I’m interested in how people approach power supply selection for longer LED strip installations, particularly when the strip is used for several hours at a time.

Besides calculating the total wattage, what factors do you consider when choosing a suitable supply? For example, how much headroom do you normally allow, how do you account for voltage drop along the strip, and when would you recommend power injection at multiple points?

I’d be interested in hearing how others balance reliability, wiring complexity and efficiency in practical builds.

 

For simple series strings. just calculate voltage required to maintain the current at the rated Individual LED value.
Use a voltage regulayed supply

 

You don't just daisy-chain or ring-bus strip sections because the current flow will add up and end up too high for sections.
If a strip is say 5A and there are four, you'd end up with 15-20A being pulled through at the first strip- which is more than their design. And it can be more than the skinny wiring used.
So a star configuration is used, with each stub fused for only the stub's strip.

Safety is an issue for larger installations. You have to fuse wiring and stubs correctly. Although low voltage typically 12V, the high currents can cause a strip pcb foil or its wiring to glow start a fire. This was a problem in clubs. There is actually a safety standard for LED strip lighting resulting from this but it depends on your country.

 

You don't just daisy-chain or ring-bus strip sections because the current flow will add up and end up too high for sections.
If a strip is say 5A and there are four, you'd end up with 15-20A being pulled through at the first strip- which is more than their design. And it can be more than the skinny wiring used.
So a star configuration is used, with each stub fused for only the stub's strip.

Safety is an issue for larger installations. You have to fuse wiring and stubs correctly. Although low voltage typically 12V, the high currents can cause a strip pcb foil or its wiring to glow start a fire. This was a problem in clubs. There is actually a safety standard for LED strip lighting resulting from this but it depends on your country.

In a series arrangement you dont add all the currents together??????

 

In a series arrangement you dont add all the currents together??????

What total voltage are you thinking of?

I run LED strips in parallel to keep the voltage low (safe) and avoid the problem where a string that draws less current than the others gets overvoltaged cooks itself.

 

I’m interested in how people approach power supply selection for longer LED strip installations,

Be it a LED strip or anything else. I look at my voltage and current requirements and choose my power supply accordingly and normally apply a 20% over for current. So if I need 5 volts 800 mA I choose a 5 volt 1 amp supply.

Ron

 

OP it would help if you gave us an idea of the size/length of the LED strips you are talking about.
It this for a model train or a nightclub lol.

Another trick is to dial down the PSU voltage a bit, maybe 10% for everything to last longer.
Say from 12.0V to 11.3V because these parts from china are rated too much. When your LED strips unglue themselves due to their heat. The electrolytic capacitors are junky quality as well so the PSU's don't last. I will even derate 50% or swap in Nichicons, UCC parts etc. Better quality name brand like Meanwell PSU's in a cool location, with good airflow helps for long life.

 

In a series arrangement you dont add all the currents together??????

Long led strips are bunch of small circuit branches wired in parallel. When running several of such ropes, it is normal that they are connected in parallel, since all are operating at same voltage and disconnecting one does not kill others or change supply requirements.

For example 4x led string that run on 12V, can all run on 12V, which is simpler and more practical than choosing 48V supply.

But one could use 48V too, though damage to one led string could smoke the rest. Also running fewer led strings would require operation at different voltages (12V, 24V,36V).

And if the string is for higher voltage such as 24V , then connecting several of them in series is even less appealing.

So series connection is preferred for short strings (or segments), but for a long string that is just not practical.

Next, i totally agree with Prairiemystic that the parallel connection shall not be the simple daisy chain. Run separate wires to each long strip and fuse each separately.

 

Be it a LED strip or anything else. I look at my voltage and current requirements and choose my power supply accordingly and normally apply a 20% over for current. So if I need 5 volts 800 mA I choose a 5 volt 1 amp supply.

Ron

Thanks, Ron. Allowing around 20% headroom sounds like a useful starting point for supply selection. I suppose the actual requirements and operating conditions still matter, especially for longer runs where voltage drop and wiring losses can become significant.

 

OP it would help if you gave us an idea of the size/length of the LED strips you are talking about.
It this for a model train or a nightclub lol.

Another trick is to dial down the PSU voltage a bit, maybe 10% for everything to last longer.
Say from 12.0V to 11.3V because these parts from china are rated too much. When your LED strips unglue themselves due to their heat. The electrolytic capacitors are junky quality as well so the PSU's don't last. I will even derate 50% or swap in Nichicons, UCC parts etc. Better quality name brand like Meanwell PSU's in a cool location, with good airflow helps for long life.

Good point, I should have included a more specific example. I was thinking mainly of a 24V LED strip installation running for several hours at a time, rather than a particular project. The advice about PSU quality, airflow and heat is useful. Would you generally keep the supply voltage at the strip's rated value and manage brightness through a dimmer, rather than reducing the voltage at the PSU?

 

Would you generally keep the supply voltage at the strip's rated value and manage brightness through a dimmer, rather than reducing the voltage at the PSU?

I would run the LEDs at their rated voltage and if you want dimming LEDs are normally PWM (Pulse Width Modulation) for dimming. A Google of LED dimming should yield a few common circuit examples.

Ron

 

One more serious question: Have you verified that the polarity is correct?? Have you been able to get one single strip to light up??