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  1. #1
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    Default How to ground your welder?

    Gidday

    Making sure your welder is grounded appropriately is essential Heres a good introductory article from the Lincoln Website:

    http://www.lincolnelectric.com/knowl...ing_safety.asp

    Wanted to bring this one up as an issue particularly in the age of highly portable inverter units!

    It's really worthwhile considering issues like:

    How do i ground my welding table?

    Whats the best way to ground my inverter (Is this necessary?)

    What do I need to consider when looking at grounding my 'Rig'?

    .................Hopefully Grahame will give us a few more pointers on this one!

    REgards Lou
    Just Do The Best You Can With What You HAve At The Time

  2. #2
    BobL is offline Member: Blue and white apron brigade
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    A key paragraph on that web page.

    "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."

    At work we have a grounded table and the way to check that your piece(s) are grounded is to connect the welder clamp to the table rather than the piece and clamp the pieces to the table or a vice mounted in the table. Then if you can strike an arc on the piece the pieces should be grounded. Must make myself a ground for home some time. I saw the sparky used a star picket driven about 4ft into the ground for our extension. Might do the same for the shed - has anyone else done this?

  3. #3
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    Default

    Quote Originally Posted by BobL View Post
    Might do the same for the shed - has anyone else done this?
    Crikey, I better look into this. At the moment I just use a stainless bench on a steel frame that sits on the dirt. Is that a good enough ground?
    I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones.
    Albert Einstein

  4. #4
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by martrix View Post
    Crikey, I better look into this. At the moment I just use a stainless bench on a steel frame that sits on the dirt. Is that a good enough ground?
    Err . . . no, especially if the dirt is dry.

    A welder is an "usual tool" in that it has a conductive path direct into the guts of the machine. The grounding of a bench is a safety precaution against something going wrong inside the welder and the 240V somehow connects itself to clamp line. When you thus pick up the clamp and get zapped. It would be nice to ground the rod holder as well but then the welder wouldn't work. Most people will not bother with doing this and live very successfully. Also it is not always possible to do when working on vehicles or buildings etc However, seeing as it takes very little effort to do for a stationary bench it is probably worth doing.

  5. #5
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    Quote Originally Posted by BobL View Post
    I saw the sparky used a star picket driven about 4ft into the ground for our extension. Might do the same for the shed - has anyone else done this?
    I wouldn't. Star pickets are not the best way to earth anything ... I would go to the local electrical supplier and get an 1800mm copper clad earth rod and clamp (and wire if you need it). Also I think your shed (if it's steel) should already be earthed (i.e. connected to the electrical earth and therefore an earth rod) so you might just be able to connect the bench to the steel structure of the shed.
    Cheers.

    Vernon.
    __________________________________________________
    Bite off more than you can chew and then chew like crazy.

  6. #6
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    Default

    I bet theres a rule that says your sparky shouldnt have used a star picket! And him putting in a second one rather than useing the original doesnt sound right either (well not when talking about the one building) Multipul earths will creat a "potential difference" between the earth stakes and thus a voltage difference between the various earths in the building... i guess if they are joined together it may be ok, but i dont think its normal practice...
    It's Ripping Time!!!

  7. #7
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    Default Avoid a boot

    Guys,
    I would be more inclined to direct my efforts in favour of the electrical/mechanical connections of your earth return and electrode cables. For those who have not had a boot off the welder its like touching the spark plug when the mower is going.

    Usually when someone gets a boot it is usually a result of a poor connector somewhere in the secondary cables..The welding current is trying to take a short cut home.

    Because we move our cables around-crikey some even wrap their cables up when finished- the connectors move ever so slighty. Looseness causes a resistance heat build up which makes the problem yet worse again.

    The modern taper twist pins dont suffer this problem.If you have an older bolt up connection system check that on a regular basis.

    Crappy A frame earth clamps that are weak springed because of heat damage, need replacement.They are the cause of more than a few welding problems as the weak connection does not allow full current through the work.
    Wherever you can clamp directly to the work.

    The job if sitting on spatter balls doesn't get full electrical value.

    Twist grip electrode holders made of bakelite type plastic wear and crack so it possible to to get a metal to skin connection there. pull them apart and tighten them up periodically and or replace.

    Check your gloves for cracks and dampness.

    Place an insulator mat on the floor a bit of conveyor belt is good.Did you know dry concrete can conduct enough current to do you a nasty- The Tafe electrician teachers showed me that one.

    Finally it is the micro amps that do the damage.If you have suffered a boot get a check up pronto.it is possible to suffer a heart attack within 24 hrs

    And of course wear your boots_ I said boots not thongs aye!

    Grahame

  8. #8
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Mick C. View Post
    I bet theres a rule that says your sparky shouldnt have used a star picket! And him putting in a second one rather than useing the original doesnt sound right either (well not when talking about the one building) Multipul earths will creat a "potential difference" between the earth stakes and thus a voltage difference between the various earths in the building... i guess if they are joined together it may be ok, but i dont think its normal practice...
    I agree on the two earths and the fact that this can set up ground loops BUT I'm not talking about a second electrical circuit earth but actually earthing a welding table.

    BTW the star picket was also not a second earth but it replaced the old one which was loosely bolted to a sheet metal sewage vent/chimney that had almost rusted through and was in danger of not even being connected to the ground! Someone, a house owner?, had also connected an earth to the copper mains plumbing! Heaven knows when any of this was done as the house is nearly 100 years old. The wiring is our house was a mix of new and old cloth and rubber coated wire. The house had supposedly been rewired before we moved into it in 1978 but every time I went up into the ceiling space I came down with 10's of metre of old cloth and rubber coated wire. In 1994 we had the house completely rewired from scratch and that was when we had the new earth put in.

