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I have a requirement where I need to control around 20 solenoids which is housed separate from a Raspberry pi, ATX PSU and veroboard containing my logic circuit. For convenience I will call them CASE-A and CASE-B.

The solenoid requires 0.5A@12VDC and the pump requires 3A@12VDC. This will require me to transfer about 13A between CASE-A & CASE-B. I need the connections to be modular so that I can pull the cases apart for troubleshooting/maintenance.

Can I use the standard ATX 24-pin connector ? (something like this--http://www.amazon.com/29-5cm-Computer-Female-Extension-Power/dp/B00EZ50W36/)

I can see the following way to connect them up, (a) In CASE-A, connect one leg of each solenoid and the postitive lead of the pump to one wire of the ATX 24-pin cable. In CASE-B, connect the other end pin to the +12V lead in the ATX PSU.

(b) In CASE-A, run a separate wire from the other leg of each solenoid and the negative lead of the pump to separate wires of ATX 24-pin cable(21 wires). In CASE-B, connect the other end pins to my veroboard logic circuit (the circuit would then complete the connection to ground depending upon logic controlled by the RPI).

Will the standard ATX 24-pin connector be able to handle the load?

Is there a different way?

Thanks Vijay PS: Veroboard logic will be similar to Will this schematic work?, however instead of 5 pumps there will be one pump and 20 solenoids.

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  • \$\begingroup\$ The entire connector, yes. A single pin? Doubt it. It's 18 to 16 awg. \$\endgroup\$ – Passerby Sep 10 '15 at 13:35
  • \$\begingroup\$ Do you suggest I go with two 24-pin connectors to spread the load across? How much can one pin handle? \$\endgroup\$ – Vijay Seshan Sep 10 '15 at 13:46
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    \$\begingroup\$ You need 150 Watts. A single 24 pin connector can do that. A single wire would not. \$\endgroup\$ – Passerby Sep 10 '15 at 13:54
  • \$\begingroup\$ Also given how little experience you seem to have with these things, I hope you have considered the current carrying capacity of your PCB traces as well. \$\endgroup\$ – Fizz Sep 10 '15 at 16:18
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The datasheet (it's a great thing to find such details) of the connector tells us:

Current = 13A max. per circuit when header is mated to a receptacle loaded with 45750 Mini-Fit® Plus HCS Crimp Terminal Crimped to 16 AWG wire., See Molex product specification PS-45750-001 for additional current de-rating information.

The advice of Molex in their additional product specification actually shows, that on a fully populated 24 pin Wire-To-Board connector, the rated current is decreased to 8A per pin:

rated currents for different connector styles and wires

I wouldn't go anywhere near the maximum on a single pin though, at that current they will get hot (specified to a temperature rise of 30K above ambient at rated current).

So if you spread out the load over several of the 24 pins, you should be fine.

A low quality connector might not hold up to those specs - another reason why not to go to the limits.

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