I'm looking to power a Prusia i3 3D printer with RAMPS 1.4 from an eTopxizu Dc 30A 360 W Regulated Switching Power Supply, at the moment I'm looking at how to connect it (safely) to a United States wall outlet.

I've seen that you can cut off the female end of a standard power cable for a PC and strip the insulation to reveal three insulated: wires, ground, positive and minus respectively.

And then those would be connected to a spade electrical connector which has a rating for a particular kind of wire.

(And yes, I know this would likely be the last step in the process after wiring everything up before plugging it in, and safety dictates that I NEVER NEVER touch the leads when it is plugged in; I plan to cover the back end of the device with a 3D printed cover and a switch so nobody touches the leads.)

But my question is, that given the type of wire I intend to use to connect it to the US outlet, what sort of rating should the spade connectors have?

  • \$\begingroup\$ it might be a better idea to get a socket that matches the end of the computer cable \$\endgroup\$ Jan 3, 2016 at 22:17
  • \$\begingroup\$ Your wire will have a diameter, often denoted with AWG. A plug for the same AWG should have the same current rating as the wire you're using. Other than that, Transistor adds a valid point about a fuse. As a point of order, the outlet has no positive or minus, but a Phase/Live and Neutral, or two Live wires in a US 240V socket. Positive and Negative are "DC" words that intend to denote a fixed direction of current flow, whereas a Mains socket has AC, where it flows in both directions, alternating. \$\endgroup\$
    – Asmyldof
    Jan 3, 2016 at 22:18
  • \$\begingroup\$ What does the manufacturer say? \$\endgroup\$
    – Andy aka
    Jan 4, 2016 at 9:40
  • \$\begingroup\$ Down vote; okay well I'm pretty new at this. \$\endgroup\$
    – leeand00
    Jan 6, 2016 at 14:29

1 Answer 1


360 W at 120 V will draw 3 A on full load. (From P = V * I)

Connect with an inline fuse in the L wire and make sure you connect the earth / ground lead.

Any forked or ring terminals that fit that size screw are likely rated for 3 A or more. If all the strands of your mains lead wires fit inside the crimp barrel it's a good sign that all is well.

  • \$\begingroup\$ I believe the fuses are already on the RAMPS 1.4 where you connect them to the power supply. \$\endgroup\$
    – leeand00
    Jan 3, 2016 at 23:13

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