วิธีป้องกันแรงดันตกในการติดตั้งไฟ LED แบบยาว

In long-distance LED strip light installations, voltage drop is the core issue causing uneven brightness and shortened lifespan. As current in low-voltage LED strips (12V/24V) diminishes with increasing distance, voltage loss due to wire resistance significantly impacts lighting performance at the far end.

Without intervention, voltage drop may cause excessive brightness at the front section and dimness at the rear, potentially accelerating chip aging due to overcurrent. Additionally, voltage fluctuations can trigger chain reactions such as localized overheating or driver circuit failure.

Therefore, systematically addressing voltage drop requires a multi-dimensional approach encompassing power supply design, circuit optimization, and equipment selection to ensure stable operation of the LED strip lighting system.

What Is Voltage Drop?

Voltage drop in LED strips refers to the gradual decrease in voltage that occurs during operation due to resistance encountered by the current as it flows through components like LEDs and circuit boards. This phenomenon causes reduced brightness and uneven illumination across the strip.

In layman’s terms, it manifests as inconsistent brightness between the beginning and end of the strip—with the section near the power source appearing brighter while the trailing end noticeably dims.

Voltage drop not only affects the brightness and aesthetic appeal of LED strips but may also shorten their lifespan. Therefore, correctly understanding and addressing voltage drop issues is crucial for enhancing the performance of LED strips.

As shown below:When the input voltage to the LED strip is 12V, after traveling a distance of 5 meters, the voltage drops to 9.01V. This 3V difference represents the voltage drop.

The longer the LED strip, the greater the voltage drop. A voltage drop exceeding 5% may reduce the operating current of the LED chips, consequently diminishing their brightness.

Voltage drop is a physical quantity describing the ability of an electric field to move charge, also known as potential difference or voltage. When current flows through a conductor (such as wires or resistors), electrical energy is converted into heat due to the conductor’s resistance, causing a reduction in potential difference across its terminals.

การอ่านที่เกี่ยวข้อง: แรงดันตกที่แถบ LED: สาเหตุและแนวทางแก้ไข.

Causes of Voltage Drop in LED Strip Lights

Voltage drop in LED strip lights is a common issue affecting lighting uniformity, stemming from three core factors: input wire resistance loss, insufficient conductivity of PCB copper foil, and excessively low input voltage. Below we analyze these three aspects.

Wire Resistance

Wire resistance is a physical quantity measuring the degree of opposition encountered by current flowing through a conductor. It indicates the conductor’s ability to impede current flow and is measured in ohms (Ω). Its magnitude depends on the wire material, length, cross-sectional area, and temperature.

Metals like copper and aluminum have lower resistivity, while alloys and semiconductor materials exhibit higher resistivity. Longer wires exhibit greater resistance, while a larger cross-sectional area reduces resistance. Additionally, temperature increases can elevate resistance in certain materials (e.g., metals).

Ensure appropriately sized wiring is used between the power source and the light strip during operation. Thicker wires have lower resistance, meaning they transmit electricity more efficiently. Based on your power load (in watts) and wire length (in feet), you can use the table below to select the appropriate wire size for convenient voltage drop management.

