DLI Joule Series 1000w / 400v Grow Light Fixture
  • Dli 100 off
  • Dli angled 2
  • Dli angled rear
  • Dli front
  • Dli rear
  • Dli underside

DLI Joule Series 1000w / 400v Grow Light Fixture

SKU: 763200
£549.95 £424.95
DLI Joule Series 1000w / 400v Grow Light Fixture
  • Dli 100 off
  • Dli angled 2
  • Dli angled rear
  • Dli front
  • Dli rear
  • Dli underside

The Feature-Rich 1000w Lighting System that Delivers an Incredible Light Spread

The DLI (Dutch Lighting Innovations) Joule utilises a super-reflective, aluminium coated wide-angle reflector that delivers a phenomenal spread, distributing light evenly across the canopy (as even as anything else we've ever tested!). It's also low-profile, making it a better fit for your grow tent (or room) than some of the competition. It comes with a list of features, like a built-in spirit level to keep the light levels even around the canopy, maximising the productivity of your indoor garden. The DLI Joule is clearly very well thought out and represents a big step forward for 1000w lighting fixtures. Very highly recommended.

  • The culmination of decades of research by horticulturalists and engineers
  • Gets closer to your plants thanks to its wide-angle reflector
  • Built by Pepijn Looijaard and Ton ten Haaf, physicists and former engineers at Philips
  • Converts a 120-240V mains supply to run 400V lamps
  • Links up with the excellent DLM-4 Zone using RJ12 connectors
  • Includes all of the cables needed to wire it to the controller
  • Lower profile - better for those with limited headroom
  • No need to get a bigger tent, and much better for those in lofts
  • Built-in spirit level to ensure an even lighting footprint
  • Comes with a set of DLI gloves for changing lamps without leaving marks
  • Dimmable between 600w, 750w, 825w, 1000w and 1150w settings
  • Super-efficient heatsink design
  • Cool running for a 1000w light, with a ballast that feels cool to the touch
  • Allows heat to dissipate more freely, thanks to the open reflector


1 x DLI Joule 1000w lighting fixture, 1 x wide angle reflector, 1 x 1000w 400v lamp, 1 x 5m power cable with IEC connector, 1 x pair of DLI gloves, 2 x eyelet screws (to hang your light with), 2 x RJ12 cables (4ft and 16ft – for connecting to the controller), 1 x splitter (for connecting multiple fixtures to the controller)

Recommended Additional Purchases

DLM-4 Zone Controller

4-Way Powerbox (professional-grade power distribution system)

Rope Ratchets

How the DLI Joule Works:

The DLI Joule is built to high specifications – the second you pull it out of the box, you'll notice that it feels like a quality bit of kit. The Joule also comes with an array of impressive features and tweaks that make it stand out from the competition. For instance, the built-in spirit level ensures that the unit sits level once hung. It may not seem like a massive issue to the untrained user, but the systems's angle will impact on the footprint to quite a high degree – even more so the higher the light is away from the canopy, so it's crucial that you get it right.

The name suggests that it runs at 120V to 240V, but the Joule actually converts a standard residential mains supply to run 400V lamps, in the same way that you'd expect from a typical DE (double ended) lighting fixture. It pairs up nicely with the DLM-4 Zone Controller, and testing reveals that it delivers a phenomenal light-spread that will get the best out of a 1.5m x 1.5m grow space or a BudBox Pro GT1. This is due to the fact that it ships with a highly impressive wide-angle reflector that pushes light outwards instead of directing it downwards, allowing you to get your lighting closer to the top of the canopy without burning your plants. This maximises the effectiveness of every last µmol of light generated by the DE lamp. The process for making these reflectors is highly intensive. They are manufactured from a high-purity aluminium substrate coil which is electrochemically brightened. The material is then given an anodised base coat which minimises abrasion damage, and it is then treated using specially developed processes to maximise coating adhesion, finishing off with a layer of 99.99% pure aluminium for a reflective surface that's on a par with anything else out there (excuse the pun!).

