PSU Dummy load question

[selfdestroyer]

I have a feeling I should have listened more in math class. I'm lost on this and the reading I have done makes my head hurt.

I have a Mean Well RQ-125B switching power supply that according to the datasheet it needs 2A load on the 5V for it to operate correctly. It goes into a protection mode if there is no load on the 5V and will keep the power supply from turning on. Unfortunately, I do not need the 5V rail currently and need to put a dummy load on it to use the +12 and -12 portion for the PSU. It was suggested by someone to put a "Chassis Mount 10watts 2.5ohms Wirewound Resistor" on the 5V and COM GND to achieve the dummy load.

I have used a few other Mean Well PSUs and none of them needed such a high load on the 5V so this is a first for me.

I hooked up the wirewound resistor and the PSU fires up with out issue. I busted out the DMM and all the terminals are outputting the proper voltage but... the wirewound resistor gets VERY hot. Like beyond touch and it even smells hot. The guy that suggested this resistor said it was normal for these to get extremely hot but I have no experience with these and would like some feedback from others. I currently have no fan inside the case that houses the PCU but its very spacious and has air holes. I attached the wirewound resistor to the top of the PSU to make the case of the PSU act as a large heat sink.

PSU datasheet:
https://www.mouser.com/datasheet/2/260/RQ-125-SPEC-1291758.pdf

Wirewound Resistor I used:
https://www.mouser.com/ProductDetail/71-RE65G2R50

Am I using the right resistor? Is the heat really an issue? Will my case catch fire while I'm making music and becoming a spectacle that people will not soon forget?

-Cody

[somnif]

Well 5V at 2amp is 10W, so that rating should handle things. Rated to 250C, heatsink package, should handle playing space heater fine....

The electrolytics in the PSU look like they're rated for 105C, so thats a bit lower...

And the PSU starts to drop in efficiency above 50C, and seems to cut out entirely at 70C....

So, in short... I have no idea! 

[Aristatertotle]

I would be wary of running the resistor at full rating for a long time, especially if it's mounted to the mean well psu. In the datasheet it says that the rated wattage is if it's attached to 4 x 6 x 2 x .04 inch aluminum enclosure, and the PSU is pretty close to those dimensions, but if it's steel or painting, it might not be enough. If it's bare aluminum it might not be making good enough contact to the case because of the ventilation holes.

I would get a 2.5 ohm 20 watt one and have it mounted to an actual heatsink or a decently thick aluminum bracket (say 1/8") to act as a heatsink. I've done something similar for tube amp head dummy loads.

[nzCdog]

When I was building a speaker load I used panel mount resistors I could heatsink easily to the enclosure. A quick search at RS and here's a cheap 5ohm 25W. You could do 2in parallel and have plenty of derating headroom.

https://nz.rs-online.com/mobile/p/panel-mount-fixed-resistors/0158503/

[selfdestroyer]

Thanks for the replies people. I think since the rating of the wirewound is 482 degrees F I think I'm over reacting about how hot its getting. I think I will take Aristatertotle's advice and do an aluminum angle bracket for use of a heat sink.