“Ground”, I hear this term a lot on all the forums welding, automotive, etc. and a lot of the time its not used in the proper context.
I am not going into all the technical terms of what, when and why but this should help people understand.
Electric systems AC uses a ground you have power wires and ground wires. If for some reason you lose your ground you lose your power.
DC power systems use positive and negative there is no ground. Like the battery in your car or truck lose the positive or negative its dead won’t start or nothing in it will work.
Now as far as welders and plasma cutters there is a ground. The ground is on the inside and is used to ground everything from the case, PCB,s, etc. to the AC power system.
The cable with the clamp on it that you put on the metal to be welder or cut is “NOT” a ground. It is the work cable and clamp, it goes to the work piece (metal). The work cable and clamp can be positive or negative depending on the process being used as DCEP or DCEN.
Now it is recommend by a lot of welding and plasma cutter makers to ground the unit to the welding table or cutting table this is done with a wire say 10 gauge or what ever is recommend in the manual from the unit case screw or ground terminal to the table or even the the building if its metal.
I know we all have been using the word ground. But the next time you may thing about what you really mean when say did you “GROUND” it.
Interesting technical perspective. As an Electrical Engineer by training I am aware of the technical argument.
But you’re arguing conventional useage - like Xerox copies for any photocopier produced document duplicate, or Kleenex for any facial tissue, or gas instead of gasoline.
None of the above are generally the technically correct term but everyone understands what you mean. Language is about communication and the technical inaccuracies help communication while a blind insistence on technical accuracy of the language can get in the way of the intended objective of communicating.
This is the case here. You’ll find the “work clamp” identified as the “ground clamp” if you Google parts for your welder or plasma cutter. You’ll find the term “ground clamp” or “earth clamp” in the manual for your welder or plasma cutter for the device you’re calling the “work clamp”.
So technically you’re correct but it’s an abstract correctness that doesn’t really do much good - if someone asks their dealer for a replacement ground clamp they’ll be given the correct part
With Plasma cutting the work cable or work clamp is always the positive side of the DC circuit that produces a high temperature plasma arc. The negative output from the DC power supply is connected directly to the electrode inside the torch, positive to the Workpiece (the metal you are cutting.) Hypertherm has been producing plasma cutting systems since 1968, and the work cable and work clamp have never been called a ground. When you order replacement parts you order a work cable or work clamp. Many of the (mostly low cost import) plasma cutters on the market today will call this work cable a ground cable…only because they do not understand the correct terminology as the sellers and distributors do not actually design and build plasma cutters from the ground up. Jim Colt
In an AC branch circuit, when you lose the ground you will still have “power”. The “hot” and “neutral” are the ones that supply and carry the power/current. The “ground” does not carry current/power and is not supposed to.
In a transmission circuit, if you lose ground you will still have power but nothing to reference the voltage to.
Prior to receiving my Hypertherm 30 Air, I had the garage completely wired for my welding and grinding needs. I had about a dozen 20 amp outlets installed along with 2 30 amp and 1 50 amp outlets for my welding, etc. I do not have any “ground” wires connected to “earth” or otherwise. I have been assuming that the electrical installation was sufficient for my needs. The work was done by a reuputable electrical contractor and permitted and inspected by the city.
Being a ham radio operator (but not having practiced for years), I do know the importance of grounding mainly for RF.
Am I endangering myself or others by using my system as described? I have been cutting hundreds of pieces with a water table (hands in the water fishing out popups ) without any thought of electrocution.
Dennis, are you saying that even on the 120 outlets there is no bare copper wire landed to the “green screw”? Did they not use standard Romex residential conductor in your build?
If it was to code (& since it was done by a licensed installer & permitted/signed off it is reasonable to assume it was), then you have a ground from the outlet to the panel and then from there to the main house ground - usually a 10’ copper rod driven into the earth outside the house although some areas use(d) grounding via water pipes.
There likely won’t be a separate ground outside the garage for the wiring in the garage. It all routes through the green wire in the walls to the panel.
Good. I am always hearing about having the table/cutter grounded as if I were required to add additional grounding to the system. Thanks for the clarification.
