Hello, just joined to this forum.
I have a question regarding connecting the DC output "-" of an SMPS to the mains earth ground.
Normally majority of the consumer SMPS units are floating in respect to the DC output side. That mostly includes plastic enclosed "wall wart" type of adaptors. Besides that majority of other SMPS types are also floating including the metal enclosed specialty units. However the latter breed has the earth ground terminal provided on the terminal block and that terminal is connected to the SMPS chassis as well. Here I'm talking about the well known Mean Well line of the metal enclosed SMPSs like this one:
https://www.meanwell-web.com/en-gb/ac-dc-single-output-enclosed-power-supply-lrs--50--12

My direct question is: Can I provide the mains earth ground to the DC output, connecting the mains earth ground to the "-" of the DC output of the SMPS?
The second question is - are there any downsides and possibly negative effects associated with connecting the DC "-" to the earth ground?

The reason I want to have the DC output of the SMPS ground referenced is to avoid leakage current rom the SMPS to damage sensitive circuits and components like MOSFETs in certain conditions. For instance, I damaged a few power MOSFETs when using a floating SMPS and wearing the ESD wrist strap at the same time. I understand that if the DC "-" of my SMPS was ground referenced I would avoid that king of damage.

 

Grounding the Negative output helps with interference suppression and radio interference, it also ensures that any added modules that are connected are also grounded, like usbs, video cards etc.

 

Many of the metal enclosed SMPS DC units that have a GND terminal is where ground referenced suppression caps are connected to, no other connections to the circuit, best to confirm individual units.

 

Prior to making a solid connection between the SMPS negative output terminal and "actual earth ground." I suggest measuring the voltage between those two points. That will reveal if there would be a problem. That is as cheap and easy as Ican make it, and if there is a constant voltage it still might be OK.

 

Thank you for your replies so far. However judging by the last two posts I have a feeling that while it sounds as easy as bringing the SMPS DC output "common" (I assume "-" here for simplicity) down to the earth ground level, in reality there are some more things involved that may prohibit such an innocent connection of DC"-" to GND.
If possible please elaborate on the subject.

 

Can you be more specific. What is this SMPS supposed to do? What us the application? What are requirements?

If the SMPS is isolated, you are free to connect either negative or positive terminal to almost anything. Some devices are bot isolated. An example of this is desktop PC power supply.
Small power supplies tend to be double isolated so in this case grounding output is not required

In industry power supplies can get large. Some are fed by 3ph power. Here that means 480 or 600VAC. output can be low, such as 24VDC. But if there is a failure, it could be possible that mains voltage appears at the output. This is the same as with faulty transformer where secondary is floating. And it is common that safety standards may require grounding such output.

So... Before we write 1000 pages on what can and cannot happen or may or nay not aoply, why don't you try explaining your exact case?

 

So... Before we write 1000 pages on what can and cannot happen or may or nay not aoply, why don't you try explaining your exact case?

Before you write 1000 pages of what you were about to write could you please read the last paragraph of my original post?

 

point taken...

and the answer is yes. this is a proper AC/DC PSU so output is isolated. you can connect negative terminal to GND (or positive if you like... just do not connect them both at the same time).