The Belimo 01CT-5QP01 is a passive cable temperature sensor with an NTC20k thermistor element in a 8" [200 mm] x 0.24" [6 mm] stainless steel probe on 6.5 ft [2 m] of shielded plenum-rated cable. It measures -13 to 167°F [-25 to 75°C] with ±0.35°F @ 77°F [±0.2°C @ 25°C] accuracy, as a duct sensor with a mounting flange or as an immersion sensor in a thermowell.
The 01CT-5QP01 reads 20,000 Ω at 77°F [25°C] and 70,200 Ω at 32°F [0°C], so it connects to a controller input set up for the NTC20k curve over a 2-wire, 22AWG bare copper, black-jacket cable. The sensor is rated IP67 and NEMA 4X.
- Controllers and BAS analog inputs configured for the NTC20k curve
- Duct air temperature with an A-22D-A03 or A-22D-A05 mounting flange
- Water temperature in pipes with an A-22P-A.. thermowell, fluid up to 167°F [75°C]
- Cable runs that call for plenum-rated cable
- Stationary heating, ventilation and air-conditioning systems
Key Features
NTC20k Passive Element
20,000 Ω at 77°F [25°C] with ±0.35°F @ 77°F [±0.2°C @ 25°C] accuracy and a 2-wire connection. Measuring current <0.5 mA @ 77°F [25°C].
8" [200 mm] Stainless Steel Probe
0.24" [6 mm] diameter stainless steel probe that fits 6 mm mounting flanges (A-22D-A..) and A-22P-A.. thermowells.
Shielded Plenum-Rated Cable
6.5 ft [2 m] of 1 pair shielded plenum cable, 22AWG bare copper, black jacket, rated -13...167°F [-25...75°C] and 300 V.
IP67 / NEMA 4X Protection
Degree of protection IP67 (IEC/EN) and NEMA 4X (NEMA/UL). Ambient humidity max. 95% RH, non-condensing.
Air Duct or Water Immersion
Duct mount with an A-22D-A.. mounting flange, or immerse in water with an A-22P-A.. thermowell. Fluid temperature -13...167°F [-25...75°C].
cULus Approval
cULus acc. to UL60730-1A/-2-9, CAN/CSA E60730-1/-2-9. Certified to IEC/EN 60730-1; UL power source Class 2 Supply.
ZOT Supply is an authorized distributor of Belimo products.
Technical Specifications
| Specification | Detail |
|---|---|
| Product Type | Cable temperature sensor, passive |
| Measured Value | Temperature |
| Application | Air, water |
| Intended Use | Stationary heating, ventilation and air-conditioning systems |
| Output Signal, Passive Temperature | NTC20k |
| Measuring Range | -13...167°F [-25...75°C] |
| Accuracy, Passive Temperature | ±0.35°F @ 77°F [±0.2°C @ 25°C] |
| Measuring Current | <0.5 mA @ 77°F [25°C] |
| Nominal Resistance | 20,000 Ω @ 77°F [25°C] |
| Resistance Formula Constant | 4262 |
| Time Constant (63%), Water Pipe | Typical 7 s with brass thermowell; typical 9 s with stainless steel thermowell (thermowell A-22P-A.. with thermal contact fluid) |
| Time Constant (63%), Air Duct | Typical 155 s @ 0 m/s; typical 35 s @ 3 m/s |
| Probe Length | 8" [200 mm] |
| Probe Diameter | 0.24" [6 mm] |
| Probe Material | Stainless steel |
| Electrical Connection | Cable 6.5 ft [2 m], 2-wire |
| Cable Specification | 1 pair shielded plenum cable, 22AWG bare copper, black jacket, -13...167°F [-25...75°C], 300 V |
| Mounting, Air | Mounting flange A-22D-A03 (plastic) or A-22D-A05 (brass), optional accessory |
| Mounting, Water | Thermowell A-22P-A.., 1/2" NPT, with thermal contact fluid |
| Ambient Temperature | -13...167°F [-25...75°C] |
| Fluid Temperature | -13...167°F [-25...75°C] |
| Ambient Humidity | Max. 95% RH, non-condensing |
| Degree of Protection IEC/EN | IP67 |
| Degree of Protection NEMA/UL | NEMA 4X |
| Protection Class IEC/EN | III, Protective Extra-Low Voltage (PELV) |
| Power Source UL | Class 2 Supply |
| Certification IEC/EN | IEC/EN 60730-1 |
| UL Approval | cULus acc. to UL60730-1A/-2-9, CAN/CSA E60730-1/-2-9 |
| Quality Standard | ISO 9001 |
| Type of Action | Type 1 |
| Rated Impulse Voltage Supply | 0.8 kV |
| Method of Mounting Control | Surface mounted |
| Pollution Degree | 3 |
| Weight | 0.18 lb [0.080 kg] |
| Warranty | 5 years |
| Manufacturer | Belimo |
| Manufacturer Part Number | 01CT-5QP01 |
NTC20k Resistance Characteristics
| Temperature | Resistance |
|---|---|
| -4°F [-20°C] | 221,300 Ω |
| 14°F [-10°C] | 122,470 Ω |
| 32°F [0°C] | 70,200 Ω |
| 50°F [10°C] | 41,560 Ω |
| 68°F [20°C] | 25,350 Ω |
| 77°F [25°C] | 20,000 Ω |
| 86°F [30°C] | 15,890 Ω |
| 104°F [40°C] | 10,210 Ω |
| 122°F [50°C] | 6,720 Ω |
| 140°F [60°C] | 4,520 Ω |
| 158°F [70°C] | 3,100 Ω |
Specifications verified October 22, 2026 against Belimo 01CT-5..01 Technical Data Sheet, en-us, 2024-01-10, Belimo Resistance Characteristics of Passive Temperature Sensors, 2023-10, and Belimo 01CT-.. Installation Instructions, 2018-02 (71957-00001.D).
