Thread: How to ground your welder?

2 bob from another bloke who knows a bit about electrons....

Don't try using 6000volts to weld with.

mmmmmm soooooooo now what with the wang dang doodle of a mig welder Ive got hidden in the unpowered shed am I in the nooah or what? I simply run an extention lead the 50mtrs to the shed plug in and away I go.

I was taught stick welding very basically by an old farmer fella up north and was told that as long as the clamp thing has a good clean clamp it would be right? so this is wrong?

Originally Posted by BobL

People think they are invincible in rubber boots and they generally do not make up for other problems.

Hi Bob
You are quite right.Passage of current across the body and through the heart is not a good thing.

I certainly hope readers do not think I am implying that rubber boots alone are the answer.They were but one of a number of precautions listed.

As someone who supervises students ,I take the attitude that all have the potential to be electrocuted and accordingly instruct them in all precautions as outlined in my posts.

I trust people take on board, all of what is written and apply it their situations.Being an instructor I get the feedback on those types situations from my students, in and out of the training workshops where my students had received a boot.Where it occurred I house (at TAFE ) I always investigated.

In twenty years I was only ever involved in one serious hit where a student from another class was hit.He was dripping wet from perspiration from playing footy at lunchtime in the stifling NT humidity.

Apparently he leaned against the steel bench and struck the electrode which stuck to the bench. He then reefed ithe rod loose and it unstuck and him dead center in the forehead. Not only did the current travel through his torso but through his head.
His symptoms were eyes like pinpoints and his skin the colour of cement. Fortunately after a night in hospital he suffered no ill effects.


I believe the regimen of asking students to physically check the quality of the earthing -checking the tightness of the terminal connections before switch on - prevented many problems. Because of the nature of the work, cabling connections become loose on those machines with removable connections.

This was only one of a number of precautions taught.
As an aside Bob ,we discourage our metal tradesmen form wearing rings for a very different reason. Catch a ring on a heavy sheet and it can strip the meat clean off the bone.


Work safe
Grahame

Good post Grahame!

Originally Posted by Grahame Collins

In twenty years I was only ever involved in one serious hit where a student from another class was hit.He was dripping wet from perspiration from playing footy at lunchtime in the stifling NT humidity.

Apparently he leaned against the steel bench and struck the electrode which stuck to the bench. He then reefed ithe rod loose and it unstuck and him dead center in the forehead. Not only did the current travel through his torso but through his head.
His symptoms were eyes like pinpoints and his skin the colour of cement. Fortunately after a night in hospital he suffered no ill effects.

- I can just imagine this happening!

Originally Posted by Grahame Collins

As an aside Bob ,we discourage our metal tradesmen form wearing rings for a very different reason. Catch a ring on a heavy sheet and it can strip the meat clean off the bone.

Reminds me of when my brother fell off a horse and the stirrup buckle caught on his wedding ring and the ring cut his finger clean off - they never found his finger!

Talking about connections - I looked claosely at my cheapie welder last and noticed how sloppy everything looked so I've replaced the cheap cables, connectors and the handpiece, which was cracked and starting to fall apart from falling on the floor a couple of times. I really like the feel of the new stuff - it's all a lot heavier and hopefully should reduce the shake problem.

Originally Posted by Wild Dingo

mmmmmm soooooooo now what with the wang dang doodle of a mig welder Ive got hidden in the unpowered shed am I in the nooah or what? I simply run an extention lead the 50mtrs to the shed plug in and away I go.

I was taught stick welding very basically by an old farmer fella up north and was told that as long as the clamp thing has a good clean clamp it would be right? so this is wrong?

50 mtrs - wow that is a long way - I'd be seriously grounding my work and workbench at that distance.

Originally Posted by BobL

"According to 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 ground, such as a metal building frame. The ground connection should be independent or separate from the welding circuit connection."

