx. Ø60 mm round hole).
- Fit the conversion disc into the same opening.
- Mount the BCT2 securely in the centre of the disc.
- Reconnect wiring according to the pin configuration above.
- Power on and test with a short timing cycle.
During testing: 4→5 closes when timer is ON, and 4→3 closes when timer is OFF.
5️⃣ Comparison Summary
| Feature | ISGUS (Old) | BCT2 (New) |
|---|---|---|
| Design | Mechanical gear-driven | Electronic / digital control |
| Power | Not required | 240V AC (1–2 terminals) |
| Visibility | Dial only | LED indication |
| Vibration Resistance | Mechanical wear possible | Stable relay design |
| Spare Parts | Obsolete | Readily available |
| Mounting | Unique round hole | Fits via conversion disc |
With the Bolec BCT2 Conversion Kit, you can modernise existing ISGUS installations, maintaining the original panel layout while upgrading to a more reliable, digital solution.