To power a 20m COB LED strip reliably, first confirm its rated voltage and power consumption per metre, then calculate the total load and current. Do not assume that one power connection at the start will provide even brightness along the entire run: voltage drop can make the far end dimmer, especially with low-voltage strips. Depending on the strip’s specifications and installation, a suitable design may use power injection at multiple points or separate parallel sections supplied from one correctly rated power supply. The right layout must be confirmed against the product datasheet, cable length, and installation conditions.
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This guide explains how to plan a continuous-looking indoor installation without guessing at electrical requirements. We cover the calculations, connection options, common mistakes, and details to share with a supplier before ordering. Because COB LED strips vary, the examples below are illustrative calculations, not specifications for every 20m product.
A 20m run creates a larger electrical load than a short sample of the same strip. The current drawn depends on both the strip’s wattage per metre and its operating voltage, so length alone does not determine the required power supply. As current travels through the copper conductors in the strip and supply cable, resistance causes voltage drop. If the voltage at the strip is too low, light output or colour consistency may vary along the run.
“Continuous run” can mean a visually uninterrupted line, but it does not always mean that all 20m should be powered through one end-to-end electrical connection. A system may look continuous while using concealed feed wires or multiple parallel power connections. Confirm whether the strip is approved for a 20m feed from one end; if the datasheet does not state this, ask the manufacturer rather than assuming.
Use the following formulas as a starting point: Total strip power (W) = watts per metre × 20m, and current (A) = total power (W) ÷ voltage (V). For example, if a hypothetical strip is rated at 10W/m, a 20m installation has a calculated load of 200W. At 24V, that example draws about 8.33A; at 12V, the same 200W load draws about 16.67A.
These figures are examples only and should not be treated as the rating of a particular COB strip. Use the exact wattage and voltage shown on the product documentation, and account for any project-specific operating conditions. A power supply must match the strip’s voltage and provide sufficient output capacity for the calculated load; confirm the appropriate reserve with the supplier or the power-supply manufacturer.
Before selecting a power supply, record the strip’s rated voltage, watts per metre, colour type, cut intervals, and maximum recommended run length. Check whether the strip is single-colour, tunable white, or addressable, because control equipment and wiring requirements can differ. Also confirm whether the installation is in an aluminium profile, a cabinet, a ceiling detail, or another location, since mounting and heat management affect the installation plan.
Multiply the rated watts per metre by the installed length, using the actual length if it differs from 20m. Then divide the resulting wattage by the rated voltage to estimate the current. Share both calculations with the supplier so the strip, power supply, dimmer or controller, connectors, and conductors can be checked as a complete system.
For some products and layouts, a single-end feed may be acceptable, but only if the manufacturer’s guidance supports the full run length and expected load. If the strip’s permitted run length is shorter than 20m, a common design approach is to divide the run into shorter sections and feed those sections in parallel from the supply or distribution point. Another option may be power injection at multiple points along the physical run, provided the wiring and connections are designed for the product.
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Parallel feeding means each section receives power from the supply distribution rather than relying on current passing through every preceding section of strip. The visible line can still be continuous if joints and feed wires are concealed appropriately. Do not connect the output of separate power supplies together unless the equipment documentation specifically permits that configuration.
Choose cable gauge and length based on current, distance, installation method, and applicable electrical requirements. Long supply wires can also cause voltage drop, so a layout with a suitably located power supply or distribution point may perform better than a long, undersized feed. Confirm that connectors, dimmers, controllers, and terminals are rated for the voltage and current they will carry.
Keep the power supply accessible for inspection and replacement, and provide ventilation as required by its documentation. The LED strip operates at low voltage, but the power supply connects to mains electricity. Mains wiring should be completed by a qualified professional in accordance with local electrical codes.
Test the full run before fitting covers or closing ceilings and joinery. Check brightness and colour consistency at the beginning, middle, and end, and verify the system under its intended control settings. If the far end appears dimmer, investigate feed location, cable size, connection quality, and the strip’s maximum run guidance before accepting the installation.
| Decision | What to confirm |
|---|---|
| Strip voltage | Match the power supply output to the strip’s specified voltage. |
| Power per metre | Use the datasheet value to calculate the total 20m load. |
| Maximum run length | Confirm whether the product permits one-end feeding over the planned length. |
| Feed layout | Choose a single feed, multiple injection points, or parallel sections according to product guidance. |
| Controls and accessories | Check compatibility and current ratings for dimmers, controllers, cables, and connectors. |
Plan the power supply and feed points alongside the lighting layout, rather than treating wiring as a final detail. If the product documentation does not confirm a 20m single-feed run, ask for a recommended feed diagram before installation. For a visually continuous line, coordinate feed-wire routes and section boundaries with the profile, cabinet, or ceiling design.
When comparing options, evaluate more than the COB appearance. Review rated voltage, power per metre, colour and dimming requirements, cut interval, maximum run guidance, and compatibility with the proposed control system. Request the relevant product datasheet and a written recommendation for the intended length and feed arrangement.
At ENTA Lighting, we recommend sharing the intended 20m layout before confirming a COB LED strip selection. Provide the strip voltage you require, target brightness or power range, colour specification, dimming method, installation location, and approximate cable distances. With these details, we can help review product options and identify the information needed to confirm a suitable power and connection plan.
For a project quotation, include the quantity, destination market, required delivery schedule, and whether you need the strip, power supplies, profiles, or control components. We can then discuss the product documentation and configuration relevant to your application. Final electrical sizing and mains installation should be verified by the responsible project electrician.
A 20m COB LED strip can create a continuous indoor lighting line, but reliable operation depends on its actual voltage, wattage per metre, maximum run guidance, and feed arrangement. Calculate the full load first, then confirm whether the strip needs multiple power feeds or parallel sections instead of relying on a single end connection. Before ordering, send the supplier your strip requirements and installation layout, and verify the final design against the product documentation and local electrical requirements.
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