I would just like to point out that even though "earthing" (not "grounding") your work table may be a good idea, the standard mentioned (ANSI Z49.1) is an American standard & refers to the American electrical code (NEC). The American electrical system is vastly different to that of the Australian system. Unless Australia has decided to adopt this standard for "Normative" use, it does not apply.

Also, "earthing" is not a simple subject. In fact, it can be very dangerous if not done correctly. Multiple earths used in the MEN system, must conform to the Australian standard of wiring rules (ASNZS 3000:2000). The placement of anything other than an appropriate earthing electrode, can be very dangerous. The use of steel fence posts as temporary earthing electrodes is not safe. Infrequently "watering" a ferrous earthing electrode may speed up the oxidisation process of the electrode (rust) & therefore make it useless & even dangerous, particularly if salt water is used.

Not all electric arc welders are the same. Depending upon their individual design, earthing may or may not be required. Eg if the unit is Class 2 (double insulated), no earthing is required. If the unit is enclosed in metal, the supply cable should earth the unit chassis to the main earth via the distribution board.

If "work tables" are earthed, it should either be done by;

1] a connection to the existing installation main earthing system at the distribution board, or;
2] an extra earth electrode that is connected & tested in accordance with ASNZS 3000:2000.


The 1999 edition of ANSI Z49.1 can be downloaded from;

http://www.aws.org/technical/facts/Z49.1-1999-all.pdf

This is all very interesting but not being an electrician I don't think that I shall ever touch a welder again after reading all the above. That is unless someone can explain in simple terms (I do simple very well) Why I shouldn't just earth my workpiece to the welder and using common sense safety procedures just merrily deposit gobs of metal on the parts I am trying to join.

Do I run a second earth from my bench/workpiece to the earth on my power supply?

Originally Posted by dennford

This is all very interesting but not being an electrician I don't think that I shall ever touch a welder again after reading all the above. That is unless someone can explain in simple terms (I do simple very well) Why I shouldn't just earth my workpiece to the welder and using common sense safety procedures just merrily deposit gobs of metal on the parts I am trying to join.

Do I run a second earth from my bench/workpiece to the earth on my power supply?

If your shed electricals have been installed by a licenced electrician then there is no need to really do anything other than continue to use common sense. Any risk you run is a lot less than other daily stuff like driving your car.

"Do I run a second earth from my bench/workpiece to the earth on my power supply?" I would not touch existing earth circuits or connections.

Unfortunately I have used the phrase "earthing the bench" in my earlier posts which is confusing because some members are taking this to be what you said. I will henceforth call "earthing" to mean, "connected to the household/shed electrical circuit earth" and "grounding" as being directly electrically connected to physical ground. Grounding your bench provides a measure of safety and avoids the ground loops being discussed.

If your shed is more than ~30 m from your house your electrician should have thought about adding a small breaker box and possibly a new earth circuit stake near the shed. Grounding the bench in this situation is still an independent proposition that does not involve the electrical circuit earth.

BTW If you have a metal bench and you test the continuity between your bench and electrical circuit earth and you get an open circuit this is no guarantee that your bench is not at least partially earthed. A conventional multimeter cannot perform a proper AC electical continuity test - this requires a special ~$500 AC continuity meter. A partially earthed/grounded bench is in principle more dangerous (still safer than driving your car) than a fully grounded bench.

Now just to confuse matters, what about if you are using a generator to power a welder?

Well, what if you are using a genny to power your welder, or you're welding in a remote location with a weldanpower unit. For that matter, when I'm using a generator for power and I plug a non double insulated tool into it is there anything I should be doing? (besides using a RCD board)

Mick

Originally Posted by BobL

If your shed electricals have been installed by a licenced electrician then there is no need to really do anything other than continue to use common sense. Any risk you run is a lot less than other daily stuff like driving your car.

"Do I run a second earth from my bench/workpiece to the earth on my power supply?" I would not touch existing earth circuits or connections.

