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I'm planning to illuminate a section of the house using some standard 5050 led strips.

However, All the parallel wiring examples I've seen have equal length strips. I was planning to have some strips of different lengths, like a 6m strip and a few 1m strips, connected in parallel to the same power source.

My limited (and very rusty) EE knowledge is telling me that this is probably a bad idea. I just wanted to double check here to see if what I'd like to do is actually viable (without additional circuitry or components).

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  • \$\begingroup\$ it won't matter because they are all in parallel anyway (at least each section is with respect to other cut-able sections) \$\endgroup\$ – dandavis Jun 13 '17 at 14:42
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    \$\begingroup\$ These strips usually consist of groups of (three LEDs and one current limiting resistor in series) in parallel. \$\endgroup\$ – Dampmaskin Jun 13 '17 at 14:42
  • \$\begingroup\$ Oh, I see, I had a feeling that might be the case. Thanks! \$\endgroup\$ – obuw Jun 13 '17 at 23:59
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LED strips with integrated resistors are designed to be cut in specific locations while retaining the same voltage requirement; all that changes is the current requirement, since there are now fewer parallel subcircuits.

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  • \$\begingroup\$ in other words: it's not a bad idea. \$\endgroup\$ – dandavis Jun 13 '17 at 14:51
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Yes, and no. The two issues here is that

  1. The strips are made up of multiple parallel segments of 3 series leds and a resistor. Typically. You can have any arbitrary number of strips of any arbitrary length (of full segments) without problems.

But

  1. The reality of electrical wiring hits. The longer the strip being powered, the higher the current, which causes a voltage droop due to the resistance of the wiring, or more importantly the copper in the the FPC. This leads to one side of the strip, closer to the power source, being brighter than the far side. This is where you need to take into consideration wiring size/gauge, and injecting power at multiple points or at both ends.

So yes, and no.

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  • \$\begingroup\$ Thanks for the answer. The longest segment I use will be less than 3m. I'll use a 12V 10A power supply that can handle a 10m strip (I think?), while my total length will be more like 8m. So hopefully I won't run into the "strip too long" issue? \$\endgroup\$ – obuw Jun 14 '17 at 0:05
  • \$\begingroup\$ @obuw At 3M or 9 feet, you may see some color difference at the end. For a normal 5M roll, its a bit obvious. You can solve this by simply powering that 3M strip in the middle. \$\endgroup\$ – Passerby Jun 14 '17 at 0:25

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