[Quada]

Just finalizing the setup on my pieced-together CNC router. I am using the following components:

Gecko G540 Controller
Hitachi WJ200 2.2kW VFD
Chinese 2.2kW Spindle

I took apart the Chinese spindle and connected pin 4 to the body of the spindle which goes to earth on the VFD. I am going to wire up my touch plate to one of the homing inputs on the G540 and for the touch plate to work, I need to complete a ground loop from the ground of my 48VDC power supply (powered from 110VAC) and the earth of the 220V line.

Will there be any problems connecting the earth of my 220V line to the ground/neutral of my 110V line? I would assume I can't do this, so how have others wired up a touch plate when dealing with a grounded Chinese spindle?

[Al_The_Man]

Yes you can connect to any ground conductor, normally you would set up a star point ground in the enclosure etc where all earth ground references go to, including the service ground conductor.
Make sure any metallic parts of the table or the gantry is bonded to earth ground.
Al,

[Quada]

So it is safe for me to connect 110V neutral to earth? I don't think this is up to code. Is there an alternative that meets US electric code requirements?

[Al_The_Man]

The neutral should be connected to earth ground at the service panel and this is the ONLY place that earth ground should be connected to neutral, NEC code.
The exception is if you provide a separate isolated 120v supply from a control transformer secondary, in this case you can re-reference one side of the secondary to earth ground at one point only at the terminal of the transformer.
Al.

[alan_3301]

The 120V Neutral should only go to your power supply, Use the ground for grounding.
There is no need to complete a ground loop, that implies you already have ground everywhere it is needed, and you are just connecting it together, redundantly.

[Al_The_Man]

Here is a little more on ground bonding.
http://www.automation.siemens.com/do.../emv_r.pdf?p=1
Al.

[Quada]

See attached for a better understanding of what I am questioning. Can I safely add the highlighted jumper?

[alan_3301]

I think you may find that connection is already there inside the DC power supply, but I don't think it would hurt anything to add it.

And I think it's confusing to call it neutral on the 220 lines, I think usually it is referred to as L1 and L2

[Al_The_Man]

The confusion comes from some VFD's that are labelled with a N alongside one of the R S T supply inputs where 3 ph or 1 ph 220 is the supply, this caters to places such as Europe where the 240v supply is L1 & N.
In N.America the neutral is not generally used on a VFD, unless it is a 120v type VFD.
Al.

[Quada]

Yes it should be labeled L1 and L2 on the 220V line, I just copied and pasted with the intention of changing it but I guess I didn't. I can take a multimeter to the power supply tonight and check if the -48V (ground) line actually makes contact with the earth on the power supply input.

[Quada]

Just checked the DC power supply; there is no connection between the -48V and the ground. Surely I can't be the first one to run into this dilemma?

[Al_The_Man]

Most of the systems I have implemented I have made all the power supplies -ve common to earth ground with no problems.
Al.