Unfortunately I have used the phrase "earthing the bench" in my earlier posts which is confusing because some members are taking this to be what you said. I will henceforth call "earthing" to mean, "connected to the household/shed electrical circuit earth" and "grounding" as being directly electrically connected to physical ground. Grounding your bench provides a measure of safety and avoids the ground loops being discussed.

If your shed is more than ~30 m from your house your electrician should have thought about adding a small breaker box and possibly a new earth circuit stake near the shed. Grounding the bench in this situation is still an independent proposition that does not involve the electrical circuit earth.

BTW If you have a metal bench and you test the continuity between your bench and electrical circuit earth and you get an open circuit this is no guarantee that your bench is not at least partially earthed. A conventional multimeter cannot perform a proper AC electical continuity test - this requires a special ~$500 AC continuity meter. A partially earthed/grounded bench is in principle more dangerous (still safer than driving your car) than a fully grounded bench.

Now just to confuse matters, what about if you are using a generator to power a welder?

The earthing of metallic work benches is considered to be a part of Equipotential Bonding, which is supplementary to the Protective Earthing system. Australian Standards say that the "Bonding of extraneous conductive parts and their connection to the earthing system may be used to reduce the fault-loop impedance in order to ensure that the disconnection time of the protective device is sufficient..."

Please note the words "bond" & "earthing system". This means that if you wish to earth your metal work bench, it must me done with the use of a cable that is connected to the Main Earth bar in the distribution board. Using an extra earth rod (electrode) will not fulfil this requirement unless it can be proven (by testing) that the complete Earth Fault Loop impedance from the work bench & back to the Main Earth electrode is such that it will not impede the operation of any protective devices (fuses, RCD's & circuit breakers).

In general, Equipotential Bonding arrangements are intended to minimize the risk associated with the occurrence of voltage differences between exposed conductive parts of electrical equipment and extraneous conductive parts.

Your welding unit should already be earthed via its' supply lead.

Originally Posted by journeyman Mick

Well, what if you are using a genny to power your welder, or you're welding in a remote location with a weldanpower unit. For that matter, when I'm using a generator for power and I plug a non double insulated tool into it is there anything I should be doing? (besides using a RCD board)

Mick

A good question Mick.

As per Australian Standards, a portable generator that is in no way connected to your domestic electrical system is deemed as being "electrically separated" & as such, does not require any "extra" earthing.

"Protection by electrical separation is intended, in an individual circuit, to prevent shock current through contact with exposed conductive parts which might be energized by a fault in the basic insulation of that circuit."
The above paragraph basically says that the electrically separate device does not utilise an "earth return" path & therefore, an earth is redundant (or dangerous). The M.E.N. system does use an earth return & so earthing is critical with it.

Further;
"The source supplying a separated circuit shall be —
(a) an isolating transformer complying with AS/NZS 3108; or
(b) a source of current, e.g. a motor-generator set or uninterruptible power supply, that is selected and installed so that the output is separated from the input by double insulation or equivalent."

Also;
"Where a separated circuit supplies a single item of electrical equipment, any exposed conductive parts of the electrical equipment shall not be connected to the exposed conductive parts of any other circuit, including other separated circuits."


In a nutshell, do not provide any "extra" earthing for any part of your generator. You must, however, use an appropriate RCD.

"Ensure that all portable generators comply with AS 2790, 1989 as amended Electricity Generating Sets - Transportable (up to 25 KW). Ensure that the power supply for all construction wiring emanating from a portable generating set complies with this Code of Practice including protection by a core balance earth leakage device with a rated tripping current not exceeding 30mA." (Workcover - Codes of Practice - Electrical Practices for Construction Work).

Originally Posted by elkangorito

"Bonding of extraneous conductive parts and their connection to the earthing system may be used to reduce the fault-loop impedance in order to ensure that the disconnection time of the protective device is sufficient..."

Please note the words "bond" & "earthing system". This means that if you wish to earth your metal work bench, it must me done with the use of a cable that is connected to the Main Earth bar in the distribution board. Using an extra earth rod (electrode) will not fulfil this requirement unless it can be proven (by testing) that the complete Earth Fault Loop impedance from the work bench & back to the Main Earth electrode is such that it will not impede the operation of any protective devices (fuses, RCD's & circuit breakers).