12 Volt Voltage Drop Chart (5% Drop)
WIRE GAUGE	12 W	24 W	36 W	48 W	60 W	72 W	84 W	96 W	108 W	120 W
22 AWG	16 ft.	8 ft.	5 ft.	4f.	3 ft.	3 ft.	2 ft.	2 ft.	2 ft.	2 ft.
20 AWG	25 ft.	13 ft.	8 ft.	6 ft.	5 ft.	4 ft.	4 ft.	3 ft.	3 ft.	3 ft.
18 AWG	42 ft.	21 ft.	14 ft.	10 ft.	8 ft.	7 ft.	6 ft.	5 ft.	5 ft.	4 ft.
16 AWG	75 ft.	38 ft.	25 ft.	19 ft.	15 ft.	13 ft.	11 ft.	9 ft.	8 ft.	8 ft.
14 AWG	117 4.	58 ft.	39 ft.	29 ft.	23 ft.	19 ft.	17 ft.	15 ft.	13 ft.	12 ft.
12 AWG	183 ft.	92 ft.	61 ft.	46 ft.	37 ft.	31 ft.	26 ft.	23 ft.	20 ft.	18 ft.
10 AWG	275 ft.	138 ft.	92 ft.	69 ft.	55 ft.	46 ft.	39 ft.	34 ft.	31 ft.	28 ft.
24 Volt Voltage Drop Chart(5% Drop)
WIRE GAUGE	12 W	24 W	36 W	48 W	60 W	72 W	84 W	96 W	108 W	120 W
22 AWG	73 ft.	37 ft.	24 ft.	18 ft.	15 ft.	12 ft.	10 ft.	9 ft.	8 ft.	7 tt.
20 AWG	117 ft.	58 ft.	39 ft.	29 ft.	23 ft.	19 ft.	17 ft.	15 ft.	13 ft.	12 ft.
18 AWG	183 ft.	92 ft.	61 f+.	46 ft.	37 ft.	31 ft.	26 ft.	23 ft.	20 ft.	18 ft.
16 AWG	300 ft.	150 ft.	100 ft.	75 ft.	60 ft.	50 ft.	43 ft.	38 ft.	33 ft.	30 ft.
14 AWG	475 ft.	238 ft.	158 ft.	119 ft.	95 ft.	79 ft.	68 ft.	59 ft.	53 ft.	48 ft.
12 AWG	750 ft.	375 ft.	250 ft.	188 ft.	150 ft.	125 ft.	107 ft.	94 ft.	83 ft.	75 ft.
10 AWG	1092 ft.	546 ft.	364 ft.	273 ft.	218 ft.	182 ft.	156 ft.	136 ft.	121 ft.	109 ft.

Remark:

1. Calculate total load in watts.
2. Measure distance from power source to LED strip.
3. Select an appropriate wire gauge.

Minimize the operating length of the LED strip. The best approach is to power it from the middle section.

For example, suppose you need a 50-foot strip to illuminate a room. We recommend placing the power source in the middle and splitting the strip into two 25-foot sections running left and right, rather than one continuous 50-foot length. It doesn’t need to be split exactly in half—if more convenient, splitting into 20-foot and 30-foot sections is acceptable.

If placing the power source in the middle isn’t feasible, the second option is to run an appropriately sized wire (refer to the voltage drop chart) from the power source to the middle of the strip. This way, you maintain power at the start of the run while the properly sized wire (offering lower resistance than the LED strip itself) handles the heavy lifting.

Limitations on Copper Foil for LED Strips

While copper foil offers superior thermal conductivity compared to standard materials, it oxidizes easily in high-temperature environments, reducing heat dissipation efficiency. Prolonged operation at elevated temperatures may accelerate copper foil degradation, shortening the strip’s lifespan.

Copper foil is thin and brittle. External pressure or bending during installation or use may cause fractures, resulting in short circuits or non-functioning lights.

Additionally, copper foil corrodes easily in humid or high-temperature environments, requiring additional anti-oxidation treatments (such as nickel plating or silane coupling agent coating) to extend its lifespan.

Power Supply Voltage Levels (12V vs 24V vs 48V)

12V, 24V, and 48V LED strips exhibit significant differences in voltage drop impact and performance comparison:

• 12V strips experience noticeable line losses due to lower voltage and higher current. Brightness remains stable within 5 meters, but a significant voltage drop occurs beyond 5 meters, causing brightness decay at the tail end.

• 24V strips halve the current, reducing line losses and enabling voltage-drop-free transmission over 10 meters with superior brightness uniformity.

• 48V strips operate at lower currents—just 1/4 of 12V strips at equivalent power—minimizing voltage drop. They suit ultra-long-distance lighting (e.g., over 30 meters) but require a stable power supply.

‌At equal lengths, 24V strips typically deliver higher power and brightness than 12V strips. 48V strips, operating at higher voltage, can drive more LED chips for further brightness enhancement. High-voltage strips (24V/48V) consume less current and suffer lower line losses, making them more energy-efficient for long-term use.

‌12V strips require higher current, demanding greater heat dissipation and are prone to overheating in confined spaces. 24V/48V‌: Lower current reduces heat stress, but insulation protection in high-voltage environments must be ensured. 12V strips have lower initial costs, but extended lengths necessitate additional transformers or wiring, potentially increasing overall expenses.

