4-pin M12 fixture connector to RJ12 controller port — 10ft, locking, grow-room rated.
The Matrix M12 to RJ12 Cable/B4 (10ft) is the dedicated adapter cable that connects the M12 fixture-side port on Matrix LED and Hybrid fixtures to an RJ12 controller input port, enabling full dimming, scheduling, and spectrum control through a compatible controller such as the Matrix MC5.
The Matrix M12 to RJ12 Cable/B4 is the physical link between the M12 port on a compatible Matrix LED or Hybrid fixture and the RJ12 control input on a lighting controller. Without this cable, the fixture operates only in basic on/off mode — no dimming, no spectrum scheduling, no far-red or UV channel control. With it seated and locked, the controller has a stable communication path to the fixture for full program execution.
The B4 designation refers to the 4-pin M12 connector configuration on the fixture end. This is distinct from the B3 variant (3-pin M12 to RJ11), so matching the correct cable to your fixture's connector type is required before ordering. The RJ12 end is a standard 6P6C plug compatible with RJ12 controller ports, including those found on the Matrix MC5.
The M12 connector on the fixture end uses a threaded twist-lock collar that seats mechanically rather than relying on friction alone. In a working grow room — where cables are occasionally pulled, equipment is repositioned, and humidity cycles are constant — a locking connector stays in place where a push-fit plug would work loose and drop the control signal mid-run.
The cable jacket and connector housings are built for continuous operation in high-humidity indoor cultivation environments. The RJ12 plug on the controller end is molded to standard 6P6C tolerances and seats cleanly into the RJ12 port of controllers designed for daisy-chain fixture communication. The 10ft run gives enough reach to route from fixture to controller or to the first fixture in a daisy-chain sequence without introducing unnecessary slack.
In a Matrix LED or Hybrid installation, this cable is typically used at the head of a control run — from the controller's RJ12 output port to the first fixture's M12 port, or wherever a transition from the RJ12 controller interface to the M12 fixture network is needed. From there, fixture-to-fixture connectivity is handled by M12 daisy chain cables (A3 or A4 configuration depending on the fixture's connector type).
The B4 cable is part of the broader Matrix M12 cable ecosystem, which also includes M12 daisy chain cables in A3 and A4 configurations, a B3 variant (M12 to RJ11), and 3-pin and 4-pin M12 extension cables. Each cable type addresses a specific connection point in the system. Using the correct cable at each point keeps the control network clean and eliminates interface mismatches that can introduce signal instability or prevent controller communication entirely.
This cable is a required component for any licensed cannabis or hemp operator running Matrix LED or Hybrid fixtures with a controller that uses an RJ12 output — and whose fixture uses the 4-pin M12 (B4) port. It is a commissioning-phase item: if it's missing or mismatched at installation, the controller cannot communicate with the fixture and the full feature set of the lighting system is unavailable.
It is also a practical spare part for commercial facilities running large-scale Matrix installations. A damaged or missing cable at a single fixture in a multi-light room takes that fixture off controlled operation for the duration of the run. Keeping a spare B4 on-site eliminates that risk. Operators expanding an existing Matrix installation will also need additional B4 cables if they are adding fixtures that require the controller-to-fixture head connection.
| SKU | 10-010704-381 |
| Brand | Matrix |
| Cable Length | 10 ft (approx. 3 m) |
| Fixture-Side Connector | M12, 4-pin, threaded twist-lock |
| Controller-Side Connector | RJ12 (6P6C) |
| Cable Type Designation | B4 |
| Compatible Fixture Interface | Matrix LED and Hybrid fixtures with M12 4-pin (B4) port |
| Compatible Controller Interface | RJ12 controller input port (e.g., Matrix MC5) |
| Construction | Industrial-grade jacket; moisture-resistant for grow room environments |
| Catalog Category | Accessories & Cables / Lighting & Cultivation |
The B3 cable has a 3-pin M12 connector on the fixture end and terminates in an RJ11 plug. The B4 has a 4-pin M12 connector on the fixture end and terminates in an RJ12 plug. These are not interchangeable — you need to match the cable to the specific M12 port type on your fixture. Check your fixture's connector pinout before ordering.
Yes. The Matrix Hybrid 1000W has no built-in dimming or spectrum adjustment. Without a controller connected via the appropriate M12-to-RJ12 cable, the fixture operates only in full-on or full-off mode. The B4 cable is the physical link that allows a controller such as the MC5 to communicate with the fixture and enable dimming, spectrum scheduling, UV, and far-red channel control.
The RJ12 end of the B4 cable is a standard 6P6C connector and will seat physically in any RJ12 port. However, Matrix fixtures use a proprietary control protocol. Full dimming, spectrum, and scheduling functions are confirmed with the Matrix MC5 controller. Compatibility with third-party controllers that use RJ12 ports will depend on whether those controllers support Matrix's control protocol — verify with the controller manufacturer before integrating.
Typically one B4 cable is used per control zone at the controller-to-first-fixture transition point. Fixture-to-fixture connections within the same zone use M12 daisy chain cables (A3 or A4), not B4 cables. If your installation has multiple control zones or multiple controller outputs feeding separate fixture chains, you will need one B4 per zone head connection.
For a commercial cultivation facility running Matrix fixtures on a controller network, keeping at least one spare B4 on-site is practical. A single failed or damaged cable at the controller-to-fixture transition point removes that fixture from controlled operation for the remainder of the photoperiod until the cable is replaced. The cost of a spare cable is negligible relative to the cost of an uncontrolled fixture run at a critical growth stage.
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