Floodlights

When turned on, a floodlight projects a beam of light at full brightness until it hits an opaque block or reaches a maximum range. The default range is 64 blocks, although this can be increased up to a limit of 255 by changing the maxFloodlightRange configuration setting.

Light from a floodlight has the same properties as torchlight, so it will prevent mob spawning, promote plant growth, and so on. It is not sunlight, however, so it will not ignite skeletons or power solar panels.

Most floodlights require a redstone signal to turn them on. Some types also have an internal switch.

Orientation

Starting with version 1.7, floodlights can face in any direction. When placing a floodlight, the business end will point away from the face of the block that you click on, so you may need to place a temporary block to get it facing the right way.

Floodlight Types

Unpowered Floodlight

This is the simplest to use as it needs no power source, but it is the most expensive to make and requires materials from the Nether.

Carbide Floodlight

Runs on acetylene gas. Cheap to make, but must be supplied with fuel.

IC2 Electric Floodlight

Available when IndustrialCraft 2 is installed. Slightly more expensive than the carbide floodlight, but offers the convenience of electric power.

Limitations

Floodlights work by placing a line of invisible light-producing blocks along the beam path. Putting a transparent block, such as glass, directly in the path of the beam will prevent a light block from being placed there, and so the light intensity will be slightly reduced in the vicinity. However, this effect should not be noticeable unless you place a lot of transparent blocks in a row. Also note that if you fill the entire beam path (from the floodlight to the next opaque block) with transparent blocks, the floodlight will not produce any light at all.

In some situations, placing or removing blocks in a beam path may result in the beam not being updated properly. In most cases, you should be able to fix this by turning the floodlight off and on again. If that doesn't work, or if stray light blocks remain after removing a floodlight, you may need to force an update by temporarily placing a block next to the affected area.

The light blocks are designed to be as unobtrusive as possible, and will mostly behave the same way as air, but there is a possibility that they might interfere with the operation of other mods. There is one known issue in vanilla Minecraft: a large oak tree that grows near a floodlight will be left with a hole where the beam passes through. Other tree types are unaffected.

Turning a floodlight on or off causes a large number of lighting updates. As of version 1.11.2, floodlights have "slow" turn-on and turn-off characteristics, limiting the number of lighting updates that can occur per tick, so this should not normally be a problem. However, toggling a large number of floodlights simultaneously in a large open areas could cause momentary lag.