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Can I use a Slim LED Power Supply with different LED strips?

by karla•

If you’ve ever browsed for LED power supplies, chances are you’ve come across the term “slim LED power supply” — a compact, low-profile unit designed to squeeze into tight spaces like under-cabinet LED runs, recessed sign housing, or slim-profile linear lighting fixtures. As someone who’s spent the last 8 years running a company that manufactures and distributes these slim power supplies, one of the most common questions I hear from electricians, DIYers, and lighting designers alike is: “Can I use a slim LED power supply with different LED strips?” Slim LED Power Supply

It’s a fair, practical question. LED strip projects often evolve — you might start with a 16-foot warm-white strip for your kitchen, then add a 8-foot cool-white accent strip for your dining nook a few months later, or swap in a RGB strip for a party. The last thing anyone wants is to buy a new power supply every time they change up their strip setup, especially when slim power supplies are priced higher than bulkier traditional units. But the answer isn’t a simple “yes” or “no” — it’s rooted in how both slim LED power supplies and LED strips work, and how to match them safely and effectively. Let’s break it down, with real-world lessons from the projects my team has supported over the years.

First, let’s cut through the jargon to get the basics right. LED strips are low-voltage devices — almost always 12V DC or 24V DC, rarely 5V for tiny portable strips. Unlike old incandescent strips that ran directly on line voltage (120V/240V), LEDs are finicky: too much voltage and they burn out fast; too little and they dim, flicker, or don’t light at all. That’s where the power supply comes in: it converts high-voltage AC household current to the low, consistent DC voltage LED strips need.

Slim power supplies, as the name suggests, are built to be thin — usually under 1.5 inches thick, which is why they’re so popular for under-cabinet work where a bulkier 2-inch power supply would stick out or require modifying cabinetry. But that slim form factor comes with tradeoffs: most high-quality slim supplies are constant-voltage (CV) units, meaning they output a fixed 12V or 24V DC regardless of how much current your strip draws. They also have a specific maximum current (measured in amps) they can output, which translates to a maximum wattage (watts = volts x amps). For example, a 24V slim power supply rated at 5 amps is 120 watts total (24V x 5A = 120W), while a 12V 10A slim supply is 120 watts too.

Now, the first rule of pairing a slim power supply with any LED strip: the strip’s rated voltage must match the power supply’s output voltage. This is non-negotiable. I’ve seen too many mistakes here, including a home renovation client who tried to use a 12V slim power supply for a 24V RGB strip — the strip lit up for 10 minutes before half its pixels burned out. Because LED strips are wired in parallel (each set of LEDs gets the same voltage across its two ends), mismatched voltage means each LED gets either too little or too much power. A 12V strip needs exactly 12V; a 24V strip needs exactly 24V. Your slim power supply will always be labeled clearly with its output voltage on the casing, so double-check that before even thinking about current. That’s the first box to tick.

The second, most critical factor is total power draw of all the strips you’re running, which needs to be at or below the slim power supply’s maximum rated wattage. This is where “different LED strips” gets tricky, because not all strips draw the same amount of power. LED strip wattage is usually listed per foot: a standard warm-white 2835 strip draws 4.8 watts per foot at 12V, while a high-brightness 5050 RGB strip might draw 12 watts per foot at 24V. Let’s do a quick example to make this concrete. Suppose you have a 10-foot 12V warm-white strip (4.8W/ft x 10ft = 48W) and an 8-foot 12V cool-white strip (same 4.8W/ft = 38.4W). Total draw is 86.4W. Now, if you have a 12V slim power supply rated at 10A (which is 120W total), that’s more than enough — you can run both strips off the same unit. But if you tried to add a 10-foot RGB strip that draws 10W/ft (100W) to the mix, total draw would jump to 186.4W, which would exceed the slim supply’s 120W max. That’s a problem: not only would the power supply overheat (slim units have smaller heat sinks, so they run hotter when overloaded), but the strip would flicker as the supply can’t deliver enough consistent current, and it could damage both the supply and the strips over time.

Wait, but what if you want to mix strips of different voltages? Like, a 12V under-cabinet strip and a 24V RGB accent strip? That’s a hard no. A single slim power supply can only output one fixed voltage. So if your strips run on different voltages, you’ll need two separate slim power supplies — one for 12V, one for 24V. The good news is that many of my customers opt for our dual slim power supply kits when they have mixed voltage projects, since they’re both low-profile and easy to hide in separate tight spaces.

Now, let’s talk about common edge cases that trip people up, and how a slim power supply’s design interacts with different strips. First: dimmable strips. If you’re using dimmable LED strips (whether warm-white, cool-white, or RGB), you need a slim power supply that’s compatible with your dimmer type. Most slim power supplies are compatible with leading-edge (TRIAC) dimmers, which are the most common for residential use, but some older or budget slim units aren’t rated for trailing-edge dimmers or DMX controls for professional RGB projects. When we’re consulting with customers, we always ask if they need dimming functionality upfront — that’s a detail that makes or lessens compatibility. For example, if a customer wants to use a DMX dimmer for a stage lighting project with multiple RGB strips, we’ll point them to our DMX-compatible slim power supply, which has built-in signal filtering to handle the high-frequency signals without flickering. Budget slim units often skip that filtering, so they can’t handle advanced dimming.

