Author Topic: Is 26 AWG wire sufficient for power to Pi pins?  (Read 1667 times)

AmadhiX

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Is 26 AWG wire sufficient for power to Pi pins?
« on: October 14, 2017, 02:43:27 AM »
It's in the title, but is 26 AWG wire enough to handle power to the Pi via the 5v/GND pins? 

The docs mention not to use poorly crimped wire, but don't specify an ideal gauge range.  I've read elsewhere that 22 AWG would be fine, but I happen to have a bunch of well-crimped 26 AWG jumpers handy, and would like to use them in a semi-permanent implementation, if they'll do.  I'd prefer a more educated opinion than my own on the matter before I potentially sabotage my project with under-gauged wires. :P

Thanks!

Felix

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Re: Is 26 AWG wire sufficient for power to Pi pins?
« Reply #1 on: October 14, 2017, 03:17:12 PM »
I would guess no, but try it, you will soon find out if the low voltage warning shows up.

TomWS

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Re: Is 26 AWG wire sufficient for power to Pi pins?
« Reply #2 on: October 14, 2017, 04:00:00 PM »
It's in the title, but is 26 AWG wire enough to handle power to the Pi via the 5v/GND pins? 

The docs mention not to use poorly crimped wire, but don't specify an ideal gauge range.  I've read elsewhere that 22 AWG would be fine, but I happen to have a bunch of well-crimped 26 AWG jumpers handy, and would like to use them in a semi-permanent implementation, if they'll do.  I'd prefer a more educated opinion than my own on the matter before I potentially sabotage my project with under-gauged wires. :P

Thanks!
Search for Ampacity of wire, you'll find a ton of tables (mostly related to residential house wiring), and there will be some that describe smaller gauge wire.  Since the Pi power supply it 2.5A, all you need to do is:
1. Make sure the gauge wire you're using has sufficient ampacity to support the power source,
2. that the voltage drop along the length of wire (x2 because you have drop in both directions) doesn't exceed the minimum supply limits of the Pi.
In other cases you might also have to worry about inductance, but in this case the Pi power supply will filter this issue away.

Tom


AmadhiX

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Re: Is 26 AWG wire sufficient for power to Pi pins?
« Reply #3 on: October 22, 2017, 02:25:08 AM »
Thanks, both of you!  For the record, I tested out the 26AWG jumpers and they seem to be able to hold it steady.  I may bump up the gauge before permanent installation, just to be safe, but I haven't seen the underpower symbol with them yet.

On the other hand, I was kind of a bonehead and tried to figure out the right fuse by looking at the one pictured on the Fuse Option page.  I ended up soldering an RXEF025 to one of my ATXRaspis.  I get the underpower symbol, and the fuse trips almost immediately.  I'm pretty sure its 0.5A trip load makes it way underpowered, based on this post: https://lowpowerlab.com/forum/atxraspi/recommend-poly-fuses-for-atxraspi/msg11911/

So, I basically destroyed one of my ATXRaspis. :\  I'll try to remove the join but I'm not the best at the hardware side of things, obviously.  :P  At least I ordered a backup!
« Last Edit: October 22, 2017, 02:08:29 PM by AmadhiX »

Felix

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Re: Is 26 AWG wire sufficient for power to Pi pins?
« Reply #4 on: October 23, 2017, 12:04:59 PM »
0.5A is not going to cut it. The Pi will draw nearly that at idle with no other accesories.
The fuse may be blown, but the board will not fry at that kind of load at all. It can support many amps of current. Overvoltage will fry it though so dont feed it more than 5.5V.