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#150099 - 09/24/04 09:11 AM Electrical Hazards and Welding
Webmaster Offline

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Member

Registered: 10/07/00
Posts: 3142
Loc: NY, USA
 Quote:
Introduction

Shock to a welder might be assumed to be an acceptable practice due to the frequency of shocks to welders caused by improper personal protection and awareness. This belief can and has been a fatal assumption.

Many welders have suffered shocks and have only experienced an unpleasant tingle, but muscle spasms from even a mild shock may lead to a fall from a height or cause heart problems which are not readily noticeable or in certain circumstances cause death by electrocution.

The main causes for death or serious injury while welding are as follows: :

1. Poorly maintained or badly connected equipment

2. Shock, from both the welding machine incoming power and the welding voltages.

3. Burn, from flash at the welding machine incoming power cable & connections.


When performing manual arc welding there is a significant potential for the welder to receive a shock by simultaneously touching the electrode and workpiece. This is due to the fact the electrode is changed while the electrode holder is electrically live. Fuses or earth leakage contact breakers do not protect the welder from such a hazard. The potential for electrical shock increases with high-frequency welding

Shock can be avoided by using proper welding techniques and PPE. Training welders in the electrical hazards of welding and electric welding machines is a requirement of OSHA 1910. Training will greatly reduce the myth that being shocked is an acceptable practice and it will prevent injury or death.

2.0 Factors Which Affect The Risk And Severity Of The Shock

2.1 Set voltage (OCV) of the welding machine;

2.2 Use of alternating or direct current (a.c. is 2 to 3 times more dangerous than d.c.)

2.3 Moisture from rain, perspiration or other source;

2.4 How well the welder is insulated from the electrode and the workpiece;

2.5 Which parts of the body are in contact with the work and the electrode. Current flow between the left hand and the torso is the most dangerous;

2.6 Whether the welder has to work in physical contact with the workpiece, particularly in a cramped (kneeling, sitting or lying) position such as inside vessels, pipes and structural components. The electrically hazardous environment does not need to be a confined space.

3.0 Work Methods To Reduce The Risk Of Shock

3.1 When a workplace hazard assessment is conducted, ensure the risk of such electric shock is considered and appropriate measures are taken to minimise the risk (see below).

3.2 The use of dry, hole free welding gloves on both hands while welding, particularly when changing electrodes should be compulsory and be a written safety policy.

3.3 Remove stub ends immediately after welding; do not leave an electrode holder with a stub end in it.

3.4 Turn off the power at end of each shift or when taking a break. Do not drag live leads to the work.

3.5 Leather covered cushions, leather aprons, leather jackets, heat resisting blankets should be used to cover those parts of the workpiece which the welder may contact.

3.6 In hot conditions the risk of electrocution is increased because of clothing and equipment being soaked in perspiration. The risk is far worse in closed environments, such as tanks or vessels. Take frequent rest periods, during which time dry off equipment and clothing. Frequently change or alternate gloves and protective clothing to avoid perspiration accumulating. Ventilate or if possible air-condition the work air. Ventilation will help dry perspiration and cool the body. Cool the face with an air mask. If clothing (including gloves) becomes soaked with perspiration, it must be changed.

3.7 If it is not possible to keep it dry, the environment must be considered extremely dangerous. Either a voltage limited welding power source should be used, or the power should be controlled by a contactor switch on the torch.

4.0 Equipment Checks to Avoid Shock

4.1 Never attempt disconnecting of power receptacle when the main disconnect switch is on (energized).

4.2 Inspect the welding leads a prior to use to ensure that the insulation is not damaged and that the conductor is not exposed.

4.3 Ensure the welding leads are connected to the welding machine by a male plug and that the female portion of the connector is the energized part of the set.

4.4 Ensure the welding lead connection points on the welding machine are shielded to avoid accidental contact with exposed terminals.

4.5 Turn off welding machine in some cases until the welder is in position to make a weld.( In cases where the welder must lie/lean on a grounded surface to perform a welding task the machine should be started by another person when the welder is ready to strike an arc and begin the task.)

4.6 Eliminate the possibility of partially exposing a connection while pulling the leads, male and female connectors of welding leads may need to be taped or otherwise restrained form separating. Welding leads should not be tied in a knot.

4.7 Inspect rod holders for cracked or broken insulated covers, discard or repair insulation if found defective.

Tony Moscioni
Electrical Inspector
Electrical Safety Authority
416.991.4145
Download >> Electrical Hazards and Welding

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Arc Flash PPE Clothing, LOTO & Insulated Tools
#150100 - 09/25/04 09:51 AM Re: Electrical Hazards and Welding
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
 
Tony and Webmaster Bill — That is a good article.

Many of us may not routinely do electric-arc welding, but may be called on to service related equipment and need to understand the hazards present being in close proximity to weldors and welding gear.

One comment on the posted text is that shielded-metal/arc “stick” and tungsten/inert-gas “tig or heliarc” welding use a constant-current power source whose voltage is not intended to be directly adjustable—and may have 80 volts open-circuit regardless of current adjustment—though somewhat less when an arc is established.

For a long time, if welder (machine) open-circuit voltage bothered you, you were considered a lightweight or not a real weldor (person). But, in a hot environment with normal worker perspiration, it is routine to see several pairs of a weldor’s gloves sitting in the sun drying out, that the weldor exchanged wearing though his shift to limit electric-shock “nuisance” or ”discomfort.”




[This message has been edited by Bjarney (edited 09-25-2004).]

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#150101 - 09/26/04 08:24 AM Re: Electrical Hazards and Welding
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Bjarney,
 Quote:
Tony and Webmaster Bill — That is a good article.

Yes I whole-heartedly agree and I would like to say thanks to Tony Moscioni for submitting it.

Having had many years of welding experience myself, I can see what this article is all about.
I've even had the odd tingle from weldors before today, but I've always stopped welding to find out why this is occuring.
One aspect of welders, that I find alarming, is the condition that you sometimes find the Mains voltage lead to the welder in, some that I've seen should have been thrown away years ago!.
For people that repair/service welders, a thorough inspection of all of the leads (High and Low Voltage cables) should be done.
I'd also venture to test the LV leads with a Low Ohms meter from the welder end to the Earth Clamp or Handpiece, you'd be suprised at how poor the connection can be on these leads.
Any Weldor, should have, as a part of their basic training, a thorough knowledge of Electrical and safety principles.
To recieve a shock from a welder and not know why you got it, can only lead to worse accidents in the future.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#150102 - 09/26/04 11:56 AM Re: Electrical Hazards and Welding
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
 
For ‘qualified’ and ‘unqualified’ workers, US OSHA is very clear on what they expect for baseline electrical training in places of employment. [It’s not Rocket Science.]

1910.331 - Scope www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9908
1910.332 - Training www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9909
1910.333 - Selection and use of work practices www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9910
1910.334 - Use of equipment. www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9911
1910.335 - Safeguards for personnel protection. www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9912

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