LED Strip Lighting: The Complete Guide
LED Strip Lighting: The Complete Guide
There is a moment when LED strip lighting gives itself away.
You walk into a room, the light looks good, and then you glance up at the cove or under the cabinet and you can see them. A row of individual bright points, like a line of tiny headlights. And the whole room quietly drops a price bracket.
Same technology, same idea, completely different result.
Strip lighting is now in almost every project, and it is also the product most likely to be specified badly, because the decisions that determine whether it looks like architecture or like a cheap upgrade are almost never printed on the front of the box. There are about six of them. This guide covers all six.
Why 24V Is Usually the Right Answer
Start with voltage, because it constrains everything downstream.
Strip is commonly available at 5V, 12V, 24V and 48V. For most architectural work, 24V is the sensible default, and the reason is worth understanding rather than taking on trust.
Power equals voltage multiplied by current. So for a strip drawing a given number of watts per metre, doubling the voltage halves the current.
At 14.4 watts per metre, a common architectural density:
| Voltage | Current per metre |
|---|---|
| 12V | 1.20 A |
| 24V | 0.60 A |
| 48V | 0.30 A |
And voltage drop is current multiplied by resistance. Halve the current and you halve the drop along the run.
Here is what that means in practice. Take a 5 metre run at 14.4 W/m, on cable with a round-trip resistance of roughly 0.007 ohms per metre:
- At 12V: 6.0 amps total, producing a drop of about 0.42V, which is 3.5 percent of the supply.
- At 24V: 3.0 amps total, producing a drop of about 0.21V, which is 0.9 percent.
Same strip output, same cable, four times less proportional loss. That is the whole argument for 24V, and it is arithmetic rather than marketing.
When to use something else. 12V remains fine for short runs, under-cabinet lighting, and where you are working with an existing 12V system. 48V is worth considering on very long architectural runs. 5V is mostly for addressable pixel work and is the most sensitive to voltage drop of all.
How Long a Run Can Actually Be
This is the question that causes most site problems, and the honest answer is that it depends on the specific strip.
Working figures in common use:
| Voltage | Fed from one end | Fed from both ends |
|---|---|---|
| 12V | around 5m | around 10m |
| 24V | around 10m | around 15 to 20m |
| 48V | around 15 to 20m | longer still |
Treat these as planning figures, not guarantees. The real limit depends on the strip's wattage per metre, the copper weight on the tape itself, and your cable sizing. A 24V strip at 24 W/m will not run as far as a 24V strip at 9.6 W/m.
Three ways to fix a run that is too long, in rough order of how well they work:
Feed from both ends. The simplest fix, and it roughly doubles the workable length because each half of the run only carries half the current.
Split into separate home runs. Rather than one continuous line, run several shorter segments each fed independently from a distribution point near the power supply. This is what professional installations do, and it also makes fault-finding far easier later.
Power injection at intervals. Feeding additional power into the middle of a long run. Effective, but it means cable arriving at points along the run, which needs planning at first fix.
One thing that is not a fix: turning the brightness up. The far end will still be proportionally dimmer than the near end.
Copper weight matters and nobody mentions it. Architectural-grade tape uses heavier copper on the flexible circuit board itself, commonly described as 2oz rather than 1oz. That reduces resistance within the strip, which reduces drop along its length. If two strips look identical on paper and one costs noticeably more, this is often why.
Sizing the Power Supply
Straightforward arithmetic, and getting it wrong is one of the most common causes of premature failure.
Total load = length in metres multiplied by watts per metre.
Then add headroom. Running a power supply continuously at its rated maximum shortens its life, and industry practice is to size at 20 to 50 percent above the calculated load. Around 20 percent is generally acceptable in a cool, ventilated location. Closer to 50 percent is better in an enclosed or warm one.
| Run | Load | Power supply |
|---|---|---|
| 5m at 14.4 W/m | 72W | 86W to 108W |
| 10m at 14.4 W/m | 144W | 173W to 216W |
| 3m at 24 W/m | 72W | 86W to 108W |
Where you put the driver matters as much as its rating. It needs to be accessible for replacement, ventilated so it is not cooking itself in a sealed void, and somewhere any faint electrical noise will not be noticed. A driver buried permanently in a plasterboard ceiling is a future problem you have designed in.
