LED Strip Power Supply Sizing - Complete South African Installation Guide

Proper power supply sizing is critical for LED strip installations. Undersized drivers cause poor performance and premature failure, while oversized units waste money. This comprehensive guide helps you calculate the perfect power supply for your South African LED strip projects.

Understanding LED Strip Power Requirements

Basic Specifications

Every LED strip has key specifications that determine power requirements:

Power consumption: Watts per meter (W/m)

• Low density: 4.8-7.2W/m
• Medium density: 9.6-14.4W/m
• High density: 19.2-28.8W/m
• Ultra-high density: 35W/m+

Voltage requirements:

• 12V DC: Most common for residential
• 24V DC: Better for long runs, commercial
• Constant current: Specialized high-power strips

Power Consumption Examples

5050 LED Strips (Popular in SA):

• 60 LEDs/m: ~14.4W/m
• 30 LEDs/m: ~7.2W/m
• Color options: Single color, RGB, RGBW

2835 LED Strips (High efficiency):

• 120 LEDs/m: ~9.6W/m
• 60 LEDs/m: ~4.8W/m
• Benefits: Higher efficacy, cooler operation

COB LED Strips (Premium):

• Continuous light: ~10-20W/m
• High CRI: 90+ for quality applications
• Applications: Accent lighting, task lighting

Power Supply Calculation Formula

Basic Calculation:

Required Power = Strip Power per Meter × Total Length × Safety Factor

Safety Factor Guidelines:

• 1.2 (20%): Standard installations, quality power supplies
• 1.3 (30%): Budget power supplies, challenging environments
• 1.5 (50%): Dimming applications, maximum safety margin

Step-by-Step Example:

Project: Under-cabinet kitchen lighting

• Strip type: 5050 LED, 60 LEDs/m, 14.4W/m
• Total length: 6 meters
• Safety factor: 1.2 (20%)

Calculation: 14.4W/m × 6m × 1.2 = 103.68W

Power supply selection: Choose 120W unit (next standard size up)

Standard Power Supply Sizes

Common 12V LED Driver Sizes:

• 30W: Up to 2m of 14.4W/m strips
• 60W: Up to 4m of 14.4W/m strips
• 100W: Up to 6m of 14.4W/m strips
• 150W: Up to 9m of 14.4W/m strips
• 200W: Up to 12m of 14.4W/m strips

Common 24V LED Driver Sizes:

• 60W: Up to 4m of 14.4W/m strips
• 120W: Up to 8m of 14.4W/m strips
• 200W: Up to 13m of 14.4W/m strips
• 320W: Up to 20m of 14.4W/m strips

Multiple Strip Calculations

Parallel Connection Example:

Project: Bedroom accent lighting

• Strip 1: 3m × 9.6W/m = 28.8W
• Strip 2: 4m × 9.6W/m = 38.4W
• Strip 3: 2m × 9.6W/m = 19.2W
• Total: 86.4W
• With 20% safety: 86.4W × 1.2 = 103.68W
• Power supply: 120W unit

Mixed Strip Types:

Project: Retail display lighting

• Main lighting: 8m × 14.4W/m = 115.2W
• Accent strips: 5m × 7.2W/m = 36W
• Total: 151.2W
• With 20% safety: 151.2W × 1.2 = 181.44W
• Power supply: 200W unit

Voltage Drop Considerations

Why Voltage Drop Matters:

• LED strips are sensitive to voltage variations
• Lower voltage = reduced brightness and color shifting
• Long cable runs increase voltage drop
• Undersized cables worsen the problem

Maximum Run Lengths (12V systems):

2.5mm² cable:

• 5A (60W): 8m maximum run
• 10A (120W): 4m maximum run

4mm² cable:

• 5A (60W): 12m maximum run
• 10A (120W): 6m maximum run

Voltage Drop Solutions:

1. Multiple Power Supplies

Instead of one 200W supply, use two 100W supplies for long runs

• Reduces cable runs
• Improves voltage stability
• Allows zone control

2. Higher Voltage (24V)

24V systems have half the current for same power

• Allows longer cable runs
• Reduces voltage drop issues
• Better for commercial installations

3. Thicker Cables

Use larger cable sizes for long runs

• 4mm² instead of 2.5mm²
• Reduces resistance and voltage drop
• Higher initial cost but better performance

Power Supply Types

Switching Power Supplies (Most Common)

Advantages:

• High efficiency (85-95%)
• Compact size
• Light weight
• Good regulation

Applications: Most LED strip installations

Linear Power Supplies

Advantages:

• Very low noise/ripple
• Simple circuit design
• Very reliable

Disadvantages:

• Lower efficiency (60-80%)
• Larger and heavier
• More expensive

Applications: Audio/video installations, medical equipment

Constant Current Drivers

Applications: High-power LED strips, commercial installations Benefits: Precise LED control, longer LED life Complexity: Requires matching driver to specific LED strips

Installation Environment Considerations

Indoor Applications (IP20)

Suitable for: Dry locations only Cost: Lowest cost option Examples: Under-cabinet lighting, display cases

Damp Location (IP44/IP54)

Suitable for: Bathrooms, covered outdoor areas Protection: Splash-proof enclosures Examples: Bathroom mirrors, covered patios

Wet Location (IP65/IP67)

