Compare cable float switches and electrode/conductivity level switches: how each works, cost, moving parts, dirty water and conductive vs non-conductive
Choosing between a cable float switch and an electrode (conductivity) level switch is one of the first decisions in any tank, sump or borehole control job. Both are inexpensive and both will happily destroy a pump if chosen wrongly. The difference comes down to the liquid, the number of level points you need, and how much moving parts and fouling you are willing to live with.
A cable float switch is purely mechanical: a moulded float rises and falls with the liquid, and at the trip angle it opens or closes a micro or reed contact. No external power is needed for the sensing itself, and the float switches whatever load its contacts are rated for.
An electrode level switch is electrical: it mounts one or more conductive rods at different heights and passes a small current through the liquid. When the liquid reaches a rod it completes the circuit, and the controller reports that level. It has no moving parts but it requires a conductive liquid and its own low-voltage supply.
| Factor | Cable float switch | Electrode / conductivity switch |
|---|---|---|
| Principle | Mechanical float, contact changeover | Conductivity between probes |
| Needs conductive liquid | No | Yes |
| Moving parts | Yes (float, contact) | None |
| Dirty water / sludge | Good, with oil-resistant jacket | Probes foul, need cleaning |
| Level points | One per float | Many per controller |
| Typical use | Sumps, pits, sewage, single-point on/off | Clean water tanks, boilers, multi-level |
Many panels use both: an electrode or float for normal control and a second, independent high-level float as a hard-wired alarm or backup, so a fouled probe cannot cause an overflow. This redundancy is cheap insurance on any unattended pump station.
ELEHPD supplies cable and magnetic float switches for single-point on/off control in clean and dirty water, with SPDT contacts rated for direct pump switching and IP68 sealing for continuous submersion.
No. An electrode (conductivity) switch needs the liquid to carry current between the probes, so it only works in conductive media such as tap water, most waste water and many acids. For oil, distilled water or other non-conductive liquids, use a float switch or a capacitive/ultrasonic sensor instead.
A float switch has a moving float and a mechanical or reed contact, so it wears with each cycle but tolerates sludge and debris. An electrode has no moving parts, but its probes foul with scale, grease or biofilm in dirty water and need cleaning or an AC (rather than DC) supply to limit electrolysis. For heavily contaminated sumps the float is usually the more reliable choice.
One electrode controller can read several probe rods at different heights to give multiple level points from a single head, whereas each float gives a single trip point and needs its own cable run. For multi-level tanks with clean water the electrode system is often the lower-cost and lower-cabling option.
Send the ratings, dimensions and quantities you are working to and we will confirm the closest match from the ELEHPD catalogue, the compliance documents available for it and the lead time. OEM branding, private model numbering and buyer-specific cartons are available on qualified volumes.