Some help with grounding my welding table (Ideas please)

[cybordolphin]

I would like to ground my welding table (not just make it part of the weld circuit).

Please post your ideas and or pics of how you have your weld table grounded.

I am going to be welding in a solid concrete and cinder block enclosure (with windows). I can't easily drive a ground rod and tie to that. And I have no water pipes nearby. What other ways are there? I might be able to use a ground from the building circuit, but that is also the same ground as the weld circuit I believe.... so that might negate the whole idea/purpose.

The weld table is on wheels and I don't believe they conduct electricity. Thus I want to make sure the table has a good ground (don't want the ground to be "me").

Thanks for any input....

[shovelon]

In all my years of welding I have never heard of running a separate ground from the table to earth. In some cases you will not use the table, so what's the point?

But then I don't use ground rods either.

[Paul Seaman]

Generally if your working on static sensative things like electronics that is necessary. However the welding circuit is not always ground negative, sometimes it maybe ground posative and not in any way related to an earth ground causing more issues than helping.

I am referring to tig operations and hi-frequency.

I am uncertain what your intent but I think your over thinking the issues.
Peace,
Paul

[Old Sporty]

I've never seen a grounded welding table. Doesn't mean they don't exist, however. Both of my tables sit on wood floors and are not grounded and I've never had a problem. Just have to watch my sparks.

[John at the Waterfalls]

Grounding Equipment and High Frequency interference of computer and stereo.

I am not quit sure why you would want to ground your welding table. Perhaps I missed something in the instructions for my welding equipment.

But ....

The cheap MP3 player I have jacked into the stereo in my shop goes bonkers and reboots when the High Frequency from my TIG machine kicks in. Happens with the Plasma Cutter too.

I have a copper coated ground rod outside the garage by the service panel but have considered driving another one outside adjacent to the wall where my welding table is and then connecting it directly to the 50 amp receptacle that I plug my machines into. I wonder if connecting it to the welding table and the steel cabinet my equipment is in would help limit some of the HF interference.

If this HF hammers my MP3 player, I'm sure the laptop computer is also having to fend the HF off.

There is a difference between an earth ground and the circuit ground clamp on your welding machine. Though at times they might be the same. And then there is the ground in the electrical receptacle which is tied eventually to the earth ground which is also tied to the neutral line in your service panel (Breaker Box). The "ground" that you stand on in your garage is probably not conducting to the earth ground unless it is wet. There is no way to simply and safely explain this in a blog post. I always pull out my book which explains how to wire circuits properly and according to code. So far I am still alive.

Part of the purpose of having a grounding scheme is to keep stray electrons from traveling through you. If you are barefoot in a water puddle or touching your hand on a grounded welding table while holding a broken electrical tool, that is more of a chance for the current to go through you first. So maybe I will just put an extra earth ground to my 50 amp equipment receptacle and forgo earth grounding the table.

I would suggest that you make sure your shop wiring is up to Electrical Code Specifications and that your machines have properly wired receptacles to plug into.

[Broccoli1]

http://www.millerwelds.com/om/o353u_mil.pdf


Check out section 6 for HF Grounding

[Sberry]

Part of the purpose of having a grounding scheme is to keep stray electrons from traveling through you. If you are barefoot in a water puddle or touching your hand on a grounded welding table while holding a broken electrical tool, that is more of a chance for the current to go through you first. So maybe I will just put an extra earth ground to my 50 amp equipment receptacle and forgo earth grounding the table.

An extra "earth" ground is not going to help safety

or touching your hand on a grounded welding table while holding a broken electrical tool,

especially not in this condition, only a wire back to the panel. In a sense anything metal in this shop that one might be able to come in contact with that has the possibility of becoming energized should be electrically grounded. There is some potential for setting up ground loops for welding currents though so unless this is an engineered deal probably not a good idea to ground table, a good thing would be to use GFCI for any power tools though.