Compatible Accessories
Mounting Flanges, Air Duct
Thermowells, Water
Installation Extras
Documentation
Frequently Asked Questions
What sensing element does the Belimo 01CT-5QP01 use?
The 01CT-5QP01 uses a passive NTC20k thermistor element with a nominal resistance of 20,000 Ω at 77°F [25°C] and an accuracy of ±0.35°F @ 77°F [±0.2°C @ 25°C]. Configure the controller input for the NTC20k curve.
What temperature range does the 01CT-5QP01 measure?
The measuring range is -13...167°F [-25...75°C]. Ambient temperature, fluid temperature and the plenum cable rating all cover the same -13...167°F [-25...75°C] range.
Is the 01CT-5QP01 an active or passive sensor?
Passive. The 01CT-5QP01 outputs a passive NTC20k temperature signal over a 2-wire cable connection. Because a 2-wire passive sensor self-heats, the current through it should not be higher than the specified measuring current (<0.5 mA @ 77°F [25°C]), or measurement accuracy is affected.
Can the 01CT-5QP01 measure water temperature in a pipe?
Yes. Install the probe in a Belimo A-22P-A.. thermowell (immersion sleeve) with thermal contact fluid, such as the A-22P-A44 syringe with thermal paste. A-22P-A.. thermowells have a 1/2" NPT connection. Fabricated stainless steel and fabricated brass thermowells come in 2", 4", 6", 8", 12" and 18" [50, 100, 150, 200, 300 and 450 mm] lengths; machined stainless steel thermowells come in 2", 4", 6" and 8" [50, 100, 150 and 200 mm] lengths. Typical time constant is 7 s with a brass thermowell and 9 s with a stainless steel thermowell, and fluid temperature is rated -13...167°F [-25...75°C].
How should the thermowell be oriented in the pipe?
On pipes DN 50 (2") and smaller, install the thermowell at a 45° angle or in a pipe elbow. On pipes DN 65 (2-1/2") and larger, install it at 90° to the pipe.
How do I mount the 01CT-5QP01 in an air duct?
Use a mounting flange for 6 mm sensor probes: A-22D-A03 (plastic, up to max. 248°F [120°C]) or A-22D-A05 (brass, up to max. 260°C). Fix the flange to the duct, insert the probe through it, then lock the probe by tightening the hex nut with a wrench (A-22D-A03) or the screw with a screwdriver (A-22D-A05). Typical time constant in the duct is 155 s at 0 m/s and 35 s at 3 m/s air velocity.
What resistance should the 01CT-5QP01 read at 32°F and 77°F?
70,200 Ω at 32°F [0°C] and 20,000 Ω at 77°F [25°C]. The resistance table on this page covers -4 to 158°F [-20 to 70°C]; the NTC20k resistance formula constant is 4262.
Does connecting cable length affect the 01CT-5QP01 reading?
Yes. With lengthy connecting cables, the cable resistance must be taken into account; it depends on the conductor cross section and adds an offset to the measurement. The lower the sensor impedance, the greater the effect of line resistance.
- Sensor Type:
- Probe Only
- Probe Length:
- 8 Inch
- Temperature Element:
- 20K Thermistor
- Lead Length:
- 6.5 Foot Plenum Rated Cable
- Enclosure:
- No Box
- Supported Protocols:
- None
- Humidity Element:
- None
- CO2 Element:
- None
- Setpoint:
- No Setpoint
- Override:
- No Override
- Display:
- No Display