12V vs 24V vs 48V LED Strip Performance Comparison

ประเภทแถบ LED	DC12V	DC24V	DC48V
ประจุบัน	ยิ่งกว่า	ลด	Lowest
Installation Distance	≤5m	≤10m	≤30m
มูลค่า	Increased power supply cost for long distances	Low cost	Relatively economical
Cut Length	Short distance	Medium distance	Relatively long distance
ความปลอดภัย	Low voltage, relatively safe	Safe	Lower safety, requires insulation precautions
การกระจายความร้อน	กระจอก	รสเด็ด	Fairly good

สรุป: Voltage selection requires balancing distance, brightness, cost, and safety. Opt for 12V for short-distance residential use, 24V for medium-to-long-distance commercial applications, and prioritize 48V for ultra-long distances or high-power projects.

Read the blog “เมื่อใดควรเลือกระบบแถบ LED 12V, 24V หรือ 48V? (ปรับปรุงเพื่อใช้ในเชิงพาณิชย์)” to learn more.

How to Calculate Voltage Drop?

Calculating the voltage drop of LED strips requires considering factors such as current, wire resistance, and length.

Basic Formula: Voltage Drop = Current × Wire Resistance

Where:

• Current (A) = Total Strip Power (W) ÷ Operating Voltage (V)
• Conductor Resistance (Ω) = Resistivity (copper wire: 0.0175 Ω·mm²/m) × Conductor Length (m) ÷ Conductor Cross-sectional Area (mm²)

ตัวอย่าง: 24V LED strip, 240W power, 40m conductor length, 4mm² wire gauge:

Current = 240 ÷ 24 = 10A

Resistance = 0.0175 × 40 ÷ 4 = 0.175Ω

Voltage Drop = 10A × 0.175Ω = 1.75V

In low-voltage systems (e.g., 12V/24V), voltage drop typically does not exceed 5% of the rated voltage (e.g., 24V systems allow ≤1.2V drop). If voltage drop exceeds specifications, increase wire gauge or shorten power supply distance.

Don’t want to deal with complicated calculations? Then use an online voltage drop calculator!

‌Wire Selection Recommendations: For long runs (>10 meters), prioritize 24V/48V systems to reduce current; Single-end power supply for 12V LED strips is recommended for ≤5 meters; 24V ≤10 meters; a dual-end power supply can extend to 20 meters.

Practical Testing: A multimeter can verify the voltage division effect of series resistors in LED circuits.

Practical Solutions to Prevent Voltage Drop

Voltage drop in LED strips caused by circuit resistance and current loss directly impacts lighting uniformity and lifespan. Below are several effective methods to prevent voltage drop.

Power Injection from Both Ends

Dual-End Power Supply: For longer strips, implement a dual-end power supply solution by connecting power sources to both the beginning and end of the strip. This ensures stable voltage supply across the entire strip, preventing uneven brightness. If feasible, add intermediate power points along the strip to further reduce voltage drop.

Multiple Power Injection Points

Segmented Control: Divide long LED strips into multiple sections, each powered by an independent driver. This approach effectively minimizes voltage drop per section while enhancing overall system stability and brightness uniformity.

Optimize Strip Layout and Connections: Ensure wiring is both functional and aesthetically pleasing, avoiding tangled or excessively bent cables. When connecting strips, guarantee secure, reliable contact to prevent additional resistance and voltage drops caused by loose or faulty connections.

Use 24V or 48V LED Strips

Employing 24V or 48V LED strips effectively mitigates voltage drop issues, exhibiting significantly less impact compared to 12V strips. While 12V strips experience noticeable brightness decay beyond 5 meters, 24V strips support lengths up to 10 meters without requiring additional power sources. Their flexible cutting points (every 6 LEDs) make them ideal for long-distance installations.

‌At equivalent power levels, 48V strips draw only half the current of 24V strips. Per the power loss formula Q=I²R, 48V systems exhibit significantly reduced thermal losses and lower voltage drop ratios. 48V systems allow more fixtures to be connected in series, reducing wiring and labor costs; 24V strips simplify installation by eliminating frequent power boosters. 24V strips generate less heat, making them suitable for extended operation; 48V systems further optimize energy efficiency.

Thicker Wires

Use thicker wires or reduce wire length: Wire resistance is a major factor causing voltage drop. Therefore, using thicker wires can reduce resistance and mitigate voltage drop issues. Additionally, minimizing the wire length between the strip and power source effectively reduces resistance and voltage drop.

Use Constant Current Solutions

Constant current LED strips fundamentally resolve voltage fluctuation-induced voltage drops inherent in constant voltage strips through precise current regulation.

