<p>There's a few assumptions made:</p>
<ul>
<li>You are using RAMPS</li>
<li>You are factoring in maximum current draw (as one rightly should)</li>
<li>You use copper wires</li>
</ul>
<hr />
<h3>For a &quot;normal&quot; Arduino Mega and 12 V system</h3>
<p>From <a href="https://reprap.org/wiki/RAMPS_1.4#:%7E:text=The%2011%20amps%20pair%20is,on%20a%20RAMPS%201.4%20board.&amp;text=Your%20power%20supply%20should%20be,ok%20if%20it%20delivers%20more." rel="nofollow noreferrer">RAMPS 1.4</a>:</p>
<blockquote>
<p>The 11 amps pair is used to power the heated bed. The 5 amps source is used to power the board, the rest of the printer's components and the Arduino board.  Your power supply should be able to deliver 16 amps, is ok if it delivers more.</p>
</blockquote>
<p>You could use two different pairs of wires, as one pair only needs to supply 5 A and the other pair 11 A.</p>
<p><span class="math-container">$$P=IV$$</span>
<span class="math-container">$$P=5\times12$$</span>
<span class="math-container">$$P=60W$$</span>
and,
<span class="math-container">$$P=IV$$</span>
<span class="math-container">$$P=11\times12$$</span>
<span class="math-container">$$P=132W$$</span></p>
<p>From <a href="https://stex24.com/guide/cable-cross-section" rel="nofollow noreferrer">Calculate cable cross-section - Stecker Express</a></p>
<div class="s-table-container"><table class="s-table">
<thead>
<tr>
<th>Cable cross-sections for 24V applications with 3 metre cable length</th>
<th>Power in watts</th>
</tr>
</thead>
<tbody>
<tr>
<td>1.5 mm2</td>
<td>100</td>
</tr>
<tr>
<td>3 mm2</td>
<td>200</td>
</tr>
</tbody>
</table></div>
<p>or</p>
<div class="s-table-container"><table class="s-table">
<thead>
<tr>
<th>Cable cross-sections standardised in accordance with VDE 0295 for 12 V DC applications</th>
<th>Maximum current in amperes</th>
</tr>
</thead>
<tbody>
<tr>
<td>1.0 mm2</td>
<td>11</td>
</tr>
</tbody>
</table></div>
<p>So, for the 11 A wire, between 1 and 3 mm<sup>2</sup>. Which, from <a href="https://www.multicable.com/resources/reference-data/cross-reference-awg-to-mm2/" rel="nofollow noreferrer">Cross Reference AWG to MM2</a>, corresponds to 17 and 12 AWG.</p>
<p>For the 5 A wire, a 1.5 mm<sup>2</sup> cross-section would suffice. Which corresponds to 16 AWG.</p>
<h3>If you have a 24 V capable Arduino Mega clone and have a 24 V supply powering a modified RAMPS</h3>
<p>As per your previous question <a href="https://3dprinting.stackexchange.com/q/23656/4762">Would a 24 V/20 A PSU damage an Arduino Mega 2560?</a>, for a 24 V system...</p>
<p>Repeating the above, from <a href="https://reprap.org/wiki/RAMPS_1.4#:%7E:text=The%2011%20amps%20pair%20is,on%20a%20RAMPS%201.4%20board.&amp;text=Your%20power%20supply%20should%20be,ok%20if%20it%20delivers%20more." rel="nofollow noreferrer">RAMPS 1.4</a>:</p>
<blockquote>
<p>The 11 amps pair is used to power the heated bed. The 5 amps source is used to power the board, the rest of the printer's components and the Arduino board.  Your power supply should be able to deliver 16 amps, is ok if it delivers more.</p>
</blockquote>
<p>For the worst case scenario, the power will be</p>
<p><span class="math-container">$$P=IV$$</span>
<span class="math-container">$$P=16\times24$$</span>
<span class="math-container">$$P=368W$$</span></p>
<p>So, assuming that you use pure copper cables/wires, then the cross section <em>recommended</em> for 16 amps is, from <a href="https://www.spwales.com/cable-size-current-rating-chart" rel="nofollow noreferrer">Cable Size &amp; Current Rating Chart</a>:</p>
<div class="s-table-container"><table class="s-table">
<thead>
<tr>
<th>Cross Sectional Area of Conductor (mm2)</th>
<th>Approximate Overall Diameter of Insulated Cable (mm)</th>
<th>Current Rating</th>
</tr>
</thead>
<tbody>
<tr>
<td>(mm2)</td>
<td>(mm)</td>
<td>(A)</td>
</tr>
<tr>
<td>--</td>
<td>---</td>
<td>--</td>
</tr>
<tr>
<td>1.5</td>
<td>2.9</td>
<td>17.5</td>
</tr>
</tbody>
</table></div>
<p>From <a href="https://stex24.com/guide/cable-cross-section" rel="nofollow noreferrer">Calculate cable cross-section - Stecker Express</a></p>
<div class="s-table-container"><table class="s-table">
<thead>
<tr>
<th>Cable cross-sections for 24V applications with 3 metre cable length</th>
<th>Power in watts</th>
</tr>
</thead>
<tbody>
<tr>
<td>6</td>
<td>400</td>
</tr>
</tbody>
</table></div>
<p>or</p>
<div class="s-table-container"><table class="s-table">
<thead>
<tr>
<th>Cable cross-sections standardised in accordance with VDE 0295 for 12 V DC applications</th>
<th>Maximum current in amperes</th>
</tr>
</thead>
<tbody>
<tr>
<td>1.5 mm2</td>
<td>15</td>
</tr>
<tr>
<td>2.5 mm2</td>
<td>20</td>
</tr>
</tbody>
</table></div>
<p>So, let's say between 2.5 and 6 mm (which seems quite a variance, I must admit).</p>
<p>From <a href="https://www.multicable.com/resources/reference-data/cross-reference-awg-to-mm2/" rel="nofollow noreferrer">Cross Reference AWG to MM2</a>, cross-sections of 2.5 - 6 mm<sup>2</sup> correspond to 14 and 10 AWG, respectively.</p>