[Sandy]

What Miller proposes with their multi-point (mesh) grounding is difficult to maintain, dangerous and a recipe for trouble. In trying to solve a hi-freq problem with the quickest and cheapest method from back in the dark ages they're setting up a scenario where a couple of years down the road you're gonna have ground loops and current flows that'll look like a maze if you mapped them out.

Reminds me of the situation where the lil woman can't navigate in the kitchen with out getting tingled every time she touches the electric stove and the sink or she gets buzzed if she touches the washing machine while the dryer is running, on-and-on. Issues resulting from what Miller is proposing is exactly why the single point grounding system had to be developed.

Sometimes you can cause problems when trying to solve problems if you zoom in too close. Ya need to zoom out and look at the overall picture every now and then.

[Sberry]

My benches have 120V on them. I used gfci on this circuit and did not connect ground wire,,, but,,, they are grounded thru steel in the floor which is electrically grounded at the point I have several welding machines work ground connected. I considered many options,, as Sandy pointed out can get tricky. I have 2 benches, one reason I did it this way was I didn't want cords or wire in 120 circuit to become part of the welding path, say from a grounded drill sitting on bench, etc. My building is steel which added some other issues. Most of this is moot with a single bench that doesn't have its own power though.

[joiseystud]

An extra "earth" ground is not going to help safety especially not in this condition, only a wire back to the panel. In a sense anything metal in this shop that one might be able to come in contact with that has the possibility of becoming energized should be electrically grounded. There is some potential for setting up ground loops for welding currents though so unless this is an engineered deal probably not a good idea to ground table, a good thing would be to use GFCI for any power tools though.

I am not sure why grounding the table would be a bad idea. We weld on steel in buildings while they are connected and they are bonded to the building's grounding system. I think it is a good safety measure to make sure anything metal with the potential to be energized ( a frayed or melted extension cord hot touches the table for instance) is required to have a bond to the electrical panel ground.

[joiseystud]

http://www.millerwelds.com/om/o353u_mil.pdf


Check out section 6 for HF Grounding

I think what they are recommending is not a good idea and may not be code compliant as drawn. Read the emerald book on grounding for some real in depth on grounding, but in general there can be numerous ground rods driven to equalize the ground potential of the earth around the entire building ( we generally drive a ground rod at every perimeter column), but they should all be electrically connected back to the service entrance panel. In the case of a shop where you are looking to ground a number of welding tables, etc and not have a high frequency issue, the best bet would be to install a ground bus on the wall that would tie back to the service entrance ground, then ground the individual items from there. If you are going to drive fifty new ground rods in the area, its ok, but they must electricly tie back to the ground bus or service entrance ground.

[Sberry]

I am not sure why grounding the table would be a bad idea.

I probably didn't word all that as good as it could have been. You are probably right, should be grounded as long as the chassis of the welding machine doesn't sit on this table,,, an example would be if it was and a grounded drill was laying on the table at the same time the ground wires in each could carry welding currents. In my own case as mine are all interconnected and connected to building steel I used gfci (still grounded to electric system just not thru the 120V feed). Only issue with being grounded is if multiple tools from different circuits are on table at same time there would be possibility of ground wire carrying currents,,, again, probably not an issue with stand alone table, just food for thought.

[flukecej]

Multiple Ground Paths BAD IDEA

What Miller proposes with their multi-point (mesh) grounding is difficult to maintain, dangerous and a recipe for trouble. In trying to solve a hi-freq problem with the quickest and cheapest method from back in the dark ages they're setting up a scenario where a couple of years down the road you're gonna have ground loops and current flows that'll look like a maze if you mapped them out.

Reminds me of the situation where the lil woman can't navigate in the kitchen with out getting tingled every time she touches the electric stove and the sink or she gets buzzed if she touches the washing machine while the dryer is running, on-and-on. Issues resulting from what Miller is proposing is exactly why the single point grounding system had to be developed.