The Aluminium Profile Is Not Optional
Strip is often installed bare, taped straight to a surface. It is the single biggest quality difference between a good installation and a poor one, and it does three separate jobs.
It takes heat away from the diodes. LEDs degrade faster when they run hot, losing output and shifting colour over time. An aluminium extrusion acts as a heat sink. This is the difference between a cove that looks the same in year five and one that does not.
It keeps the line straight. Adhesive-backed tape stuck along a wall follows every imperfection in the surface, and a wandering line of light is visible even when the strip itself is hidden.
It carries the diffuser. Which brings us to the thing everyone actually notices.
Dots, and How to Not Have Them
The visible-dot problem has two solutions and they are not interchangeable.
A diffuser cover, usually frosted or opal acrylic in the profile, blends the individual points into a continuous line. How well it works depends on the distance between the diodes and the diffuser, so a deeper profile diffuses better than a shallow one.
COB strip, which stands for chip on board, is the other answer. Rather than discrete diodes spaced along a board, COB uses a continuous phosphor-coated emitting surface. There are no points to see at any viewing distance.
How to choose:
Use COB where the strip is shallow, viewed close up, or where the light line itself will be visible rather than concealed.
Conventional strip with a good diffuser in a deep profile is perfectly acceptable where the source is well concealed and viewed from a distance, and it is usually cheaper.
Never install bare strip anywhere it can be seen, including in reflections. A polished worktop or a glass shelf will show you the diodes even when the strip itself is hidden.
The Colour Problem That Appears After Installation
Two specifications matter here, and the second one catches people out.
Colour rendering
Specify CRI 90 minimum, and CRI 95 with R9 above 50 where finishes matter. Strip lighting typically washes large areas of ceiling, wall or worktop, so poor colour rendering is spread across a lot of surface. Timber goes flat, stone goes grey, and food and skin look slightly wrong without anyone identifying why.
R9 measures deep red rendering specifically and is excluded from the headline CRI figure, so a strip can score CRI 90 and still render warm materials poorly.
Colour consistency between reels
Here is the one that appears on site rather than on paper.
Strip is manufactured in reels, and LEDs are sorted into bins by their actual colour output, because no manufacturing process produces identical diodes. Two reels of the same nominal 3000K product, from different production batches, can be visibly different colours when installed end to end.
The measure is SDCM, standard deviation of colour matching, expressed in MacAdam steps. Specify SDCM of 3 or less for architectural work. And on any run spanning multiple reels, ask for reels from the same batch at the point of ordering, not after delivery.
IP Ratings
| Location | Minimum |
|---|---|
| Dry interior, coves, shelving, joinery | IP20 |
| Kitchen splashback zones, bathroom outside the wet zones | IP44 |
| Bathroom wet zones, external sheltered | IP65 |
| Ground level exterior, anywhere water pools | IP67 |
| Submerged | IP68 |
Two practical notes. Silicone-jacketed strip at high IP ratings diffuses slightly differently from bare strip in a profile, so mixing the two in a single sightline can produce a visible difference. And higher IP ratings trap heat, which makes the profile and thermal management more important rather than less.
One regulatory point that catches people out. In a bathroom, the IP rating alone is not the whole requirement. Bathrooms are treated as special locations in the wiring regulations of most countries, with defined zones around the bath and shower that set minimum ratings and, in the closest zones, restrict you to extra low voltage supplied from a transformer located outside those zones. A strip behind a mirror or inside a shower niche needs checking against the zone it actually occupies, not just against a general IP figure. Confirm the requirement with your electrician against the regulations in force locally.