Suitable for: Direct weather exposure Protection: Waterproof enclosures Examples: Outdoor architectural lighting, pool areas

Marine Environment (IP68)

Suitable for: Boat installations, underwater Protection: Submersion-proof Special requirements: Marine-grade materials

Quality and Reliability Factors

Power Supply Quality Indicators:

Efficiency Rating:

• Budget: 80-85% efficiency
• Standard: 85-90% efficiency
• Premium: 90-95+ efficiency

Certifications:

• SANS approval: Required for SA installations
• CE marking: European safety standards
• FCC: EMI/RFI compliance
• IP rating: Environmental protection

Warranty:

• Budget: 1-2 year warranty
• Standard: 3-5 year warranty
• Premium: 5-10 year warranty

Heat Management:

Quality power supplies include:

• Thermal protection: Auto-shutdown on overheating
• Fan cooling: For high-power units
• Heat sinking: Adequate thermal dissipation
• Derating curves: Reduced output at high temperatures

Dimming Considerations

Dimmable Power Supply Requirements:

Not all LED drivers can be dimmed. Look for:

• 0-10V dimming: Analog control signal
• PWM dimming: Digital pulse width modulation
• TRIAC dimming: Works with standard dimmers
• DALI dimming: Digital addressable lighting interface

Dimming Performance Factors:

• Minimum dim level: How low can it dim? (1-10% typical)
• Dimming smoothness: Steps or smooth transitions?
• Flicker-free: Important for video applications
• Color consistency: Maintains color at all dim levels?

Power Supply Sizing for Dimming:

Increase safety factor to 1.5 (50%) for dimmed applications

• Dimming circuits can be less efficient
• Power supplies may not regulate well at very low loads
• Extra headroom ensures stable operation

Cost Optimization Strategies

Single Large vs Multiple Small:

One 200W supply vs Four 50W supplies

Large supply advantages:

• Lower cost per watt
• Single installation point
• Easier troubleshooting

Multiple supplies advantages:

• Zone control capability
• Fault isolation
• Better voltage regulation over long runs

Quality vs Budget:

Budget power supply: R200-400

• Basic efficiency and regulation
• 1-2 year warranty
• Adequate for simple installations

Premium power supply: R600-1,200

• High efficiency and tight regulation
• 5+ year warranty
• Better for demanding applications

Long-term Cost Considerations:

• Higher efficiency saves electricity costs
• Better regulation extends LED strip life
• Longer warranty reduces replacement costs
• Quality units have better reliability

Troubleshooting Power Supply Issues

Symptoms and Causes:

LEDs Won't Turn On:

Possible causes:

• Power supply not receiving AC power
• Blown fuse in power supply
• Wrong voltage (12V strips on 24V supply)
• Wiring connection problems

Dim or Flickering LEDs:

Possible causes:

• Undersized power supply
• Excessive voltage drop in cables
• Poor connections
• Power supply approaching failure

Overheating Power Supply:

Possible causes:

• Overloaded beyond rated capacity
• Poor ventilation around power supply
• High ambient temperatures
• Internal component failure

Color Shifting in RGB Strips:

Possible causes:

• Voltage drop affecting different colors differently
• Insufficient power supply capacity
• Poor quality power supply regulation

Diagnostic Steps:

1. Measure voltage at power supply output (should be 12V/24V ±5%)
2. Measure voltage at LED strip (should be within 0.5V of supply)
3. Check current consumption vs power supply rating
4. Inspect all connections for corrosion or looseness
5. Verify power supply temperature is within normal range

South African Specific Considerations

Electrical Code Compliance:

• Power supplies must be SANS approved
• Installation by qualified electrician for fixed installations
• Proper earthing and circuit protection required
• RCD protection for wet locations

Local Availability:

Major suppliers:

• LED strip suppliers: Often bundle appropriate drivers
• Electrical wholesalers: Standard power supply ranges
• Online retailers: Wide selection but verify local support

Environmental Factors:

High altitude (Johannesburg region):

• Power supplies may need derating above 1,000m
• Check manufacturer specifications for altitude effects

Coastal areas:

• Higher IP ratings recommended due to salt air
• Stainless steel or marine-grade enclosures preferred

Future-Proofing Your Installation

Smart Controls Integration:

Plan for future smart home integration:

• Choose dimmable power supplies
• Consider addressable LED strips
• Plan for control wiring infrastructure

Expansion Planning:

Size electrical infrastructure for future expansion:

• Install larger conduits for additional cables
• Consider spare capacity in power supply sizing
• Plan junction boxes for future connections

Conclusion

Proper LED strip power supply sizing ensures reliable, efficient operation:

Key Takeaways:

• Calculate accurately: Strip power × length × safety factor
• Choose appropriate safety factor: 20% minimum, 50% for dimming
• Consider voltage drop: Use multiple supplies or 24V for long runs
• Match environment: IP rating appropriate for installation location
• Invest in quality: Better efficiency and reliability pay long-term dividends

Quick Selection Guide:

1. Calculate total power requirements including safety factor
2. Choose next standard size up from calculation result
3. Verify voltage drop is acceptable for your cable runs
4. Select appropriate IP rating for installation environment
5. Consider dimming requirements if applicable

Use our LED Strip Driver Sizing Calculator to quickly determine the right power supply for your specific LED strip installation.