CC BY-SA 4.0
2024-10-06T21:37:47.877Z
16 Amps is what is rated for use in your house by electricians, so standard electrical wiring could be used, that is 2.5 mm^2
0scar
CC BY-SA 4.0
2024-10-06T21:40:20.403Z
Ah ok, so that is good. However, I assumed that it was a 24V system, and it isn't. Plus there are two different supplies and two different currents, so the wires could be thinner.
Greenonline
CC BY-SA 4.0
2024-10-06T21:51:21.533Z
Fixed it.. Added 12 V
Greenonline
CC BY-SA 4.0
2024-10-06T21:28:44.927Z
2024-10-06T21:50:53.563Z
2024-10-06T21:50:53.563Z
Greenonline
<p>I am building a 3D printer and need help on how to connect a 12 V 20 A PSU to my Arduino and what AWG wire to use for it.</p>

CC BY-SA 4.0
2024-10-06T13:31:18.340Z
This question is similar to: [Would a 24 V/20 A PSU damage an Arduino Mega 2560?](https://3dprinting.stackexchange.com/questions/23656/would-a-24-v-20-a-psu-damage-an-arduino-mega-2560). If you believe it’s different, please [edit] the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem.
agarza
CC BY-SA 4.0
2024-10-06T15:46:35.320Z
I don't understand the question. 0scar's answer already states that an Arduino Mega can take a 12 V input - so what is the problem? Or is the question just (more accurately put) "What AWG wire should I use?"
Greenonline
<diy-3d-printer><wire-type>
What AWG wire is suitable to connect PSU to Arduino Mega 2560
FrancisChristopher W
# What AWG wire is suitable to connect PSU to Arduino Mega 2560

(Asked by: username_0 on 2024-10-06)

I am building a 3D printer and need help on how to connect a 12 V 20 A PSU to my Arduino and what AWG wire to use for it.

**Tags:** diy-3d-printer, wire-type

> **Comments:**
> **username_1**: This question is similar to: [Would a 24 V/20 A PSU damage an Arduino Mega 2560?](https://3dprinting.stackexchange.com/questions/23656/would-a-24-v-20-a-psu-damage-an-arduino-mega-2560). If you believe it’s different, please [edit] the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem.  
> **username_2**: I don't understand the question. username_3's answer already states that an Arduino Mega can take a 12 V input - so what is the problem? Or is the question just (more accurately put) "What AWG wire should I use?"  

