Introduction
Many legacy HPS lights, older LED grow lights, and even some of the latest non-waterproof LED lights from top brands use Registered Jack (RJ) style connectors for 0-10V dimming signaling. These connectors are convenient because RJ style splitters and cables are widely available and economical, however these connectors are not waterproof and may not offer the best reliability in a commercial setting.
There is no official industry standard around the use of these connectors or the specific connector to be used, and there is little information around compatibility across the various brands that use this style connector. This article breaks down all of your RJ connector questions.
1. What is the difference between RJ11, RJ12, RJ14, etc?
There are many different types of RJ style connectors. We'll focus only on the ones commonly used for dimming grow lights. Mechanically, all of these connectors can inter-mate, even though some have a different number of contacts and positions.
We have tested dozens of grow lights (LED, HPS, and CMH) over the last decade and haven't encountered one that needs all six wires. As a result, we have designed the RJ Adapter to mate to any grow light using one of the below RJ style connectors.
| RJ Type | Number of wires | Number of positions |
| RJ9 | 4 wires | 4 positions |
| RJ11 | 4 wires | 6 positions |
| RJ12 | 6 wires | 6 positions |
| RJ14 | 4 wires | 6 positions |
2. Which brands use RJ11, RJ12, or RJ14 connectors?
HPS lights that use RJ style connectors include Hydrofarm, Phantom, Dimlux, Luxx, Iluminar, and Gavita. In some cases, lights have been updated to remove the RJ connector and replace them with a sealed connector. Visually check your light for the connector type as the product documentation for many legacy lights is hard to obtain.
LED lighting brands that have used RJ style connectors at some point include Horticulture Lighting Group, Luxx, Mammoth Lighting, Spider Farmer, and Upowertek.
3. Which pins are used for dimming?
The pinout for a typical RJ9, RJ11, RJ12, or RJ14 connector is shown below along with the pin assignments. Note that there are two pins for dim+ and dim- respectively. We recommend always wiring all four positions, this way if only two positions are connected inside your light, you will still have a dimming connection.
3. How to daisy chain a dimming signal to multiple lights
We recommend using GrowFlux's daisy chain cables from our Universal Dimmer product family - this way most of your wiring will be waterproof, your installation will be future proof when you eventually upgrade your lights, and you will benefit from more robust cabling which uses UV resistant, UL rated 22AWG cables for runs up to 200 feet.
Alternatively, RJ style splitters and RJ cables can be used to daisy chain the signal to multiple lights (not available from GrowFlux). Keep in mind that some lights have an 'in' and 'out' RJ style connector, so you may not need to use splitters.