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I'm building an Arduino-controlled Christmas light show. I power my 16-channel relay module with a 5V, 30A supply. It is placed outside the house and I want to place its power supply powering the relays inside.

I will have to run a wire from my workstation (where I set up my controlling PC and Arduino) outside to the spot where I placed my relay module (it needs a 10-12m long wire.)

I'm afraid that if I use an incorrect type of wire unsuitable to handle 5V, 30A, it would burn the wire.

Is there any thin wire that I could run for 10-12m carrying 5V, 30A power? Is there any type of wire that is thinner but still handles the power?

(Edited: I only need it to power the relay module, not the Christmas lights.)

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    \$\begingroup\$ Why 30 amps? What are you powering that needs 30A and that needs relays? \$\endgroup\$
    – bobflux
    Commented Nov 22, 2021 at 16:34
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    \$\begingroup\$ 30 amps requires reasonably thick wire, there's no way around that. Using a higher voltage and lower current would allow thinner wire. \$\endgroup\$
    – Hearth
    Commented Nov 22, 2021 at 16:40
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    \$\begingroup\$ Why 5V? With 30A, the loss is "great", considering 5V. Place a transformer near the Christmas lights, and send 48V... I = (5 x 30 x 1.5) / 48 ==> 5A. \$\endgroup\$
    – jay
    Commented Nov 22, 2021 at 16:41
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    \$\begingroup\$ Do you actually need 30 amps at your load, or are you just looking at the 30 amp rating of the power supply and assuming that's the number you need to use? \$\endgroup\$
    – Hearth
    Commented Nov 22, 2021 at 16:43
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    \$\begingroup\$ @jay Sounds like this is DC, so a little more complex than a transformer. I would just put multiple lights in series and run them off 48 volts directly. \$\endgroup\$
    – Hearth
    Commented Nov 22, 2021 at 16:44

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If you're using the usual cheap "arduino relay module" it uses 70mA per relay, so 1.1A for 16 relays. So that's the current you'll actually need.

Basically any zipcord/lampcord/whatever wires around 1mm2 or more will do. I'd recommend using the usual "5V 2A" cellphone charger as a power supply. If you really want to use the 30A power supply, then you need to add a fuse on the 5V output so it doesn't melt the wires in case of a short.

That's assuming you're using the 30A power supply because you got it lying around but you're just powering the relay board with it.

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  • \$\begingroup\$ Thanks for that! I'll try using the lower amp available from the power supply. Btw, I have a follow-up question, Is it okay to run 5v 2A power through a 10-12meters long zipcord wire? \$\endgroup\$
    – NF Squad
    Commented Nov 22, 2021 at 16:55
  • \$\begingroup\$ @NFSquad Depends on the gauge of the wire. Is zipcord wire the same as lamp cord? \$\endgroup\$
    – Hearth
    Commented Nov 22, 2021 at 16:57
  • \$\begingroup\$ Yeah zipcord is fine with 2A. The current through the wire will be only what the load uses (in your case the relays) so if all the relays are off it will be zero, don't mix up maximum power supply current with what your stuff will actually use. \$\endgroup\$
    – bobflux
    Commented Nov 22, 2021 at 16:57
  • \$\begingroup\$ well "zipcord" is not tightly specified, but yeah, the usual 1-1.5mm2 lamp cord will work fine. \$\endgroup\$
    – bobflux
    Commented Nov 22, 2021 at 16:58

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