  9. #9
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Grahame Collins View Post
    Finally it is the micro amps that do the damage.If you have suffered a boot get a check up pronto.it is possible to suffer a heart attack within 24 hrs
    Saw a guy getting a 415V boot a couple of years back. He was thrown to the floor like a wrestling throw - fortunately it flung him clear of the exposed cable and he seemed OK. We tried to get him to go to see a doctor but he refused and being a sort of loud mouth character that never stopped talking after the shock he went silent so we knew he was not OK. After about half an hour or so of his shock he disappeared and we thought he might go home so we called his missus and explained what happened. She hauled him out of bed and down to the hospital. It turned out he had these strange internal burns and eventually vomited blood and he was in hospital for a week and off work for another 2. Not nice.

  10. #10
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    Most industrial generators that we hire for outdoor gigs come with a star picket earth stake. The reason being that copper is just too soft to repeatedly hammer into the ground and get out again. Obviously it is the best choice but a star picket is better than nothing.

    The main thing is that the earth stake is in an area where the soil is moist and this is why the standards say it must be placed in an exposed area. When I water the garden in summer, I also water the earth stake (not expecting it to grow) but to reduce resistance caused by dry soil. In some instances, it is necessary to add salt the the water to ensure that the conductivity is good.

    I remembered when I wired up my workshop, I asked the sparky who came to certify my work and do the final connection to the mains if I should put in an earth stake or not. He said as the workshop is only 30m from the house, it was not necessary. There are some issues regarding multiple earth stakes but I cannot remember if this just relates to MEN bonding (settle down ladies) which is the point at which the neutral and earth are bonded. The MEN (Main Earth Neutral) bond should only be done once as far as I can recall. However, this was a few years back and I cannot remember the full details. Electricity kills (commonly a few days after a jolt), so when in doubt call a local sparky.

  11. #11
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    Default

    Finally it is the micro amps that do the damage.If you have suffered a boot get a check up pronto.it is possible to suffer a heart attack within 24 hrs
    I spent all of last long weekend in hospital after a suspected heart attack.
    I am still getting tests done to find out what's going on, as the Cardiologist cannot explain why such a fine example of a man such as myself is getting the heart pain. I beleive it is probably my very high intake of red wine, and salt to keep my blood pressure up that saved me. My doctor doesn't agree.

    I weld up stuff at least weekly, and am regularly zapped for one reason or another. Usually when I kneel down on one leg to weld up something in a difficult position, and I get zapped through the ground.

    Do you have more info Graham?
    I've been stick welding since I was a kid, and never heard of that, although I am self taught, so haven't done any safety training.

    Thanks.... I don't want to die just yet.

  12. #12
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    Default

    how do you ground half a dozed bricks, placed on a brick floor???

    Well thats what we use as a welding table
    I may not have gone where I intended to go, but I think I have ended up where I needed to be.

    My Other Toys

  13. #13
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    Default

    I remembered when I wired up my workshop, I asked the sparky who came to certify my work and do the final connection to the mains if I should put in an earth stake or not. He said as the workshop is only 30m from the house, it was not necessary.
    He is technically correct however it is often cheaper, and is certainly safer to whack an earth stake in at the base of your sub-board at the workshop end. Often cheaper, beacause you don't have the cost of an extra earth wire back to the house board, which may mean you can use smaller diametre conduit as well if that is what you need. Safer because earthing efficiancy is all about resistance, or more accurately... lack of resistance. The closer the earthing point is to the machines that you are running in the shed, the better chance the operator has of not copping the full whack of current, should there be a fault or accident. Induction motors, lights etc etc, all work perfectly without an earth, but everything in your shop, except double insulated portable devices, should be properly earthed. My brother is a sparky. I always wire up everything, and Gelnn checks it out before service is comissioned. We always check all earths first, measuring impedance (or lack of), and get that side sorted first.

  14. #14
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    Hi Fossil,
    I think the issue of not becoming part of the circuit is of a larger problem that the earth of the table itself.

    An rubber mat and proper safety boots or shoes all play their part in separating you from the current.Same goes for good tight electrical connections. Cabling moves and connections loosen up.
    I see the kids at school get booted and blame the electrical integrity of the machine when it isn't so.

    Leaning on the machine, damp gloves (cos they insist of taking a red hot coupon to the trough and they get wet) all create conditions that can cause the operator some problem.

    Improper mechanical/electrical connections in the earth clamp to cable or cable to terminal.
    If the earth connection is not allowed to earth it wants to take a short cut -THROUGH YOUR BODY.

    Minimize the possibilities of bad earthing by:

    • Rubber or cork insulation mats
    • Good footwear.
    • Good cabling connections


    Grahame

  15. #15
    BobL is offline Member: Blue and white apron brigade
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    Default

    Grahame, I don't know a lot about welding but I know a shirt load about electricity. Relying on rubber mats and boots alone to not get a boot is not good OHS policy and often physically makes no sense either.

    Touching a live circuit with one hand while holding onto anything that's even 1% earthed with the other hand means the electrickery is gonna pass that way (ie right across your heart) and no amount of rubber matts or boots will help. People think they are invincible in rubber boots and they generally do not make up for other problems.

    I once accidentally stuck my hand inside a bit of electronics gear and had 6000 V hit the tip of my ring finger. The current ran half way down that finger to a point where it was touching a grounded metal cabinet. There was a loud bang, I got thrown half way across the room and my finger turned a green purple over a couple of days. I had rubber soled boots on - didn't help at all. Just as well my finger was also touching the grounded cabinet because my heart was probably next in line.

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