How to Ground Welding Table? What Happens If You Don’t?
If you haven’t been grounding your welding table or workpiece during welding, you have been jeopardizing yourself and your entire welding equipment.
Ground your welding is pretty simple and involves attaching a grounding clamp to your welding table. Not grounding your welding table can cause a stray voltage to arise from your welding work to jump to you or the nearby people and other electrical equipment. High quality welding tables can minimize that but it wont be reduced to zero.
Read the following guide to discover more details on how to correctly ground your welding table and what can happen if you don’t do this important step.
Why does a welding table need to be grounded?
The MAIN reason why you need to ground your welding table is to ensure you create a safe working environment for yourself and all your welding equipment.
Failing to ground your welding table subject you to electrical shocks and even damage your welding machine, the work piece, and other nearby equipment.
As you might already know, welding an arch involves using open electricity circuit to weld. Thus, any stray voltage (which is highly likely to happen) from the welding machine will most likely get conducted into you if your body is on the path of the least electrical resistance.
But don’t get scared yet! The voltage involved in welding is usually low and not likely to electrocute you when you get zapped by a stray voltage from your welder.
However, it’s not 100% safe! The shock can be surprising and painful to you. It can also damage your welding machine, your workpiece, and any nearby gear if you drop the welding torch.
If you’re doing arch welding, a ground clamp is a must-have since the arch from the electrode arises from the TIG torch trying to make a circuit with your welding table.
If you don’t have a work lead (i.e., the grounding lead) in your arch welding setup, the torch won’t arch and you won’t be able to weld.
How do you ground a welding table?
You can ground a welding table of any height by introducing a ground clamp in your welding circuit. Most of the welding tables you order usually come with a ground clamp to make it easy to ground them. If you’re making your own table, make sure you include a clamp for grounding it.
Most welders attach the ground clamp on the table itself while others clamp the workpiece they’re working on. Whatever method you decide to go with, you’ll arrive at the same results—a well-grounded welding table.
Let’s say you choose to attach to the working table. In this case, we suggest that you attach the clamp flash to the underside of your table. This is a nice position to keep it from getting in your way when welding.
However, grounding the workbench itself makes it part of your welder circuit and you’re sure to experience some zapping or ambient shocks whenever you touch the table.
While this isn’t something serious and can’t cause any major hazard, some people still would want to avoid it. And in this situation, the only option is to go for attaching to the workpiece itself. As we have said, this will serve the same purpose of effectively grounding your weld.
If you’re dealing with an irregular workpiece and you can find an ideal place to clamp it with the standard welding clamps, you can simply solve this by attaching the larger vice grip welding clamps to your workpiece first and then clamping them (the vice grips) with the electrical grounding clamp.
Different methods of grounding welding table:
Now, there are a couple of ways you can ground your welding table. We have listed the top methods below to help you choose the one you prefer.
Heavy-gauge wire method
The simplest method of grounding your table involves using a heavy-gauge insulated copper wire (4-gauge wire will do) with the grounding lugs and connecting it to your home ground wire. This is simple but works just fine to give you a grounded welding table.
If you want to, you can opt to run a separate ground wire to earth rod. But if you don’t get access to a regular ground wire, you can follow the established practices and codes for electrical codes to come up with one.
Ground to water pipes
Another way to establish connection between your welding table and the earth is by using metal water pipes. This method of using water pipes as electrodes has been in practice for years and works quite well.
However, NEC (National Electrical Code) has introduced additional requirements for using water pipes as grounding for safety reasons. One such requirement is that you must have at least an additional electrode installed when using a water pipe as the electrode.
Other requirements by NEC include:
We also don’t highly recommend this grounding method due to the issues of corrosion and the fact that the use of plastic fittings can break the grounding path and render this method ineffective for you.
If you have a modern home, chances are high it's grounded to the rebar embedded in the concrete foundation. The contractors usually leave the rebar exposed to the outside and you just clamp a grounding electrode conductor onto this “sticking out” rebar to ground your welding table.
Though featuring less direct contact with soil compared to earth rods, the matrix of these connected rebars offers sufficient metallic mass to meet your grounding needs.
This grounding method has started being affected by rust and corrosion at the points where the grounding connect meets the rebar, leading to a weakened grounding system. For your information, you can read our content on cleaning rust off a welding table.
Nonetheless, if your rebar grounding is still in good condition, you can use it to effectively ground your welding table.
Dedicated earth rod grounding
You can also run a dedicated earth rod for grounding your welding table. However, keep in mind that this method is demanding as you’ll have to pound an earth rod into the dirt and even use power equipment to force an 8ft. metal rod into the ground. That’s going to take time and effort, and it’s absolutely not really worth it unless it is the only option you have.
Doesn’t the welder have a ground clamp already?
Most welders often confuse the earth clamp on their welders as the grounding clamp for their table. But this isn’t the real welding table ground.
This clamp you call grounding clamp is simply a return clamp and its job is to return current to your welder. This is unlike an earth ground which makes an actual physical connection with the ground through a conductive metal.
Earth ground is what your metal table needs to become grounded.
The American National Standards Institute (ANSI) even states in their standard operating procedure Z49.1 “Safety in Welding, Cutting, and Allied Processes” that you must ground your welding table or work piece separately from the welding circuit to help limit its voltage to the ground.
This limiting of voltage to the ground is essential to preventing electrical shocks in case your equipment gets misconnected or the insulation fails.
A freestanding welding table not connected to the earth is NOT considered grounded. It becomes part of your welding circuit. It acts as a huge conducting chunk of metal that serves as an important part of your welding circuit. Placing your metal workpiece on this table or clamping the lead to it simply shows the balance seeking electrons where to go.
If you don’t do anything to the table, your welding circuit will remain isolated from the ground.
Some welders argue that that since the table is connected to the welding machine and the machine is already grounded (via the power plug), so it needs no additional grounding. The truth, however, is this ground is meant for protecting the machine only.
A ground table still requires grounding of its own to the earth. And when you ground it to earth’s rod or a suitable metal structure, it will be grounded on its own and won’t extend the grounding to the welding machine.
Grounding your table is all about providing actual earth grounding to your welding circuit.
Can you weld without grounding your welding table?
One of the most asked questions by welders is where you really need to ground your worktable before welding. The short is YES, you can weld without grounding your table.
Most welders usually weld without first grounding their worktables. They instead opt to attach a workload close to their workpiece to serve as ground lead.
As you can see, this doesn’t mean they entirely weld without grounding their table/work. They simply substitute the whole process of grounding the welding table with something simpler and faster.
Why avoid welding the table instead? You might ask. The main reason most welders avoid grounding their welding tables is that when they do, the electrical resistance is usually created and leads to overheating damage and can sometimes result in a fire hazard depending on the level of voltage you’re using.
Does this mean we encourage you to weld without grounding your welding table?
NO. We always urge you to make the effort of grounding your worktable. If you don’t do it, you risk creating radiofrequency malfunctions to your surrounding electronic equipment. The high-frequency signals will be radiated away from your welding arc and interfere with nearby electrical devices including TV, radios, and so on.
Grounding your welding table also comes with its own risks. Since welding involves a variety of frequencies, voltages, and polarities, connecting all these temporary spikes to the electrical system of your building can result in shortages and other electrical-related issues.
Now that you know why grounding your welding table is important, you should start doing it before any welding takes place. Sometimes you might get lucky if you don’t ground your table as you won’t experience any damage. But it’s not worth risking your safety and that of other equipment in your welding shop.