Tying 24VDC- to Ground

[cntrlfrk]

What are your opinions on grounding the 24VDC- to ground in a control cabinet? I've always done it, this latest place I'm working they thought I was nuts when I did it.

Any advantages or disadvantages?

[marksji]

I'm sure I'll get nailed for this as its not the generally accepted "correct" method, but its what my experience has led me to do...

In my opinion you're better off leaving it floating because then you know your 24vdc power is clean.

I know that virtually every time I've tried connecting 24vdc- to ground I've created some sort of problem for myself...

[gphillips]

I have never grounded 24 vdc and never experienced any problems. The power supplies I use don't have a ground terminal on the dc output side so I figured it wasn't necessary.

[tomalbright]

My current project, because of the way we had to wire, I grounded the negative to the cabinet.

Another reason to do so is for troubleshooting; it's easier to find out where your voltage is going when you can reference it to ground. I'm working on offshore projects; typically everything is referenced to the frame as a ground anyway.

[Jim Dungar]

I ground all of mine. But, I have a very hard time calling this reference -24VDC like most people do, I prefer 0V. also, I have started to use conductor insulation of white with a blue stripe.

[rdrast]

I never leave any supply floating unless it is absolutely required by the attached devices.
In all of my panels, all control reference legs (115VAC Neutral, 24VDC 0V, 12VDC 0V, 5VDC 0V, are all tied to earth. I've never had a problem.

[Rube]

I never ground my 24 but I also don't work with anything other than inputs that use 24.

[504bloke]

Originally Posted by rdrast

I never leave any supply floating unless it is absolutely required by the attached devices.
In all of my panels, all control reference legs (115VAC Neutral, 24VDC 0V, 12VDC 0V, 5VDC 0V, are all tied to earth. I've never had a problem.

Same as me

[Steve Kemp]

Crntlfrk, you're not alone:

Poll: 24 Volt Inputs and Grounds
Steve.

Sorry, that should be cntrlfrk...

[TConnolly]

I also ground by 24V power supplies and I also call it 0DC not -24Vdc because it is not -24Vdc. I also use a white wire with a blue trace.


Note: even though the AC Neutral and 24V are both bonded to ground keep the neutral and the 0vdc buss seperated each with an independent ground.

[russrmartin]

Marksji,

Just out of curiosity, what problems have you caused for yourself?

[marksji]

Most of the time its from noise caused by ignition transformers, but sometimes its noise that already existed on the ground.

[russrmartin]

Wouldn't that indicate a ground problem at your site? Not trying to be a smartass here, electrical systems design is not my area of expertise. But if grounding a voltage cause noise on a system, my inclination and little experience would tempt me to look at my ground system more. Is ground noise a common problem that is accepted or not usually remedied? Thanks.

Russ

[marksji]

Originally Posted by russrmartin

Wouldn't that indicate a ground problem at your site? Not trying to be a smartass here, electrical systems design is not my area of expertise. But if grounding a voltage cause noise on a system, my inclination and little experience would tempt me to look at my ground system more. Is ground noise a common problem that is accepted or not usually remedied? Thanks.
Russ

Yes, I would assume so, but I have no control over the electrical system at any individual customer site so I have to build my machines to make do with what they've got. There was a time not too long ago when actually getting a ground wire pulled to the machine was rather remarkable.

[rstech]

I always ground the common (negative if you will) of my power supplies. Never had a problem. As others mentioned, I also use blue with white stripe for the DC common.