Another edge case: long LED strip runs. LED strips have a maximum recommended run length because voltage drops over distance. For a 12V strip, the recommended maximum is about 16 feet; for 24V it’s up to 32 feet, because higher voltage means less resistance over wire. If you have a 20-foot 12V strip, you might be tempted to run it off a single slim power supply — but wait, the voltage drop would make the first 10 feet super bright and the last 10 feet dim. That doesn’t mean the slim power supply is incompatible, but it means you’ll need to either split the strip into two runs connected in parallel to the power supply, or install the power supply halfway along the strip. This is a key point when you’re mixing strip lengths: a slim power supply’s current rating also factors into how far you can run the strip, because longer runs need more current to combat voltage drop. My team once helped a customer with a 50-foot linear sign project that used 24V strips — they used two 24V 10A slim power supplies, installed at each end of the strip, to eliminate voltage drop entirely. It worked perfectly, and both units fit in the sign’s 1-inch thick housing, which was the original requirement.

Now, let’s address a question I get all the time: “Can I use a higher-amp slim power supply than I need for my strip, so I can add strips later?” Technically, yes — as long as you don’t exceed the power supply’s max voltage. For example, if your initial project uses a 12V 5A strip (60W), buying a 12V 10A slim power supply (120W total) gives you headroom for adding another strip down the line, or for the strip to draw a little extra current if it’s a higher-brightness model than you originally planned. But here’s the catch: don’t buy a power supply that’s way too big. A 100W power supply is more efficient at 50% load than a 1000W supply running at 10% load — inefficient units waste energy and run hotter, which shortens their lifespan. Slim power supplies already have smaller internal components, so overbuying in a big way can lead to premature failure. Our recommendation is to calculate your total current needs, then pick a slim power supply that’s 10-20% over that number for headroom — enough to add a small strip later, but not so much that you waste energy.

What about non-LED strips? Wait, some people call neon flex strips “LED strips” too, and there’s a common question about using slim power supplies with those. Neon flex is usually 12V or 24V, just like LED strips, but it has a slightly different power draw per foot. For example, a 12V neon flex might draw 6W/ft vs. 4.8W/ft for a standard LED strip. The same rules apply: match the voltage, calculate total wattage, stay under the power supply’s max. But again, slim power supplies work here — we’ve had thousands of neon flex projects use our slim units successfully. The only exception is if you have a high-power neon flex that draws more than the slim supply’s max wattage, which is rare for neon runs under 20 feet.

Now, let’s cover the mistakes that cause the most issues, and how to avoid them. First mistake: ignoring voltage. I can’t stress this enough — mismatched voltage is the #1 reason for early LED strip or power supply failure. Second mistake: miscalculating total wattage. People often only calculate the power of one strip, not adding in all the strips they plan to run. Third mistake: using a slim power supply for high-temperature environments. Slim power supplies have compact heat sinks, so they don’t handle continuous high heat (like in a sealed attic or near a furnace) as well as bulkier units. If your project is in a hot area, you’ll want a slim power supply rated for high ambient temperatures, which most of our units are, but it’s worth checking the specs. Fourth mistake: not using the right gauge wire. If you’re running a long strip, thin wire can cause voltage drop even if your power supply is rated correctly. For 12V strips over 16 feet, use 18-gauge wire; for 24V strips over 32 feet, use 20-gauge. This isn’t a power supply issue, but it directly impacts how well it works with your strips.

So, to circle back to the original question: yes, you can use a slim LED power supply with different LED strips — but only if you follow three core rules:

  1. Every strip runs on the same voltage as the power supply (all 12V strips, or all 24V strips, no mixing voltages on one supply).
  2. The total wattage of all strips is at or below the power supply’s maximum rated wattage, with 10-20% headroom for future additions.
  3. You account for strip length and voltage drop, using the right gauge wire and possibly splitting long runs or using additional power supplies for very large projects.

The key here is that “different LED strips” just means different types, lengths, or brightness levels — as long as their electrical specs align, a quality slim power supply will work seamlessly. The last thing we want is for someone to pass on a slim power supply because they’re worried about compatibility, when all it takes is a quick spec check.

If you’re planning an LED strip project and want to make sure your slim power supply choice works for your setup, we’re here to help. Whether you’re a contractor working on a commercial installation, a DIYer tackling a home reno, or a designer putting together a custom lighting project, our team can walk you through calculating your power needs, confirming compatibility with any strips you have, and matching you with the right slim power supply for your space. Reach out to discuss your project details today.

High Voltage Cabinet Lights References

  1. Lighting Design Lab. (2021). Low-Voltage LED Lighting System Compatibility Guidelines. Pacific Northwest National Laboratory.
  2. National Electrical Code (NEC). (2023). Article 410: Lighting Fixtures, Luminaires, and Lamp Holders. National Fire Protection Association.
  3. LED Strip Technical Manual. (2022). General Specifications for Low-Voltage LED Strip Products. LED Industry Association.
  4. Power Supply Design Guide for LED Lighting. (2020). Compact Constant-Voltage Power Supply Performance Standards. International Electrotechnical Commission.

Foshan Gedi Electrnoic Co., Ltd.
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