LED Project Design Guide - Wires & Connectors
Wiring and Connectors:
An often over looked component for a project, the wires and connectors used to put everything together is equally important as the other project components. Under rated wires or connectors can cause power distribution issues which can result in inconsistent color between LEDs or pixels. Proper power distribution and routing can greatly affect the quality of the project.
Power Wiring: As a general rule, use the heaviest gauge wire that is reasonable for the project, especially on the main power runs, such as from the PSU to the LEDs. If there is a long wire run between LEDs or from the power supply, those are the areas that should have the thickest wire. Thicker wire results in a lower resistance for the wire run, voltage levels will drop as it is transmitted through wires, thicker wire has less resistance so therefore less voltage drop. Bad power routing causes LEDs and pixels to be dimmer than expected. It is especially noticeable when a long pixel strand is powered, the end(s) closest to the power supply will be at full intensity, while the pixels further down the strand and further away from the power supply are noticeably dimmer, affecting the color consistency. It is very noticeable on certain projects and must be avoided. The best method is to inject power into the pixel strand as often as possible, these injection points are a direct connection to the power supply or power distribution point with heavy gauge wire. Supplying numerous power 'injections' can be difficult, NLED has a few products to make power injection easier. Products Webpage
Data Wiring: For addressable pixels, some require one wire for data(WS2812) and others require two wires for data(WS2801). This wire should not be overly thick, as it can cause data stability issues. Typically 22-28 AWG is suitable.
Data Wiring, Long Distance: Note that addressable pixels have a maximum distance between pixels before data stability issues(like noise or cross talk) become a big issue, usually resulting in flickering/strobing of the pixels. Reference the datasheets for specifics for your pixels, commonly 3 to 5 meters is specified. Some solutions for long distance signal stability are to run each data signal wire as a twisted pair, the data wire with a GND/common wire. If the chipset has 2 data wires(clock and data), run a separate twisted pair for each signal. For very long distance communication the signal can be converted to differential signals and transmitted very far distances. www.nledshop.com/miscproducts/
Connectors: A common bottle neck and often not considered. All connectors, whether it is wire-to-board or wire-to-wire have limits on how much current they can pass through before negative effects such as heating and voltage drop become an issue. If an under-rated connector is used, it can cause issues like lower voltage and limited current draw, which can dim LEDs or make them not function at all. Voltage ratings are less important as they are usually a few hundred volts, not an issue with low voltage DC. The actual current ratings of connectors is specified by the manufacturer.
Connector Ratings: The common JST(-SM) connectors commonly used for LED pixels are rated for 3 amps, which equates to about 50 RGB pixels. Common tube jacks(2.1x5.5mm or similar) have ratings between 2 amps and 5 amps. For high current applications, like power supply connection and long runs, connectors like XT-30(30 Amps) or XT-60(60 Amps) with heavy wire are recommended.
Notes:
The barrel jack adapters with screw terminals that are commonly sold with LED strips and pixels are very under-powered, and should not be used for more than 1-2 amps worth of LEDs.
Clip on jumpers for LED strips are also under powered and shouldn't be relied upon for much current consumption.