Using Molex computer power connectors for mains?

[ledtester]

Related to my question about favorite wire to board connectors:

https://www.eevblog.com/forum/projects/favorite-wire-to-board-connectors-for-power/

I'm considering using the Molex power cables you find associated with ATX power supplies for carrying mains power from a power inlet to a PCB. Both the Molex Standard (0.093") and Molex Mini-fit Jr seem to be suitable for this purpose.




The advantages I see are (correct me if I'm wrong on any of these):

- pre-made cable assemblies using 20 - 18 AWG 300V wire
- Molex Standard pins and housings are spec-ed to 250V RMS and 9 A with similar specs for Mini-fit Jr
- pins can be extracted and inserted into alternate housings
- both male and female crimped wires in 8"+ lengths are readily (and cheaply) available

Are there any caveats I should be aware of? The intended application would be to supply mains power to a low voltage DC power supply / transformer, so the amount of mains current carried would be < 1A.

Update: I'm basing the Molex Standard specs on the information available on this Molex web page. I don't know the part number for the 4-pin housings used with computer power supplies, and perhaps they have different specs.

[Yansi]

Leave the 4-pin thingy to the PC stuff.

The Molex MiniFit (Amphenol MF42) 4.2mm pitch connectors are otherwise OK for mains applications. I would rather like to see 300V rating for these, but 250V may be good enough. have used those before. No fails reported.

[ajb]

I don't like those 4-pin connectors for mains because there's a slit in the plastic between adjacent contacts.  I'd want to leave an empty position between line and neutral.  The mini-fit ones are much preferable in that respect, being fully insulated.  A lot of unenclosed power supplies use three position JST VH or similar 3.56mm connectors with the center pin removed for mains input. 

The Molex MiniFit (Amphenol MF42) 4.2mm pitch connectors are otherwise OK for mains applications. I would rather like to see 300V rating for these, but 250V may be good enough. have used those before. No fails reported.

Often the ratings on connectors indicate which standard the manufacturer chose to test them against, not necessarily the levels at which they're safe to use, which is how you get otherwise identical connectors with different ratings depending on which certifying agency's logo is on it.  If there's a second source for equivalent components sometimes it's worth looking at their ratings to see if they're any different; this may give a better idea of what the connector geometry actually provides.  In some cases it may even be possible to get a manufacturer to re-test to a higher standard if the connector will support it.