Power injection, LED STRIP... Am I over thinking it?

[Lxkev]

I understand why we power inject and there lots of opions on what's best.

To me if x amount of pixels can draw 5amps, then they should have a 5amp fuse and appropriate cable supply, and disconnect from the next amount.

So I'm now using led tape ws2811. Sold in 5 meter length with 60 pixels a Meter. That's 18amps down the strip...

However, the cables attached to it or the copper tracks on the tape can't possibly support that.. so how on earth doesn't it go on fire?

 

[Skymaster]

The resistance of the strips limits the current. So the LEDs cannot draw their full current. Ultimately causing voltage drop, and loss of colour as you get below the minimum voltages for the B G and R segments.

 

[Lxkev]

The resistance of the strips limits the current. So the LEDs cannot draw their full current. Ultimately causing voltage drop, and loss of colour as you get below the minimum voltages for the B G and R segments.

So how does that effect power injection?

I'm currently looking at cutting the strip into 60 pixels lengths.. 600 pixels total.what would you do for power injection

 

[Skymaster]

What voltage strip are you using? and what brightness you intend to run at?

Assuming 100% -
For 5V, I would look at ensuring that you are no more than 50-75 away from a power injection point. So every 100-150 LEDs, or every 2m in your case.

At 12V it's a little more lenient. But not too much with strip due to way it's wired. Say 100 away from each PI point.

At 30%, you could safely double those numbers.

 

[Lxkev]

What voltage strip are you using? and what brightness you intend to run at?

Assuming 100% -
For 5V, I would look at ensuring that you are no more than 50-75 away from a power injection point. So every 100-150 LEDs, or every 2m in your case.

At 12V it's a little more lenient. But not too much with strip due to way it's wired. Say 100 away from each PI point.

At 30%, you could safely double those numbers.

Thanks for getting back to me. 100% and 5v..

Final question... When you power inject would you fuse to each segment or would you run a thick wire to all points.

 

[Skymaster]

It depends on the prop and how you're laying it out.

Both work and are acceptable, the advantage of fusing independently is that you have better protection and don't have you use larger more expensive wire. It's also inherently safer as you don't have large currents flowing.

But with independent fusing you need more cable obviously, and you may suffer cascading fuse failure of one line blows, as the others pick up the current and potentially get overloaded.

 

[thewanderingpine]

what are you doing between each 60 pixel length?

 

[TerryK]

Thanks for getting back to me. 100% and 5v..

Final question... When you power inject would you fuse to each segment or would you run a thick wire to all points.

I would suggest fusing each segment. Fuse protection isn't just for the strip or string but protection for the cabling from the supply to the power injection points too. As @Skymaster indicated, strip resistance plays a role in fuse 'opening' depending upon where a fault in either the strip (or string) occurs.