Nope, you’re good. People who have wiring issues may have bad grounds but that will apply to their whole house/shop. Or they bypass the ground for the Crossfire control unit by using one of those two prong adapters that allow you to plug a 3-prong cable into a 2-prong extension cord.
You’re probably in better shape than most since you had things fully rewired for both 110 & 240V.
Personally I’m jealous - I never have enough outlets or the right/enough power
Grounding (what we call bonding) the copper water line is not meant to ground the electrical system of a house but is to keep current from entering the water and copper lines. Lighting strike for example. In most cases, where I live and with newer homes, the water line entering the house is plastic. Older homes have a copper line from the street.
Nowadays, the water line gets bonded before and after any serviceable part when the water line enters the house. The natural gas line gets bonded before and after the meter and the rebar in the foundation also gets bonded/grounded.
@doleslie if you do not have any grounds in the outlets that were added then I recommend getting them asap.
The ground is there for your protection. Let’s say you are using a plasma machine and a hot wire inside the machine works it way lose and touches the case. Any thing conductive touching the metal case will now be live and can shock the crap right out of you.
If the outlet was grounded and the same thing happened then the breaker would trip and protect you from getting shocked.
I’ve once went on aservice call back when I did electric that I still remember like it was yesterday. The family would get shocked everytime they used the stove and touched the pan and/or the metal part of the stove. After some troubleshooting I found that a wire had melted inside of the stove and came into contact with the metal case and the person who installed the stove did not hook up the ground inside of the stove, only the neutral. It was a newer 4 wire stove that was wired to a 3 wire plug. I told them they were lucky to be standing there talking to me.
Now some tools will not have a ground prong (3 prong). Only a hot and a neutral (2 prong). This is because the device is double insulated.
Yeah, I grew up in a house built in 1901. They had the “newfangled” electric installed when they built it. Probably 4 electrical renovations before we finally sold it after my mother’s death.
Every time we had it redone, we’d shake our heads at what had passed for “safe & appropriate” the time before. It wasn’t until the last one we got 3-conductor wiring and grounded outlets Even then, they didn’t have the ground rod they put in my house when I built it 10 years later.
We did dodge the whole aluminum wiring fiasco that was code for awhile until it turned out to be prone to brittleness and fires.
I avoid aluminum wire at all cost. The connections loosen over time and not to mention oxidation. And the noalox use to prevent oxidation is like glitter. It gets everywhere and won’t come off! Although that stuff is fun when playing pranks on fellow workers.
So as I understand this, I am awaiting My Crossfire pro with THC, and I will be using a New unboxed , Thermal Dynamics cutmaster 39 I bought years ago as a backup… Anyways I just opened the box and pulled the cover off to see for a RAW POWER connection to the THC what I need to do. I see the BLACK wire to the torch connects to the Output on the circut board and the CLAMP goes to a seperate area… so RAW POWER would be connected Black to Output to torch and to Clamp Correct… It does have a red wire from torch connection that goes to Pilot
Arc voltage height control has to monitor the arc voltage (also known as load voltage or cutting voltage). Arc Voltage on any plasma system can be measured between the torch electrode (which is negative) and the work cable (cable with clamp that goes to the material being cut) which is positive. I don’t recommend guessing which wires as this voltage can reach 300 VDC, so you should look at the wiring diagram for the Thermal Dynamics system and determine the best connections for negative and positive inside the power supply…trace the connections back from the torch electrode and the work clamp to good screw terminal connections, usually on the main power board. Ensure also that the height control you are using is compatible with Raw Arc Voltage, as most THC systems use a divided voltage, often 1/50th of the raw arc voltage for safety reasons. Some newer T-D units have a divided voltage output…though probably not the older Cutmaster 39. Run the raw voltage wiring correctly (at least 300 volt insulation) and safely as (again) this is high voltage. Jim Colt
The Langmuir THC supports both. In fact that’s why it’s being held up right now - the box that allows connection to either raw or divided voltage is sitting in a warehouse in China waiting for people to be allowed to load them onto the truck. Coronovirus embargoes taking its toll.
