What is the amperage rating of the Molex Connector?

I am using a fan hub that is powered by Molex, which is connected towards my PSU. I would like to know how much amps can the Molex handle (and hence, would also determine the ampacity of the fan hub). Wikipedia says its 11A/pin but Molex has 4 pins, so does that mean it has an ampacity of 44A?

Solution 1:

From referenced Wikipedia page:

Max. current 11 A/pin (18AWG w/30 °C rise)

So 4 pins at 11A/pin leads to the 44A of OP. The problem is a little bit more complicated than that.

The maximum current that can be carried is a function of the maximum temperature of the housing (105°C) and the maximum temperature of individual connection (30°C) (and maximum temperature of wire insulation) (and length of wire) (and ambient temperature). More wires, the less total current.

From Tyco data sheet for Amp connectors.

Table shows number of circuits vs size of wire. Larger wire = more current. Less wires = more current. Derating connector due to adjacent conductors.

The wiki page is wrong (and right). With every circuit energized, for a 4 in-line connector, with 18 AWG wire is 9A/pin. 36A per connector theoretical maximum, if 105°C and 30°C are maintained. That is 18A supplied and 18A sunk (Ground).

As Tyco says:

...are intended to be a guide in the selection of a connector family. All applications should be tested by the end user.

As in designer is responsibe. There are other factors: Ambient Temperature. Insulation on wire. Wire length. Odds are that no actual circuit will have 18A sourced due to other factors.

Increase wire size to 14 AWG and you do get 11A/pin. And OP 44A/connector.

From SuperUser (but no reference to external source) Is this a floppy disk connector to the power supply?:

With the 14 AWG cable, you could get 11A on 12V circuit (Pins 1 and 2), 132W, and 11A on 5V circuit (Pins 3 and 4), 55W. Assuming power supply could source it.

Typically, power supplies supplied half that for peripherals (5A for both comes to mind). You try to avoid theoretical maximums for production.

A good reference on connector capabilities: All about the various PC power supply cables and connectors