Float switch
A float switch is a simple, reliable level sensor that turns a pump on or off automatically as the water level rises or falls. It floats on the surface of the water and tilts as the level changes, opening or closing an internal switch at a set high and low point. That one action does two jobs at once: it stops a tank from overflowing, and it protects the pump from running dry. Waves Fluid Engineering Pte Ltd is the Singapore distributor for Nolta float switches, made in Germany, so we can supply, install and replace them at the best price.
Also known as: liquid level switch, water level switch, cable float switch, tethered float switch, level regulator, level controller and pump float switch. All describe the same tilt-activated level sensor.
How a float switch works
Every float switch works on the same tilt principle. As the water moves it, the internal contact opens or closes and the pump responds:
1
Float rises with the water
As the level climbs, the tethered float lifts and tilts past its switching angle.
2
Switch changes state
The tilt opens or closes the internal contact, which starts or stops the pump (or triggers an alarm).
3
Level held in range
The pump runs only between the set high and low points, so the tank never overflows and the pump never runs dry.
Draining duty vs filling duty
The same float switch can do two opposite jobs depending on how it is wired. Getting this right is the whole point of the installation, and it is where most DIY set-ups go wrong:
Emptying / drainage
Draining duty (dry-run protection)
Used in sump pits and drainage. The pump runs when the water is high and stops when it drops to the low point.
- Pump ON at high level, OFF at low level
- Protects the pump from running dry
Filling / overflow
Filling duty (overflow protection)
Used to fill storage and roof tanks. The pump runs when the water is low and stops when the tank is full.
- Pump ON at low level, OFF at high level
- Stops the tank from overflowing
The switching direction is set by which cable cores are connected, and a changeover model can be wired either way. Our team wires the float to the correct duty for your tank and pump so it behaves exactly as intended.
Pump-duty vs control-duty switches
Float switches come in two electrical grades, and choosing the wrong one is a common cause of burnt contacts:
- Pump-duty (direct control): carries the pump's full load current and switches the pump directly, with no relay needed. Nolta's N1 pro is a pump switch for this duty.
- Control-duty (signal): carries a low signal current into a control panel or contactor, which then switches the pump. Used where a panel already handles the load.
We check your pump rating and control panel and supply the correct grade, so the float is never asked to switch more current than it is rated for.
Nolta float switch range we supply
Nolta level regulators are built in Germany with sealed polypropylene housings, IP68 protection to 2 bar and chemically resistant cable, which is why they hold up in tanks, sumps and waste water for years. We recommend the model based on your medium, the space in the tank and whether it is switching a pump directly or signalling a panel.
Nolta N1 pro
Pump dutyproResist cable, NO / NC
- DutyDirect pump control
- Breaking cap.10(8)A / 250V
- ProtectionIP68 / 2 bar
Nolta MS1
Waste waterSingle-point level control
- Best forSewage & solids
- Cable5 to 20 m
- ProtectionIP68 / 2 bar
Nolta M2
CompactSmall-space level control
- Best forNarrow shafts
- Switchingup to 2A / 250V
- ProtectionIP68 / 2 bar
Cable options and NO / NC versions are available across the range, with cable lengths cut to suit your tank depth. Other Nolta level regulators and accessories (contactor combinations, motor starters) can be supplied on request.
Key specifications
Typical characteristics of the Nolta float switches we supply. Exact figures vary by model and are confirmed on quotation.
| Specification | Detail |
|---|---|
| Housing | Sealed polypropylene (PP), chemically resistant |
| Protection class | IP68, watertight to 2 bar for continuous submersion |
| Switching function | Draining, filling or changeover, plus high / low-level alarm |
| Contact type | Normally open (NO) or normally closed (NC) versions |
| Cable | Chemically resistant, cut to length (typically 5 to 20 m) |
| Max. temperature | Up to about 80 to 85°C depending on model |
| Media | Clean water, sewage, waste water and many aggressive liquids (model dependent) |
Where float switches are used
- Fill control for roof, transfer and storage water tanks
- Dry-run protection for booster, transfer and sump pumps
- Sump pits, basements and drainage, keeping them from flooding
- Sewage and waste water pumping stations
- High-water and low-water alarm signals to a control panel or BMS
- Condominiums, industrial buildings, factories and commercial premises
Recent supplies
How Waves Fluid Engineering helps
- Supply of genuine Nolta float switches at distributor pricing, with the right cable length
- Installation and correct wiring for draining or filling duty, tested on site
- Replacement of faulty or worn float switches on existing pumps and tanks
- Advice on the right model and grade for your pump rating, tank and medium
Our certifications
BCA ME11
Mechanical Engineering, L1
BCA GB1
General Builder Class 1
bizSAFE Star
Workplace Safety & Health
ISO 9001:2015
Quality Management System
Warranty
One-year warranty on float switches we install
We supply only genuine Nolta parts from a globally recognised manufacturer and provide a one-year warranty on float switches installed by Waves Fluid Engineering Pte Ltd at your premises (subject to terms and conditions).
Related products & systems
Leak detector control panel
Holding tank SMS alert system
Sump pump system
Transfer pump system
Reflex pressure tanks
Pump maintenance works
Frequently asked questions
What is a float switch used for?
A float switch turns a pump on or off automatically based on the water level. It keeps a tank from overflowing and protects the pump from running dry, which is the most common cause of pump burnout. It can also be used to send a high-water or low-water alarm signal to a control panel.
How does a float switch work?
The float sits on the water surface and tilts as the level rises and falls. When it tilts past its switching angle, an internal contact opens or closes, which starts or stops the pump. The pump then runs only between the set high and low points.
What is the difference between draining and filling duty?
In draining duty (sumps and drainage) the pump runs when the water is high and stops when it is low, protecting the pump from dry running. In filling duty (storage and roof tanks) the pump runs when the water is low and stops when the tank is full, preventing overflow. The same float does either job depending on how the cable cores are wired, and a changeover model can do both.
Which Nolta float switch do I need?
It depends on the medium and the duty. The N1 pro is a pump-duty switch that can control a pump directly. The MS1 suits waste water with dissolved solids. The M2 is a compact switch for narrow shafts and small tanks. We recommend the right model after checking your tank, pump rating and liquid.
What does NO and NC mean on a float switch?
NO (normally open) and NC (normally closed) describe the resting state of the internal contact when the float is hanging down. Choosing NO or NC, together with the cable cores used, sets whether the switch turns the pump on or off as the level rises. We supply the correct version for your application.
Can a float switch control a pump directly, or do I need a panel?
A pump-duty float such as the N1 pro can switch a pump directly, with no relay, as long as the pump is within the float's rated current. For larger pumps, or where a control panel already handles the load, a control-duty float sends a low-current signal to the panel or contactor instead. We match the grade to your pump.
Are Nolta float switches suitable for sewage and waste water?
Yes. Models like the MS1 have a chemically balanced, sealed PP housing that resists sewage, slurry and many emulsions, and are rated IP68 for continuous submersion. This makes them reliable in waste water pumping stations and sump pits.
Do you install and replace float switches?
Yes. We supply, install and wire new float switches to the correct duty, test them on site, and replace faulty or worn float switches on existing pumps and tanks anywhere in Singapore.
Need a float switch supplied or replaced?
Call or WhatsApp +65 9487 0446 or email sales@wavesfluid.com.sg for pricing and advice on the right model.
