Guide
Permanent lighting power & injection guide
Most visible quality problems in permanent lighting — dim far ends, whites that drift pink down the run — are power problems. This guide covers the two decisions that prevent them: sizing the supply, and injecting power where runs get long.
Sizing the power supply
Add up what the whole system draws, then buy headroom. A supply loafing below its ceiling runs cooler and lives longer than one working flat out. We stock the Mean Well LRS family at 350 W, 450 W and 600 W — one proven series, three sizes, each shipped as 12 V or 24 V to match your system. Our controllers ship configured with the supply chosen at order time.
Why long runs need injection
Low-voltage wiring loses a little voltage over every foot of run. On short runs nobody notices. On long runs, the lights furthest from the feed see less voltage than the first ones — and it shows as sagging brightness and whites drifting off-colour at the far end. The fix is not a bigger supply at one end; it is feeding power into the run again partway along: power injection.
How often to inject
Our recommendation for the systems we supply: on a 24 V system, plan power injection about every 50 ft of run; on 12 V, about every 30 ft. That difference is most of why we highly recommend the 24 V system — fewer injection points per roofline means less wiring, fewer connectors and a simpler install for the same finished look. Every Mean Well LRS supply we stock ships in your choice of either voltage at the same price.
Wiring an injection point
- Plan injection points by voltage — about every 50 ft of run on 24 V, about every 30 ft on 12 V.
- Tee into the run with a T connector — the run continues through; the stem takes the feed.
- Carry the feed with an extension cable back to the supply — long lengths (10–25 ft) exist mostly for this and for controller drops.
- Or fit a Power Injection Light — a puck built to accept the feed without breaking the light spacing.
Signal is a separate budget
Data fades over distance just as power does. If the controller sits far from the roofline, a data booster keeps the control signal clean — a $19.99 line that prevents a service call. Unsure whether a layout needs injection or boosting? Send us the plan; speccing runs is what our team does all day.