The EGO 500 SELS is an automatic puddle pump that uses electronic water-sensing probes rather than a traditional float switch. It is part of the EGO 500 Range of water pumps, which also include the EGO 500 GI and EGO 500 GI LS. If you need a floor-sensor automatic with fixed switching levels instead, see the Stream SPP2-4A and SPK530A.
This allows reliable low level automatic operation in shallow sumps or tight chambers, the kind of places where a mechanical float can jam or stick, or simply will not let the pump draw the water down as low as you need. If you are new to this style of pump, our guide to what a puddle pump is explains the basics, and our overview of automatic water pumps and the different switches compares sensors with float switches.
How the sensor system works
The SELS detects water by sensing electrical conductivity. Three stainless steel probes are mounted on a vertical rail:
- Probe 1, brown, common reference. This does not set a water level by itself. It provides the electrical reference the control card uses to detect when water has reached the other probes.
- Probe 2, black, stop level. When the water falls to this probe, the pump prepares to switch off.
- Probe 3, blue, start level. When water rises to this probe, the pump switches on.
The control unit applies a small sensing voltage between the common reference probe and one of the level probes. Water conducts electricity slightly, so when water touches both probes it completes a tiny circuit. The control unit reads that circuit and knows water is present at that level. Because there is no moving float, there is nothing to snag or stick, which is the main reason this system works so well in narrow chambers.
Factory settings
From the factory, the EGO 500 SELS is typically set to:
- Turn on at approximately 125mm water depth
- Turn off at approximately 40mm water depth
In normal use, water reaching the start probe turns the pump on. When the level falls to the stop probe the pump turns off, with a short run-on period that finishes clearing the water and prevents repeated on and off switching. These factory levels suit most general drainage, but the real strength of the SELS is that you can adjust them.
Adjusting the sensors step by step
Each probe holder can slide up or down the rail and lock in place with its fixing screw. To reset the levels:
- Isolate the pump from the power supply before handling the probes.
- Loosen the fixing screw on the holder you want to move.
- Slide the start probe (blue) to the height at which you want the pump to switch on. It is adjustable down to approximately 15mm.
- Slide the stop probe (black) to the height at which you want the pump to switch off. It is adjustable down to a few millimetres.
- Re-tighten each fixing screw so the holders cannot move in service.
- Restore power and test the pump through a full cycle, watching that it starts and stops where you expect.
The pump runs for a short while after the water drops below the off level, which is what enables low level pumping down to around a millimetre. To help prevent it running dry, set the off level no lower than 3mm to 5mm.
Match the settings to the chamber
It is important to consider the size of the chamber and the rate at which water flows in. If the chamber is very small and the levels are set too low, the pump can drain the area quickly and then cycle on and off in rapid succession. This short-cycling causes premature wear and can lead to failure. Because it results from unsuitable setup rather than a fault, that kind of failure would not be covered under warranty, so always match the level settings to the chamber size and the expected inflow.
Built for shallow, awkward spaces
The EGO 500 SELS is designed for exactly the situations where floats struggle. It has a 0.47kW motor and is constructed from thermoplastic with a 304 stainless steel motor casing, with a triple seal for strong resistance to wear. A top outlet design lets water cool the motor, and the pump can be run while only partially submerged. Built-in thermal protection with automatic reset guards the motor, and it is rated for continuous duty up to 35C. It is supplied with 10 metres of heavy duty rubber power cable, a non-return valve and a variable hose tail as standard. It is suited to clean or slightly polluted water, but it is not recommended for ponds or water features.
Benefits of the EGO 500 SELS
- No external float switch to snag
- Low level pumping down to around 1mm
- Clean operation in narrow chambers
- Fine control over start and stop levels
This is why the SELS is particularly well suited to puddle pumping behind flood barriers, basement sumps and temporary flood response setups. For a fixed basement installation you may also want to read our guide to the best automatic water pump for a flooded basement, or browse the full EGO 500 range.
Alternative options
If the EGO 500 SELS is not quite right for your site, these pumps do a similar job. The EGO 500 GI and EGO 500 GI LS are from the same range and can run manually or automatically, with the GI LS pumping down to 1mm. The Stream SPP2-4A and SPK530A are automatic puddle pumps with a floor sensor and fixed switching levels.
See the EGO 500 range, or if you would like help choosing the right low level pump, use the Pump Finder.