Sometimes you can cause problems when trying to solve problems if you zoom in too close. Ya need to zoom out and look at the overall picture every now and then.

Millers Multiple Ground Paths CREATE HF INTERFERENCE, it does not reduce it.

Case in Point, Hypertherm says not to use multiple grounding points. Grounding should be done PER NEC back to Service Neutral. HF interference can also be caused by parallel wire paths to close together, this includes wiring to the plasma cutter, lighting, tools in shop, phones and intercom systems. I have experience with this. I have to unplug the intercom between the house and shop because of HF starter in Plasma Cutter. Also, the shop lighting would wig out because of line feeding plug to plasma cutter was spaced to close in parallel to conduit feeding wall plugs and lights. Increased my parallel spacing and corrected the issue.

Another Case in Point, Franklin Electric Constant Pressure Water Pump Systems can produce HF interference if parallel wire path spacing is not maintained. Also, multiple ground paths can cause electrical interference with touch control lighting, TV's, radios and computers. PER NEC, single point ground to service neutral is recommended to avoid HF and Electrical Interference.

Miller's illastration would actually cause Spurious Emmisions and cause radio and tv interfernce that could result in a visit from the FCC and result in fines and jail time, depending on the scope of the emissions and signals interferred with. Anyone who is a Ham Radio Operator knows what I am talking about. Recently, a local power company was paid a visit by the FCC after power lines owned by the city owned utility was causing Spurious Emmisions on radio bands used by Hams and State Law Enforcement. The problem was poor insulators resulting in multiple ground paths creating RF emmissions that spiked in the HF radio frequency bands.

The idea of grounding a welding table back to earth ground or even the service neutral is suspect. Also, it would lead to stray DC current and voltage that can damage the underground lines and submersible pump installations. I have actually seen this, can cause major issues with water lines (steel or copper) around ones property. Gas companies run powered anti-corrsion systems on their high pressure steel lines. They have to watch the systems closely due to stray DC and AC current causing issues with lines on private property and electrollisys to pipe in water wells. My dad has work records where a natural gas company had to pay for repairs to an irrigation well because of damage to the well casing and column pipe from stray DC current from gas line anti-corrosion protection system.

Also, most underground waterlines these days are plastic, not steel or copper. Plus, anyone who has used steel and copper knows it needs to be coated or wrapped to prevent corrosion of the pipe buried in the ground, thus making it useless as a grounding point. Again, this is why the NEC has everything grounded back to the service neutral.

My welding table is not grounded. I have multiple grinders laying on the table all the time when I'm welding and never had issues tripping a breaker or getting shocked. Now, I have gotten shocked while welding on a steel irrigation stand pipe (buried in ground) and my knee was in damp grass while I was welding, my glove was damp too. The tingle sure got my attention. That is why you should keep your self and welding gloves dry when welding. You do not want to bacome the alternate ground path for your welder.

[cybordolphin]

"you do not want to become the alternate ground path for your welder". Exactly.

If you include your table in your weld circuit... attach what so many erroneosly refer to as the "ground cable" from their welder (it is not a ground cable.... but rather just completes the weld circuit). The table should be grounded. If your cable you have clamped to your table should fail or come apart from the table and you are touching your work piece.... you are at risk of completing your weld circuit (getting zapped).

Good rubber soled boots/shoes and dry gloves/environment lesson that risk. Also as mentioned being on a non conductive board or base, also offers some protection. But does not really eliminate the risk.

I will probably drive a ground rod and run a ground to the table. In the winter here, the lower level garage (where I will be working), can get quite wet/damp and is not the ideal environment for welding (unfortunately it is where I have to work).

The weld table is portable in that it has wheels that do not conduct electricity (table is never grounded), otherwise the legs sitting on the ground might offer some protection.

[kandrwelding]

Rent a hammer drill?

Like most others im not shure why you would dothis but if I was going to do it I would rent a hammer drill from Home Depot and drill threw the floor to ground the table.