Product Overview
The B-4 is commonly found in low-voltage gate and access-control panels where a reliable 11-pin loop detector is needed but line-voltage detector power is not used. It performs the same basic vehicle-detection job as other Model B detectors, but the voltage version is different. In the field, this matters because a detector socket may look the same while the power pins are fed with a different voltage. The B-4 can support exit loop, safety loop, and vehicle presence applications when the relay output is wired to the correct controller input. If the existing detector is labeled fail-secure or has an S suffix, the replacement should be matched to that behavior instead of assuming a standard fail-safe detector is correct.
Compatible With
This detector may be used with the following applications when the original voltage, connector style, output logic, and control-board documentation match:
- Reno A&E B-4 low-voltage Model B loop detector installations.
- Select 12VDC, 24VDC, or 24VAC class detector sockets in compatible gate and access-control systems.
- Applications using a single loop with relay outputs for exit, safety, presence, or control logic.
- Fail-secure B-4 style applications when the original unit label and operator requirements match.
- Related references include B-4, B4, B-4-S, B4S, BX-4, AX-4, SKT-11, and 802-4.
Features and Specifications
| Manufacturer | Reno A&E |
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| Product Type | Model B low-voltage vehicle loop detector |
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| Part Number | B-4 / B4 |
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| Application | Low-voltage vehicle detection for gate, parking, and access control systems |
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| Input Power | 12/24V class Model B version - verify label |
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| Channels | 1 loop channel |
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| Outputs | Relay output family - verify fail-safe or fail-secure behavior |
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| Connector | 11-pin Amphenol-style rear connector |
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| Sensitivity | Eight sensitivity levels |
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| Loop Frequency | Selectable operating frequencies |
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| Notes | Uploaded name references fail secure; confirm original side label before replacement |
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Also Known As / Related Part Numbers
These numbers and search variations are related to this product family. They should not be treated as exact replacements unless the voltage, connector, and detector function are confirmed.
Technician Note
Loop detector problems are not always caused by the detector module. A damaged loop, wet splice, poor lead-in cable, wrong sensitivity setting, frequency interference, or a loop installed too close to moving gate steel can create false detection or missed vehicles. Match the detector first, then test the loop and operator input before returning the gate to service.
Before Ordering
- Match the detector input power to the original unit and operator control voltage: 12/24V class Model B version - verify label.
- Verify the connector style and pin layout before ordering: 11-pin Amphenol-style rear connector.
- Confirm the required output style for the operator input: Relay output family - verify fail-safe or fail-secure behavior.
- Check whether the original application uses presence, pulse-on-entry, pulse-on-exit, fail output, or safety/hold-open logic.
- Inspect loop wire, lead-in cable, splices, and pavement cuts before assuming the detector module is the only failed part.
Important Ordering Warnings
- Do not interchange 120VAC, 240VAC, and low-voltage detector models by appearance alone.
- Do not assume fail-safe and fail-secure versions are interchangeable.
- Confirm 11-pin socket detectors versus plug-in Molex style detectors before ordering.
- Check whether the application needs relay outputs or solid-state outputs.
Professional Advisory
Do not use a loop detector as a replacement for required monitored photo eyes, safety edges, or entrapment protection devices. For high-voltage detector power, damaged wiring, nuisance gate movement, or uncertain safety-device wiring, have the system checked by a qualified gate technician.
Product Questions and Answers
Is the B-4 a low-voltage detector?
Yes. B-4 is the low-voltage Model B version and should be matched to the original low-voltage detector supply.
What does fail-secure mean on this type of detector?
Fail-secure describes how the detector output behaves during certain fault or power conditions. Match this behavior to the original system design.
Can B-4 replace B-3 or B-8?
No. B-3 is 120VAC and B-8 is 240VAC. The voltage version must match the detector socket power.
Does this detector use an 11-pin connector?
Yes, it is associated with the Model B 11-pin Amphenol-style connector. Confirm the actual socket and wiring before ordering.
What should be tested before changing a B-4?
Test loop continuity, insulation, lead-in wiring, power at the socket, output wiring, and the operator input before replacing the detector.
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