---

## 1 answers

### Answer by username_2 on 2024-10-06. Score: 2

There's a few assumptions made:

* You are using RAMPS
* You are factoring in maximum current draw (as one rightly should)
* You use copper wires

---

### For a "normal" Arduino Mega and 12 V system

From [RAMPS 1.4](https://reprap.org/wiki/RAMPS_1.4#:%7E:text=The%2011%20amps%20pair%20is,on%20a%20RAMPS%201.4%20board.&text=Your%20power%20supply%20should%20be,ok%20if%20it%20delivers%20more.):

> The 11 amps pair is used to power the heated bed. The 5 amps source is used to power the board, the rest of the printer's components and the Arduino board. Your power supply should be able to deliver 16 amps, is ok if it delivers more.

You could use two different pairs of wires, as one pair only needs to supply 5 A and the other pair 11 A.

$$P=IV$$
$$P=5\times12$$
$$P=60W$$
and,
$$P=IV$$
$$P=11\times12$$
$$P=132W$$

From [Calculate cable cross-section - Stecker Express](https://stex24.com/guide/cable-cross-section)

| Cable cross-sections for 24V applications with 3 metre cable length | Power in watts |
| --- | --- |
| 1.5 mm2 | 100 |
| 3 mm2 | 200 |

or

| Cable cross-sections standardised in accordance with VDE 0295 for 12 V DC applications | Maximum current in amperes |
| --- | --- |
| 1.0 mm2 | 11 |

So, for the 11 A wire, between 1 and 3 mm2. Which, from [Cross Reference AWG to MM2](https://www.multicable.com/resources/reference-data/cross-reference-awg-to-mm2/), corresponds to 17 and 12 AWG.

For the 5 A wire, a 1.5 mm2 cross-section would suffice. Which corresponds to 16 AWG.

### If you have a 24 V capable Arduino Mega clone and have a 24 V supply powering a modified RAMPS

As per your previous question [Would a 24 V/20 A PSU damage an Arduino Mega 2560?](https://3dprinting.stackexchange.com/q/23656/4762), for a 24 V system...

Repeating the above, from [RAMPS 1.4](https://reprap.org/wiki/RAMPS_1.4#:%7E:text=The%2011%20amps%20pair%20is,on%20a%20RAMPS%201.4%20board.&text=Your%20power%20supply%20should%20be,ok%20if%20it%20delivers%20more.):

> The 11 amps pair is used to power the heated bed. The 5 amps source is used to power the board, the rest of the printer's components and the Arduino board. Your power supply should be able to deliver 16 amps, is ok if it delivers more.

For the worst case scenario, the power will be

$$P=IV$$
$$P=16\times24$$
$$P=368W$$

So, assuming that you use pure copper cables/wires, then the cross section *recommended* for 16 amps is, from [Cable Size & Current Rating Chart](https://www.spwales.com/cable-size-current-rating-chart):

| Cross Sectional Area of Conductor (mm2) | Approximate Overall Diameter of Insulated Cable (mm) | Current Rating |
| --- | --- | --- |
| (mm2) | (mm) | (A) |
| -- | --- | -- |
| 1.5 | 2.9 | 17.5 |

From [Calculate cable cross-section - Stecker Express](https://stex24.com/guide/cable-cross-section)

| Cable cross-sections for 24V applications with 3 metre cable length | Power in watts |
| --- | --- |
| 6 | 400 |

or

| Cable cross-sections standardised in accordance with VDE 0295 for 12 V DC applications | Maximum current in amperes |
| --- | --- |
| 1.5 mm2 | 15 |
| 2.5 mm2 | 20 |

So, let's say between 2.5 and 6 mm (which seems quite a variance, I must admit).

From [Cross Reference AWG to MM2](https://www.multicable.com/resources/reference-data/cross-reference-awg-to-mm2/), cross-sections of 2.5 - 6 mm2 correspond to 14 and 10 AWG, respectively.

> **Comments:**
> **username_3**: 16 Amps is what is rated for use in your house by electricians, so standard electrical wiring could be used, that is 2.5 mm^2  
> **username_2**: Ah ok, so that is good. However, I assumed that it was a 24V system, and it isn't. Plus there are two different supplies and two different currents, so the wires could be thinner.  
> **username_2**: Fixed it.. Added 12 V  

---

