SHT 8800 – Active sensor for analog inputs

The active water sensor with analogue voltage output for smart home, building management systems and controllers

The Schabus SHT 8800 is an active water sensor with the switching principle “analogue voltage”. It is supplied with an operating voltage and, when water or a conductive liquid is detected, outputs a voltage level of approximately 80–90 % of the operating voltage. In the dry state the output is 0 V.

This voltage is evaluated high-impedance by an analogue input, for example in smart-home systems, building management technology or controllers with analogue inputs. Two V4A stainless-steel contacts, the corrosion-resistant potting in Wepuran® and an aluminium-reinforced mounting hole for secure installation make it a robust floor sensor.

The SHT 8800 is intended for regularly dry environments with only occasional water occurrences. It is not suitable for direct connection to Schabus water detectors.

Detect water – as an analogue voltage signal

On contact with water the SHT 8800 generates a clear voltage increase that your system can evaluate continuously.

How the active sensor works

Active sensors such as the SHT 8800 have electronic internals and require an operating voltage.

• On contact with water the output voltage changes, for example from low to high
• Passive sensors, by contrast, work purely mechanically or conduct current directly on water contact
• As soon as water touches the V4A contacts, the output voltage rises to approx. 80–90 % of the operating voltage
• When the contacts dry again, the output falls back to 0 V
• The input must be high-impedance; the sensor should only have to supply minimal current – typical for TTL or CMOS logic
• Loading the output can damage the sensor or produce incorrect measured values

What is included in the box

The sensor is supplied with the material for mounting.

• SHT 8800 active water sensor
• Mounting material (1 screw, 1 wall plug)
• Operating instructions

How the SHT 8800 is constructed

The SHT 8800 is a compact, fully potted sensor with permanently connected supply cable.

Mounting and connection

Read the operating instructions carefully before mounting and commissioning.

Mounting the sensor

1. Securely screw the sensor with screw and wall plug through the integrated aluminium mounting hole.
2. Place the two V4A stainless-steel contacts at the lowest point to be monitored. A defined installation position is not required, as the sensor reacts directly to liquid contact.
3. If the cable is too short it can be extended to a maximum of 20 m, e.g. with LIYY cable 2 × 0.14 mm² (article 300780).

Connecting the sensor

1. Provide an operating voltage of 10 to 30 V DC (SELV/PELV). Connect the brown core to Ub (plus) and the green core to ground (0 V).
2. Connect the white core (output) to a high-impedance analogue input of your system.
3. Evaluate the signal: approx. 0 V means “dry”, approx. 80–90 % of the operating voltage means “wet”.

Which liquids does the sensor detect?

The SHT 8800 requires a conductive liquid, i.e. water with a sufficient number of free ions.

• Detects conductive liquids such as tap water, saline water or coolants
• Also detects liquids with low conductivity
• Desalinated or multiply distilled water as well as pure water without free ions cannot be reliably detected
• Non-conductive media such as oils are not detected
• The medium should have a density of at least 0.7 g/cm³ and a certain conductivity
• The output voltage is almost linear with the operating voltage and is somewhat higher with salt water than with tap water or distilled water

Manufacturer’s notes

• Read the operating instructions carefully before mounting and commissioning and keep them
• Do not open the device; it contains no parts that can be serviced by the user
• Packaging material is not a toy and must be kept away from children
• Operate only with operating voltage according to SELV/PELV
• Avoid moisture (splash or rain water), dust and direct sunlight on the device
• Clean only with a dry linen cloth; if heavily soiled, slightly dampened; no solvent-containing cleaning agents
• Intended for residential, commercial and industrial areas as well as small businesses
• The manufacturer accepts no liability for damage or losses resulting from the failure to output an alarm signal despite water-level changes
• The CE declaration is available for download on the manufacturer’s website

Warranty, guarantee and disposal

The device is covered by the statutory warranty of at least 2 years in the EU. The manufacturer Elektrotechnik Schabus additionally offers a 5-year guarantee that can be registered online. Repair and spare parts are available directly from the manufacturer. In the event of a defect please contact the manufacturer; within Germany you will receive a free returns label by e-mail.

The device does not belong in household waste. The crossed-out wheeled-bin symbol reminds you to use the take-back systems for waste electrical and electronic equipment (WEEE No. DE91394868).

Why the SHT 8800 is suitable

Areas of application

• Smart-home systems with analogue input, e.g. Loxone, Home Assistant, openHAB, ioBroker
• Building management systems and KNX building technology
• PLC and industrial controllers with analogue inputs, e.g. WAGO, Beckhoff, Siemens LOGO!
• Data centres and server rooms
• Technical rooms, heating and air-conditioning systems
• Leakage monitoring on the floor in regularly dry areas

The Schabus SHT 8800 delivers an analogue voltage on water contact – for systems that evaluate genuine analogue values.

Further active water sensors from Schabus

• SHT 8815 (Art. No. 200370) – active water sensor with switching principle “unipolar resistance” for digital inputs with internal pull-up/pull-down resistor
• SHT 8824 (Art. No. 200324) – active water sensor with switching principle “controlled constant-current sink” (4–20 mA)

Frequently asked questions