Never smaller .Larger ok.
Hi,
at the moment I'm building the control panel and could need a little help with the size of the ground wires.
The source wire is 1,5mm^2. All consumers are internal connected to a star point. Would it be a problem if the consumers ground wires to the star point are thicker (2,5mm^2) than the input source ground wire or is it necessary that the wires to the star point are smaller than the source wire?
Here are some pictures: (In the future all ground wires will go to ground temrinal blocks on a rail..)
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Never smaller .Larger ok.
Ok. Thanks. Another question:
As you can see on the picture the panel has three line-in wires. Each one with hot/neutral/ground.
I would like to crimp their grounds together and use them like one large ground wire. Is this a problem?
The Ground wire should be the same gauge as the supply conductor or same as the combined size, if supply is from difference sources.
All ground wires should terminate at the star point or be joined and continued with a single conductor equal to the combined gauges.
The service ground should also terminate at the Star Point GND.
There was a copy of NFPA79 out there if needing guidance on regs for enclosure wiring.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
This is a good question, so if other devices require or have a larger Ground wire, this could indicate that your main supply is to small 1.5mm is only 15 Gauge ( close enough to 16 Gauge ) most cabinet's need at least a 30A supply which would be 10 Gauge, so I would say you input supply is a little on the light side
What size is the VFD Drive ??? this will need a Power Filter on it input supply
The Mains Power Supply Ground Connects at the Star Point
Mactec54
Thanks for the feedback.
The first power input is for the 5v and 12v power supplies and maybe for other stuff in the future like a vacuum cleaner etc. And it is connected to a contactor that switches on the other two inputs ( one for the steppers and one for the spindle ). Normally I would have used 3-phase current for this but I don't have the possibilities for this.
@mactec54
The consumers don't need 2,5mm^2. I just used it for them.
We routinely build control panels for production lines with multiple power sources and grounds. They are all sourced from the building main 13.8 Kv and substations. All grounds are tied back to the main substation. It makes no difference. Your control panel needs a disconnect for each source.
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
One example is DIN rail mount terminals, you can get them with automatic ground to the enclosure, they are half green, half yellow, and are intended for such cables that also include a ground conductor.
The ground in this instance is through enclosure bonding, but also pays to take a single correctly sized one to the star point also.
This is the method I have used for over 50yrs.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Not the same. I installed and wired production lines, moved old junk machines at times into the modern world. Plus new stuff also, some PLCs. some solid state control systems as prototypes and just a lot of MCC wiring to machines and tying in interlocks and the like. At the time I was working under a very strict Master Electrician. Later on I was the sole electrician for second shift production. Loved every minute of my electrical work. Later got into Commercial HVAC/R work specialized in controls.
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
This is it now:
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
@mactec54
As far as I know those 2.2kw + VFD sets won't exceed 8A.
@al_the_man
Just added them yesterday to replace the messy wiring with the enclosures ground pin. Not a beauty but it's still a work in progress.