Dimming, and Why Some Strip Flickers on Camera
Strip lighting dims well, and the specification detail that matters is how it dims.
PWM, or pulse width modulation, dims by switching the LEDs on and off very rapidly and varying the proportion of on-time. It is efficient and holds colour consistently across the dimming range. The catch is that it introduces flicker, and if the switching frequency is low, that flicker becomes visible on camera even when the eye cannot see it.
Constant current reduction dims by lowering the current instead. It avoids the flicker problem but can shift colour slightly at low output.
What to specify:
- For most architectural work, PWM at a high switching frequency is fine. Ask for the frequency and prefer several kilohertz or above.
- Anywhere that will be filmed, including kitchens and home offices used for video calls, prioritise flicker performance explicitly and ask for the flicker metrics rather than assuming.
- Confirm the control protocol at the start: 0 to 10V or DALI for architectural installations, since the choice determines the driver for every run in the scheme.
- Confirm driver and dimmer compatibility together before ordering. Most dimming failures are a mismatch between components that each work fine on their own.
Where Strip Lighting Actually Earns Its Place
Strip does three things well: lights a surface it sits close to, defines an edge, or makes something appear to float. It does not light a room.
Ceiling. Perimeter cove washing the ceiling plane. A shadow gap at the wall junction for a finer line. Around a dropped bulkhead so it hovers rather than sits.
Joinery. Under shelf front edges, which puts light in front of the contents rather than behind you. Inside glazed cabinets. Under plinths, for the float effect and as night light. Behind a headboard or panelled wall.
Kitchen. Under wall cabinets, mounted toward the front edge so light lands on the worktop rather than the splashback. Inside recessed niches. Under an island overhang.
Bathroom. Behind a mirror as a halo, though for seeing your face properly the light needs to come from beside the mirror at face height. Inside a shower niche. Under a floating vanity.
Stairs and outside. Under a nosing aimed downward, defining each tread edge. Along a handrail, below eye level. In external soffits, grazing a facade.
And three places it fails. As the only light in a room, because it has no focus and nowhere for the eye to settle. Anywhere it will be reflected, since a polished worktop shows the diodes even when the strip is hidden. And anywhere the strip or driver cannot be reached, which gives the detail a lifespan measured by its first failure.
LED Strip Specification Checklist
Electrical
- 24V as the default, 12V only for short runs, 48V for very long ones
- Run length checked against the specific strip's wattage per metre
- Feed strategy decided: both ends, separate home runs, or injection
- Power supply sized at load plus 20 to 50 percent headroom
- Driver location accessible, ventilated, and acoustically sensible
- Copper weight confirmed on long architectural runs
Optical
- Aluminium profile specified for every run, not just visible ones
- COB where shallow, close-viewed, or the line itself is seen
- Diffuser depth adequate for the diode spacing
- No bare strip anywhere visible in direct view or in reflections
Colour
- CRI 90 minimum, 95 with R9 above 50 where finishes matter
- SDCM 3 or less specified
- Same production batch requested for multi-reel runs
Control and environment
- IP rating matched to the actual location
- Dimming protocol chosen at design stage
- Driver and dimmer compatibility confirmed together
- Flicker performance specified where anything will be filmed
Six Mistakes With LED Strip
1. Bare strip with no profile. Loses heat management, loses straightness, loses the diffuser. It is the single clearest difference between a considered installation and a cheap one.
2. Choosing 12V by default. For the same output, it draws twice the current and suffers four times the proportional voltage drop over the same run.
3. Running a power supply at its limit. Add 20 to 50 percent headroom, and put it somewhere it can breathe and somewhere you can reach it.
4. Mixing reels without checking batch. Two nominally identical 3000K reels can be visibly different colours end to end. Specify SDCM 3 and request matched batches.
5. Ignoring reflections. A polished worktop or glass shelf will show the diodes even when the strip itself is perfectly concealed.
6. Treating dimming as an afterthought. The protocol determines the driver on every run in the project, so it needs deciding at the start rather than discovered at commissioning.
