Noob Questions

JohnsRdChristmas

Full time elf
Joined
Dec 12, 2016
Messages
131
Location
Central Coast
Looking to run passed my gutter line setup, as really not sure if im on the right track,
And as iv just bought a house, i would rather not burn it down :p

I am running some ws2811 60 led per meter strip, which come in 5mtr lengths,
I have purchased a ton of Ray Wu's pigtails and extension leads

I was going to run 4 lengths of strip, 5mtr, 3mtr, 5mtr, 3 mtrs (so 16mtrs)
And power it off a power supply i have got from 3d printers, (240watt, 20 amps ) and i know that these are cheap Chinese PSUs so shouldn't really be run at any more then 75% so 180watt max, ( I have a few of these so can run multiple if need be)


Questions:

1. - Watts
The strip according to the packaging states maximum power is 36w,
( The packet is for 5mtr roll, so presuming that it is for the roll)
but different calculators i have looked around have it at around 50 watts,

Do i believe the packet?? if so that is 7.2watts per MTR
7.2watts x 16mtrs = 115.2watts
(If thats the case, then im good)


2. - Amps (& Fuses)
I have not thought about it until now, but should fuse each of the power lines for safety, in-case water gets in
and creates a short,
In which case i have ordered some 8 way fuse boards from da-share.com,

I cannot find amp specs on for the strip, but have tested myself???
I have put a multi meter (in amp mode) in the power line before a strip (running power through multi meter)
On full white it draws between 3 - 3.5 amps, (no power connected at end and the colour does dip a little on white at the end - normally would have power injection at end but for the purpose of the test i didnt)
On colours (sample show sequence) it runs around 1.5 - 2.5 amps,

My conclusion
Watts - Now giving a bit of room for overhead, im guessing i can in theory run all 4 strips together off the 1 power supply and the power supply should be fine

Amps (Fuses and Wiring) If i fuse each power line with a 7.5amp fuse then i should be safe, however not sure how best to connect the strands


Can i connect all 4 together like the picture, or do i need to separate it a little, are the fuses effective if there are 5 leeds connected together essentially?
Maybe i should be connected only 2 strips together and have power at start, between and end,


Thoughts?
I really appreciate all the help and advice, I think i am on the right track but safety is important so best to check,

Many thanks

Ben
 

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Nuzzy

Apprentice elf
Joined
Aug 6, 2017
Messages
75
Location
Denmark
I usually work to around 7 watts per metre for a 30 led/metre strip so I would assume a 60 led/metre would be close to double that, maybe around 12 watts/metre.
 

JohnsRdChristmas

Full time elf
Joined
Dec 12, 2016
Messages
131
Location
Central Coast
Hey Dez / Nuzzy

One thing I forgot to mention previously was that all the testing was at 100% brightness (which ofcorse I design for) but when I actually had it up for Christmas 30% was fine, as such all my specs were well under and everything (for roofline) ran flawlessly,

And I had a second psu with a group of elements in front yard and the fuses did their job,
I had water get into an element and blew a fuse, so glad I put them in,

Was a great first year and learnt a lot and already looking to start designing and costing out next year's setup, got the green light from the wife!!

Many thanks for the replies, hope you both had a great tg season,
 
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