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Old 09-06-2010, 12:43 PM   #16
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grounding the workpiece you're welding


Nap. I'm not misunderstanding the term. All I'm asking is: does the workpiece or metal table its on need to be grounded separate from the welder's work clamp. And does a metal piece resting on concrete constitute a ground. thanks


Last edited by jarnold; 09-06-2010 at 12:46 PM.
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Old 09-06-2010, 12:47 PM   #17
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grounding the workpiece you're welding


Quote:
Originally Posted by fabrk8r View Post

The welding circuit ground is totally independent from the power source. For the welding process to occur there has to be a complete circuit and this circuit has nothing to do with the "earth" ground in the power circuit.
yes, I am quite aware of that. The reason I said anything is you were speaking of putting the "ground clamp" close to your weld when working with GTAW welding.

Quote:
The best way is to attach the ground clamp directly to the workpiece. To expand on this, some welding processes, TIG for example, can best be performed if the ground clamp is in very close proximity to the electrode. This prevents a straying arc common with the TIG process.
the work clamp placement would be of concern for this but not the ground clamp. If things work well, the ground clamp should have no effects on the weld at all. It is only for the purpose of providing a 0 difference of potential between the work piece or table and any other conductor the operator might come into contact with. That 0 difference of potential will prevent current flow through the operator if he should contact both points at the same time.
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Old 09-06-2010, 12:49 PM   #18
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grounding the workpiece you're welding


jarnold, the concrete, or earth, will not constitute a "ground" as far the the welding circuit. You'll need to connect the actual ground clamp the the workpiece, or table.
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Old 09-06-2010, 12:51 PM   #19
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grounding the workpiece you're welding


Quote:
Originally Posted by jarnold View Post
Nap. I'm not misunderstanding the term. All I'm asking is: does the workpiece or metal table its on need to be grounded separate from the welder's work clamp. And does a metal piece resting on concrete constitute a ground. thanks
I didn't say you were, at least I don't recall where I did. Maybe I missed something I said to you but I do not believe I did.

Quote:
does the workpiece or metal table its on need to be grounded separate from the welder's work clamp
as stubbie provided, it should be.

Quote:
And does a metal piece resting on concrete constitute a ground.
not a dependable connection. When concrete is used as part of a grounding electrode in the NEC, it is only with metal being within the concrete and it is the metal that must be connected to.
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Old 09-06-2010, 12:53 PM   #20
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grounding the workpiece you're welding


Quote:
Originally Posted by fabrk8r View Post
jarnold, the concrete, or earth, will not constitute a "ground" as far the the welding circuit. You'll need to connect the actual ground clamp the the workpiece, or table.

not trying to start an argument but where have you ever seen a welder with a "ground clamp"?

the ground connection being referred to in this situation has nothing to do with the machine.
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Old 09-06-2010, 12:54 PM   #21
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grounding the workpiece you're welding


fabrk8r, Yes, I know the work clamp has to be clamped to the workpiece or table. But if you need to separately ground the workpiece for safety, does a workpiece connected to concrete constitute a ground.
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Old 09-06-2010, 12:56 PM   #22
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grounding the workpiece you're welding


nap, I know it seems like it shouldn't matter where the ground clamp is positioned, and for most welding processes it won't, but there is something about the GTAW, or TIG, process that will make the arc deflect under certain circumstances.

I fabricate a lot of stainless steel sinks and countertops and when welding where three surfaces meet it is almost impossible to control the direction of the arc unless the ground is positioned very close to the weld. An added advantage to this is that since there is little distance between the ground and the electrode it makes it less likely that my body will short the circuit and get a shock, which commonly happens in out-of-position welding.
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Old 09-06-2010, 12:58 PM   #23
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grounding the workpiece you're welding


nap, every welder I've ever seen has a ground clamp.

I'm sorry, I should have used more appropriate semantics...when I say ground clamp, I mean work clamp...I'm a fabricator, not an English teacher.