You can switch between 600w, 750w, 825w, 1000w and 1150w settings using the dial on the underside of the unit; however, by running the DLI Joule with the DLM-4 controller, you can turn it up and down on a smooth gradient.

Unlike other comparable 1000w lighting fixtures, the Joule has been designed with a horizontally mounted ballast. This means that it's a much better fit for areas with limited headroom and you're less likely to need to invest in a 2.2m grow tent (as opposed to typical 2.0m models).


Technical Specifications

Input Voltage: 120 ~ 240V
Input Voltage Range: ± 10%
Rated Power: 1060W
Dimming with switch: 600W – 750W – 825W – 1000W – 1150W
Dimming with controller: 600W – 1150W
Frequency: 50/60 Hz
Typical Current: 4.5A @ 240V/1000W
Maximum Current: 9.5A @ 120V/1150W
Inrush Current: ≤ 40A
Power Factor:  ≥ 0,98
Dimensions: 571 x 284 x 178mm (22.5 x 11.2 x 7.0 inch)
Weight: 5.4 kg (11.9 lbs)

DLM-4 Zone

Testing reveals that it produces light that's very similar to other 1000w DE HPS lamps. It's incredibly high in the red areas of the spectrum, which we know delivers bigger fruits during the flowering stages, driving up yields. It also features low levels of light in the blue area of the spectrum, which helps to reduce stretching, keeping plants compact and making your garden more efficient. As with any HPS system, things can be improved further by adding supplementary lighting to further boost these areas. Check out our CDM lighting for more info.

DLI Joule-Series 1000w Lighting Footprint over a 2.01m x 1.5m Area at a height of 600mm:

DLI Light-Spread

The surface map above shows the ability of the reflector to project light onto the canopy, denoting the number of µmol measured at each given area. The DLI is actually quite exceptional: it's wide-angle reflector projects light outwards so well that we decided to extend the measurements to cover a wider area (1.5m x 2.1m, instead of the usual 1.5m x 1.5m area used for a typical 1000w lamp). The intensity is naturally heavier directly underneath the lamp, but we were, never the less, highly impressed by its coverage. Note that, if you run this system in 1.5m x 1.5m tent, you'll get a lot of light reflecting from the sidewalls, hitting plants from multiple angles. This will speed up growth rates and improve overall vigour when compared to lighting systems that simply hit plants from the top. Very highly recommended.

How to Use the DLI Joule:

Hang the unit in the required position in your grow room using Rope Ratchets. We recommend that it is hung at least 60cm above the canopy to get the very best from it. Next, connect up the 5m IEC power cable. If you're using it without a digital controller, you're going to need to plug it into a contactor and timer. If you're using it with a DLM-4 Zone controller unit, then the set-up process is a bit different. You can plug the DLI Joule straight into a wall socket (no contactor and timer needed), and regulate switching times via the controller. See the diagram below for more info on how to set this up. Note that all of the cables and splitters required are supplied with the units as standard, so there's no need to spend money on purchasing extras.

Warning 1: When it is time to change out the lamp, make sure that it is replaced with another 400 volt / 1000 watt double ended HPS lamp. To replace the lamp, first disconnect the power cable and make sure the unit has been off for long enough for the lamp to be cold to the touch. Slide out the black lamp holders at both ends of the lamp, this will release the lamp from its holder and allow it to be removed. You'll notice a little square tab inside the lamp (as shown in the image above). Make sure that this tab is located closest to the ballast and make sure that the wires at each end are kept straight and located snugly within the channels in the holders. Finally, slide the black lamp holder clips over the ends of the lamp to keep it in place.

Warning 2: When HID lamps are switched on they run extremely hot. As with all high pressure sodium and metal halide bulbs it is necessary to avoid touching the lamp with anything such as fingers or plants as this may cause severe burns or fires. In particular, avoid sprays or liquids coming into contact with the lamp as this may cause premature failure or even an explosion.

Please note:
Ensure that you follow manufacturer's guidelines when fitting your double ended lamp, as incorrect fitting will result in damage. This damage is NOT covered under the manufacturer's warranty.