In general, Equipotential Bonding arrangements are intended to minimize the risk associated with the occurrence of voltage differences between exposed conductive parts of electrical equipment and extraneous conductive parts.

Your welding unit should already be earthed via its' supply lead.

I realise that I am not the only one on this thread but please my request for simple was a little tongue in cheek and although I know that a thorough understanding of any subject does require some technical jargon, surely to qualify this with a simplistc explanation would help myself and others to understand. After all I would presume that anyone who can understand what you're talking about with all those long and unfamilliar words would not need preaching to - it's us simple folk that need the preaching, but what is the use of preaching if we can't understand your language?

Denn (once again confused)

Originally Posted by dennford

I realise that I am not the only one on this thread but please my request for simple was a little tongue in cheek and although I know that a thorough understanding of any subject does require some technical jargon, surely to qualify this with a simplistc explanation would help myself and others to understand. After all I would presume that anyone who can understand what you're talking about with all those long and unfamilliar words would not need preaching to - it's us simple folk that need the preaching, but what is the use of preaching if we can't understand your language?

Denn (once again confused)

Denn, sorry if it was a bit "long winded".

Simply put, you can't use American standards in Australia (ANSI whatever) unless that standard has been selected for use by the Australian authorities.
You can earth your "metal welding work bench" in the following ways;

1] connect the work bench to the Main Earth Bar in your Distribution Board (breaker box) with a single insulated copper earth wire (green/yellow). The minimum size of this cable should be about 4 square millimetres. This is the preferred method.

2] with a copper cable of the same size & type as in 1] above, connect the work bench to a separate earth electrode (earth rod in the ground). If this method is used, it must be tested to ensure that it is ok. This method is not preferred.


Both of the above methods must be done by a licenced electrician.

That is exactly what I needed to know. So by connecting to that earth bar any short should return to that earth ( is that right?). The way I see things at the moment is that in the first instance I have an earth on my welder, but should that fail for some reason then I have a backup earth going to my breaker box?

Denn

Originally Posted by dennford

That is exactly what I needed to know. So by connecting to that earth bar any short should return to that earth ( is that right?). The way I see things at the moment is that in the first instance I have an earth on my welder, but should that fail for some reason then I have a backup earth going to my breaker box?

Denn

This is not quite correct.

The earth that you put onto the work bench is purely an "equipotentential" earth. It can assist in helping circuit breakers to trip under a fault condition but it is not a Protective Earth. This means, you still must ensure that the earth in your welding units supply lead (a Protective earth) is intact & functional. It does not mean that you can get lazy about "earthing" (no offense intended).

Since we are talking about electricity & workshops, I am of the opinion that it would be a very good idea to ensure that all metallic workshop/shed fixtures (stationary) are equipotentially bonded. This also includes the physical structure of the workshop/shed if it is metallic. That is, an electrician can run earth cables to each of these fixtures & ensure that they are appropriately connected to the main earthing system. This will not require the installation of extra earth electrodes (rods in the ground).

Originally Posted by elkangorito

. . . . . .with a copper cable of the same size & type as in 1] above, connect the work bench to a separate earth electrode (earth rod in the ground). If this method is used, it must be tested to ensure that it is ok. This method is not preferred.

Both of the above methods must be done by a licenced electrician.

The loophole word his is "can", ie "You can earth your "metal welding work bench" in the following ways;"

Since it does not say you "must", and since a bench is not an electrical appliance, there is no law preventing anyone from running a cable between a work bench and a steel pipe driven into the ground. You also do not get it tested unless you are claiming it to be an earth. "Your Honour - it's an alternative to me wearing me foilie while I'm welding". It's cheap and simple to do and if I was welding every day I'd be doing it to my bench.

The legalities start when you start fiddling with the electrical appliances and their circuit.