V+ from F8 distro

[steelth]

I originally wired my display like the first image, isolating V+ from the first power supply. However I kept blowing fuses for the downstream power injection lights on the F8 board. I didn't have time to troubleshoot so I removed 2 downstream  power injection wires and went with only the first power injection. While not ideal it worked without blowing any fuses .  Now I am trying to figure out why I originally kept blowing fuses.  Do you need to isolate V+ from power injection siteswhen using the f8 bistro board like in the 2nd image?
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[k6ccc]

Since you were able to power all the downstream pixels from the first PI point, there obviously was not enough current draw to blow fuses from the pixel load.  You might want to mention how many pixels are involved....
Now to answer your question, the standard advise is that you can have multiple injections points from the same power supply without isolating them (as shown in your first drawing).  You do have the potential to have a cascading fuse blowing situation when there is enough load that no one PI point can supply all the load for the string.  That results from one fuse blowing for whatever reason, which then adds to the load on the remaining fuses, causing them to blow.  Each blown fuse results in more current on the remaining fuses.  Obviously your 2nd drawing eliminates that as a concern.
There are also those that may tell you that even with different power supplies, you can supply different PI points that are not isolated (like your 1st drawing).  There are also those that will strongly tell you that you should never do it that way...
A good possibility is that something is wired wrong if you were blowing uses.  Your mission is to determine what was wired wrong.  Was it always the same fuse the blew?

[steelth]

Thanks for the reply.  Each strand was 105 pixels and I was using 12V power supplies.
It was always the 2nd power injection point fuse that would blow.  I used different wires, tried connecting the 2nd PI point downstream after the 3rd strand of pixels and even at the end of the 4th strand.  It would work for usually one evening but the next night the downstream 3 strands would not light up and the 2nd PI fuse would be blown.
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[jnealand]

My question would be - why do you need a 2nd power supply?  Looks to me like you could have hooked the F8 to the first power supply.  But without having knowledge of the physical environment it will be hard for anyone to give you another way to wire all these together.  I have several props with 240 pixels and I run from one port, but I power balance by running power from pixel one to the 240th pixel.  I also have a 541 node (using EVO pixels) that I do the same thing with.  A power cable is spliced between pixel 1 and pixel 541.  I run the above items at 30%.  I'm refering single prop wiring so if you are doing multiple prop wiring and have extension cords in the mix that changes everything.

[steelth]

I really don't need a 2nd power supply for this set up. However my Halloween show is my real labor of love! It is much much larger and complex than this simple set up.  I have been doing it for over 10 years but never using power injection. I was trying to learn the in's and out's of power injection with my basic Christmas setup in order to redesign and make my Halloween display more efficient without the miles of wire that it currently uses.