I apologize for the confusion. I know that all my fellow workers would look at me funny if I said "work clamp".
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Last edited by fabrk8r; 09-06-2010 at 01:03 PM. Reason: used wrong semantics
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Old 09-06-2010, 01:04 PM   #24
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grounding the workpiece you're welding


jarnold, there is no need for a separate ground.
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Old 09-06-2010, 01:09 PM   #25
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grounding the workpiece you're welding


Quote:
Originally Posted by fabrk8r View Post
nap, I know it seems like it shouldn't matter where the ground clamp is positioned, and for most welding processes it won't, but there is something about the GTAW, or TIG, process that will make the arc deflect under certain circumstances.

I fabricate a lot of stainless steel sinks and countertops and when welding where three surfaces it is almost impossible to control the direction of the arc unless the ground is positioned very close to the weld. An added advantage to this is that since there is little distance between the ground and the electrode it makes it less likely that my body will short the circuit and get a shock, which commonly happens in out-of-position welding.
but i ask again; have you actually seen a welder with a ground clamp?

it sounds like you are speaking of the work lead and I am not disagreeing with your points on that. I understand the process well enough to know what you are speaking of with the arc.

Quote:
But if you need to separately ground the workpiece for safety, does a workpiece connected to concrete constitute a ground.
no. while there will likely be some connection to ground through the concrete, simply setting on the concrete itself is not an acceptable grounding point or connection. When you are directed to connect the table to "ground", it is implied the "ground" is the building grounding electrode system or equipment grounding system. Concrete in itself is not part of that system. The intent is to provide a 0 difference of potential between any two points you might contact. Since the building power is providing the power to the welder, the only ground that would provide a safety factor would the the premises power source grounding system. The concrete of the floor is not part of that system by itself.
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Old 09-06-2010, 01:11 PM   #26
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grounding the workpiece you're welding


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Originally Posted by fabrk8r View Post
jarnold, there is no need for a separate ground.
you are incorrect. Stubbie presented contrasting information from a dependable source.

the fact you and friends are getting shocked proves why you do need an actual ground connection. That would prevent, or at least minimize, the shocks you are experiencing.
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Old 09-06-2010, 01:20 PM   #27
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grounding the workpiece you're welding


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Originally Posted by nap View Post
but i ask again; have you actually seen a welder with a ground clamp?
nap, yes, as I said every welder I've ever used, and I've used hundreds, had a ground clamp, or "work clamp" if you prefer.

Here is an example of an electrode holder, or stinger, on the left used for SMAW (shielded metal arc welding, or stick welding) and a common ground clamp on the right. Without either you'll have a hard time making a weld.
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Old 09-06-2010, 02:21 PM   #28
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grounding the workpiece you're welding


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=fabrk8r;496788]nap, yes, as I said every welder I've ever used, and I've used hundreds, had a ground clamp, or "work clamp" if you prefer.
that is the point and you even spoke to it as well. Technically it is not a ground clamp but a work clamp. This thread is dealing with actual grounding whether it be via a clamp or a permanent connection, which the work clamp does not provide. There should be (although I will admit it is rarely utilized from what I have seen) a ground connection to the work table and the work piece.

I cannot say I have ever seen a welder with an true ground clamp. (including the one you provided a picture of) .
Ground clamp is a commonly used misnomer used to indicate the work clamp.
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Old 09-06-2010, 04:23 PM   #29
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grounding the workpiece you're welding


sorry I had to run a few errands but when I returned I read thru my millermatic 225 manual and found this statement

Quote:
If earth grounding of the workpiece is required, ground it directly
with a separate cable
Now the question is ....When is earth grounding of the work piece required ?
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Old 09-06-2010, 04:48 PM   #30
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grounding the workpiece you're welding


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Originally Posted by Stubbie View Post
sorry I had to run a few errands but when I returned I read thru my millermatic 225 manual and found this statement

Now the question is ....When is earth grounding of the work piece required ?
well, I guess when ANSI standards are requrired to be followed:

Quote:
ANSI Z49.1, "Safety in Welding, Cutting and Allied Processes," the workpiece or the metal table that the workpiece rests upon must be grounded. We must connect the workpiece or work table to a suitable earth ground, such as a metal building frame. The ground connection should be independent or separate from the welding circuit connections.
btw, NEC 630.15 clearly states that the secondary of the welder shall not be considered as premises wiring fro the purpose of applying article 250 (Grounding and Bonding).

that would support your statement that the grounding must be separate of the work conductors.

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