Before you add more pixels, draw the power path. We want to know how power gets from the supply, through the protection and cables, to the last pixel. That is what makes a useful plan.
A bigger supply is only part of the answer. The output, fuse, connector and cable still have their own limits. Work through those limits before ordering parts or extending an existing run.
Start with the pixels you actually own
Write down the product and variant, voltage, count per output, wire size, extension length, connector and controller limits. Similar-looking strings do not necessarily draw the same current or use the same voltage.
Our EVO pixels are a 12V WS2811 product. EVO+ uses a different pixel design. Use the requirements for the one you are installing. A current rule copied from a generic 5V pixel tutorial is not automatically an EVO or EVO+ specification.
For a supplied lighting system such as Kraken Flex, include its actual strand arrangement and connection requirements in the plan. Do not assume the power arrangement from another product carries over.
Separate amps from watts
Once you have a suitable current figure for the exact pixel and operating condition, use these calculations:
- Amps = pixel count × milliamps per pixel ÷ 1,000.
- Watts = supply voltage × amps.
Here is a deliberately hypothetical example: 400 pixels at 12V, each using 20mA under the chosen design condition. These are not EVO, EVO+, Kraken or controller ratings.
| Calculation | What it gives you |
|---|---|
| 400 × 20mA ÷ 1,000 | 8A for the pixels |
| 12V × 8A | 96W for the pixels |
| 100 × 20mA ÷ 1,000 | 2A for a 100-pixel group |
Add the controller and any other loads separately. Then check whether each branch can carry its share. The arithmetic does not tell you that a particular output can supply 8A or that a given extension can carry 2A over any distance.
Adafruit's power guide is useful background on why patterns and pixel designs affect current. Apply the method with your own product's figures.
Check every part of the path
Add the loads sharing each supply and follow its operating-margin, temperature and ventilation instructions. The maximum number on the label is not the available output under every condition. MEAN WELL's guidance explains temperature-related derating.
Now work downstream: distribution, protection, controller bank, output, connector, extension and string. The lowest applicable limit matters. Replacing the supply with a larger one does not increase the rating of everything attached to it.
Understand what the cable costs you
Wire and connections have resistance. Current through that resistance reduces the voltage at the load. Include both the positive and return conductors when evaluating the complete current path.
The relationship is voltage drop = current × resistance. A hypothetical 0.20-ohm loop carrying 4A drops 0.8V. Starting at 12.0V gives approximately 11.2V at the load before other losses. Whether that is acceptable depends on the particular pixel's permitted range.
Long extensions, small conductors, poor connections and heavier loads can increase the problem. Dim pixels or unexpected colors can be clues, but those symptoms alone do not prove voltage drop. Compare the actual installation with the power-distribution principles.
Plan injection before connecting another feed
Power injection supplies an additional point on a prop or string. Decide where the feed comes from, what protects it and how it connects. Match conductor size, connectors and branch protection to the intended load and length, with suitable protection near the source according to the equipment instructions.
Do not tie ordinary independent supplies' positive outputs together unless that equipment is expressly designed for parallel operation. A multi-supply layout needs properly separated positive sections and the correct data ground reference. The WLED wiring guide explains the arrangement.
If that separation is unclear, send us a diagram before wiring it. Injection also does not add data ports or expand the controller's addressable pixel limit.
Choose a brightness, then verify it
View the lights from where your audience will stand and choose a suitable brightness. Verify the actual load at that setting. A 30% slider does not guarantee exactly 30% of maximum current across every pixel design and effect.
Software features such as WLED's brightness limiter estimate load using configured assumptions. They do not replace correctly selected wire, connectors or fuses. Record where your limit is applied and check test modes too; a restored or replacement controller may have different settings.
Test and keep the numbers with the prop
Test the intended patterns within the system's design limits. Watch for dimming, unstable colors, warm connections and protection trips. Where suitable low-voltage test points exist, a properly used meter can compare the source and load while operating. Disconnect power before changing wiring.
Keep a record of each branch's prop, count, voltage, expected load, cable length, wire size, protection and brightness. Recheck it when you move the controller or add pixels.
Need help reviewing the plan? Send Mattos support the actual product names and a simple wiring sketch. It is easier to choose the right connection before the display is in the yard.
Build a power-route record you can use outside
Give each physical branch its own row. This is the handoff between the calculations and the installation; a grand total for the whole show cannot tell you which extension or connector is carrying the load.
Scroll sideways to see all columns.
| Branch | Record the intended setup | Record the observed result |
|---|---|---|
| Window left | Exact pixel variant, occupied node positions, source/output, extension length and protection. | Test pattern/brightness, actual source and load voltage where safely measurable, and any unstable behavior. |
| Window right | Its own route and count, even if it looks identical in the preview. | The same repeatable test, using that installed route. |
| Coro character | Matching model, pixel path and any separately protected power feeds. | Color/chase results plus the verified load used for the design. |
Keep power troubleshooting and data troubleshooting distinct. If a prop passes a controller-local test but not the sequence, check configuration and addressing. If it passes with a short lead but fails through the intended extension, investigate both voltage at the load and the data path. A symptom by itself does not identify which one failed.
After a change, repeat the test that originally passed. Replacing a supply, extending a cable, increasing brightness or adding nodes changes an assumption in the original plan. Record the new result and date instead of relying on last year's notes.
Use the layout-to-parts-list worksheet to keep this electrical record alongside the shopping list, and check the connector path before ordering additional feeds or adapters.