Their core advantages manifest in three aspects: First, constant current circuits automatically adjust current flow. When line impedance increases or power supply voltage fluctuates, they maintain LED current stability at a set value (e.g., 20mA ±3%), ensuring consistent brightness from start to finish. Second, constant current prevents accelerated light decay caused by localized overheating in LEDs. Tests show LED lifespan extends by over 30% under constant-current drive.

Additionally, this solution exhibits low sensitivity to line resistance. Even with thin wires (e.g., 28 AWG) or long-distance wiring, dynamic voltage drop compensation dynamically adjusts to offset line losses. This design is particularly suited for scenarios requiring flexible wiring, such as long-distance decorative light strips, ensuring consistent LED strip brightness.

Use Amplifiers / Repeaters in RGB/RGBW Strip

During long-distance transmission of RGB/RGBW strips, signals degrade due to resistance and interference, causing uneven brightness or color distortion at the strip’s end. For 12V strips (typically ≤5 meters), amplifiers/repeaters enable stable control over longer distances (e.g., 30+ meters). High-voltage strips (e.g., 24V/48V) have lower current draw and reduced voltage drop, minimizing reliance on amplifiers/repeaters. When using 12V strips, install a repeater every 10 meters to compensate for voltage drop.

In summary, addressing LED strip voltage drop requires a multi-faceted approach, including improving power supply methods, optimizing wiring and layout, and utilizing auxiliary equipment. Users can select appropriate solutions based on specific conditions to enhance the performance and aesthetic appeal of their LED strip installations.

Recommendations for Designers & Buyers

As a core element of modern lighting design, LED strip lights’ voltage specifications—12V/24V/48V—directly impact project outcomes and user experience.

The 12V system excels in safety and flexibility, making it ideal for home decor. The 24V system strikes a balance between voltage drop and cutting convenience, becoming the mainstream choice for commercial settings. The 48V system, with its ultra-low line loss, is specifically engineered for large-scale illumination projects.

Designers should select based on transmission distance, safety requirements, and cost considerations. Buyers should prioritize actual application needs and avoid blindly pursuing higher voltage specifications.

LED Strip Voltage Rating Comparison

Voltage Rating‌‌	ข้อดีที่สำคัญ	Suitable Applications	Considerations
‌12V‌	High safety (no electric shock risk), soft light for eye protection, easy installation (self-adhesive backing)	Home decor (children’s rooms/stairs/cabinets), short-distance ambient lighting (study/balcony), auxiliary equipment lighting	Requires power extension beyond 5 meters to prevent voltage drop in long runs
‌24V‌	Minimal voltage drop (supports 10m without power boost), flexible cutting (cut every 6 lights), balances safety and efficiency	Home decor, commercial display cases/lightboxes, mid-range project lighting	Requires dedicated power supply, slightly higher cost than 12V systems
‌48V‌	Minimal line loss (current only half that of 24V), suitable for ultra-long series connections, high project stability	Large-scale architectural lighting, long-distance wall-washing, high-density illumination projects	Requires professional installation with stringent wiring requirements

Design Selection Recommendations

‌Safety-Priority Scenarios‌ (e.g., homes/children’s spaces): Opt for 12V systems for safety and installation ease. Pair with RGB strips for ambient lighting effects.

‌Commercial Short-to-Medium Range Applications:‌ Recommend 24V strips for balanced cost and performance. For display case lighting, ensure consistent brightness at cut points.

‌Large-Scale Projects:‌ Adopt 48V systems to minimize line losses. For example, when connecting over 50 meters of architectural outline lighting in series, the 48V voltage drop is only 1/4 that of 12V.

Buyer’s Guide

‌Residential Users‌: When selecting 12V strips, prioritize waterproof ratings (e.g., IP65 for balconies) and remote control functionality. Choose high-density LEDs (e.g., 60 LEDs/meter) to ensure uniform illumination.

‌Project Buyers‌: For 24V/48V strips, verify suppliers’ voltage drop test data and request 5m/10m brightness decay comparison reports.

Cost Control: 12V systems have lower initial costs but require power supplementation for long runs; 48V systems have higher unit costs but save on wiring and labor—evaluate total lifecycle costs comprehensively.

Important Notes: All voltages require high-quality power supplies to prevent voltage fluctuations that shorten lifespan. In humid environments (e.g., bathrooms/gardens), always select waterproof models (IP65 or higher). Test voltage drop before long-distance installations and use a segmented power supply when necessary.