Frequently Asked Questions
Should I use 12V or 24V LED strip? 24V for most architectural work. Power equals voltage multiplied by current, so for the same wattage per metre a 24V strip draws half the current of a 12V one. Since voltage drop is current multiplied by resistance, halving the current halves the drop. On a 5 metre run at 14.4 W/m, a 12V strip loses roughly 3.5 percent of its supply voltage along the run while a 24V strip loses about 0.9 percent, four times less proportionally. 12V remains fine for short runs and under-cabinet work, and 48V is worth considering on very long architectural runs.
How long can an LED strip run be? Working figures are roughly 5m for 12V and 10m for 24V when fed from one end, extending to around 10m and 15 to 20m respectively when fed from both ends. Treat those as planning numbers rather than guarantees, because the actual limit depends on the strip's wattage per metre, the copper weight on the tape itself and your cable sizing. A 24V strip at 24 W/m will not reach as far as one at 9.6 W/m. The fixes, in order of usefulness, are feeding from both ends, splitting the installation into separate shorter home runs, and power injection at intervals.
What is COB LED strip and when should I use it? COB stands for chip on board. Instead of discrete diodes spaced along a circuit board, it uses a continuous phosphor-coated emitting surface, so there are no visible points of light at any viewing distance. Use COB where the strip sits in a shallow recess, will be viewed close up, or where the line of light itself is meant to be seen. Conventional strip behind a good diffuser in a deep profile is perfectly acceptable, and usually cheaper, where the source is well concealed and viewed from a distance.
Why do two LED strips of the same colour temperature look different? Because LEDs are sorted into bins by their actual measured colour output, and two reels of the same nominal 3000K product from different production batches can sit in different bins. The measure is SDCM, standard deviation of colour matching, expressed in MacAdam steps. Specify SDCM 3 or less for architectural work, and on any run spanning several reels, request reels from the same production batch at the point of ordering. Discovering a mismatch after installation usually means replacing the whole run.
What CRI should LED strip have? CRI 90 minimum, and CRI 95 with R9 above 50 where materials and finishes matter. Strip lighting typically washes large areas of ceiling, wall or worktop, so poor colour rendering is spread across a lot of visible surface. R9 measures deep red rendering specifically and is excluded from the headline CRI average, so a strip can score CRI 90 while still making timber look flat and warm stone look grey.
Why does my LED strip flicker on camera? Most likely because it dims using pulse width modulation at a low switching frequency. PWM works by switching the LEDs on and off very rapidly and varying the proportion of on-time, which is efficient and holds colour well, but it introduces flicker that a camera sensor can pick up even when the eye cannot. Ask the supplier for the PWM switching frequency and prefer several kilohertz or above. The alternative, constant current reduction, avoids flicker but can shift colour slightly at low output. Anywhere that will be filmed regularly, specify flicker performance explicitly rather than assuming.
Notice
This article is published by Archlior for general information and educational purposes. It is written for architects, interior designers and specifiers as an introduction to specifying LED strip lighting.
It is not professional lighting design advice, electrical engineering advice, or a statement of regulatory compliance for any project.
Run lengths, power supply headroom, IP requirements and colour specifications given here reflect industry design practice and manufacturer guidance rather than mandatory standards. Actual performance depends on the specific product, its wattage per metre, its conductor construction, cable sizing, ambient temperature and installation conditions, and must be verified against the manufacturer's own data for the products being used. The voltage drop calculations shown are worked illustrations using stated assumptions, not predictions for any particular installation.
All electrical work must be carried out by a suitably qualified electrician working to the regulations in force locally, and low voltage lighting installations remain subject to wiring regulations covering cable sizing, protection and installation methods.
Archlior accepts no liability for any loss, cost or damage arising from reliance on the information in this article. Readers act on it at their own discretion and remain responsible for compliance with all applicable regulations.
Last reviewed: August 2026.