22AWG Pig Tails- Are they to small ?

[Mikeynz]

So in my rush to order everything for this Xmas , I seem to have ordered 22 AWG 3pin connectors , not 18AWG everyone is using …. I haven’t soldered them to my lights yet , so I’m asking should I re-order 18 AWG ones or could I get away for this year the 22 AWG

I’m running 5V pixels , 50 pixels per controller port max on my mega tree. All running off a 32port Controller. So not pushing each strip to hard, If I set the brightness to 30% , keep my run from the controller to lights to 2m - do you think I will be safe - or no go ?

Dont want to blow up our new house.

Thanks
Mike

 

[i13]

There are two considerations when choosing the wire gauge. One is the maximum current that it can handle and the other is the voltage drop.

Calculating the maximum current:
Each WS2811 pixel draws no more than 0.0555 amps at 100% brightness white. Some draw less. Multiplying this by 50 pixels gives a current of 2.775 amps. Your pigtails will be stranded (multi-core) wire. Going by this table, you're likely to exceed the maximum current that the wire can handle. Lowering the pixels to 30% brightness would reduce the current to 30% which is a much more reasonable 0.8325 amps. I would suggest fusing just below the maximum current that the wire can handle. The reason for this is that when you lower the pixel brightness, you're relying on the data signal to limit current flow and prevent the wires from overheating. If this data signal goes corrupt or you misconfigure something, you could overheat the wires.

Calculating the voltage drop:
22 AWG copper wire has a resistance of 0.0052 ohms per metre. If your wires are two metres long, that's a four metre circuit because the current completes a loop. You therefore have 0.0208 ohms of resistance. Ohm's law states that the voltage drop is equal to the current flow in amps multiplied by the resistance in ohms. We already know that at 30% brightness, the current won't exceed 0.8325 amps. Multiplying this by 0.0208 ohms means you lose 0.01736 volts between the controller and first pixel. This is insignificant and not a problem.

In summary, I think these wires will do the job but I would recommend fusing to prevent them from overheating in the scenario where you exceed the set brightness either by accident or due to a corrupt data signal.

I'll also point out that suppliers in China may claim that the wire is 22 AWG but in reality, it could be less. You could test this by measuring the resistance, determining the actual AWG and repeating my calculations if needed. Another worthwhile test might be to measure the actual current draw of the pixels. Some draw less than 0.0555 amps.

 

[Mikeynz]

Thank you for this, been a great help. Thanks

 

[Eebado]

Thanks for the response, I actually had this same question as I ordered some cheap 3 pin connectors from AliExpress without realizing how tiny they were! Getting smaller fuses makes a lot of sense to protect the wire.