Canada’s Position on Welding Power Source No-Load Voltage

Do No Harm: Canada’s Position on Welding Power Source No-Load Voltage

In 2019, the CSA Group published the Canadian National Standard CSA W117.2:19 Safety in welding, cutting, and allied processes. For environments in which there is an increased risk of electric shock, the Standard includes a requirement that a voltage reduction device—that limits the open circuit voltage of MMAW, GTAW and Air Arc Gouging power sources to 12 volts—is used. Dave Hisey, Chair of the Canadian Safety in Welding Cutting and Allied Processes Committee, provides an overview of the Standard.

Background: Case Studies On 25 June 2014, a 29-year-old male welder died when the welding electrode penetrated his neck. He was seated on the building structure to which his return lead was connected. This was the case which caused the reduction in acceptable no-load voltage (open circuit voltage or OCV) under specified conditions to 12 volts within Canada.

From Engineering Report, Electrocution Incident Carmuse Lime, Dundas Operations, Dundas, Ontario, Canada (Cement Plant Kiln): • The kiln was in operation and extremely hot humid (50°C and 85% humidity) and noisy at the time of the accident. • The welding spot was tight, awkward, and the lighting was poor. • There was no insulating material to isolate the welder from the work piece (coal bin) or other metallic parts inherently connected to the work piece. • There was no safe place to place or store the live electrode holder • The return lead was connected to structural members more than 30m from the area where the victim was welding creating stray welding currents throughout the structure.

Does any of the above sound familiar to repair and maintenance welders?

Electrical Contact Points The coroner detected only one massive entry wound, where the electrode penetrated the victims neck. The electrode had embedded in the victim’s neck at a downward angle, exit burns were found in the vicinity of his knee.

In the follow-up court review of the death, there was discussion that the victim may have committed suicide as the investigators had no experience with electrode shock fatalities, and for part of the actual investigation could not believe that a welding machine could kill anyone. For the family, I reviewed and created a report on 18 welding electrode fatalities I had on file.

In a review of 18 individual cases of electrode shock death, I found that: • 8 had electrode contact points of face or neck • 2 cases rescuers were unable to remove the electrode from the victim’s mouth due to locked condition • 11 were found in lying position in contact with metal or ground • 1 sitting position on base metal • 1 foaming at the mouth • 1 had high enzymes (muscle damage or excessive use) • 1 had lung and kidneys congested with fluids.

Additionally, one of the serious injury cases had direct forehead contact with a new electrode, welder lying in prone position - knocked unconscious for an undetermined time period.

Face and neck contact is a normal finding in fatal or serious injury welding electrode shock occurrences.

From a welding electrode fatality perspective, the 25 June 2014 investigation provides a disorganised report; concentrating more on the primary power circuit than the welding circuit which was the cause of the fatality. This is not unusual; I have looked at many welding electrode fatalities where the investigation team is not familiar with this cause of death. They eventually get to the cause.

The Welding Current Electric Shock Injury or Fatality Report The Report was created to simplify investigation in cases of welding electrode shock injury or fatality. This report was published as Weld Australia‘s Technical Guidance Note TGN-SW03 Welding Electrical Safety—Electric shock injury and electrocution reporting. It is available and can be downloaded free of charge, for your use via the Resource Centre on the Weld Australia website. Please use this form as we learn much from welding electrode injuries when welders are alive to explain what happened, or, nearly happened.

It was the fatal accident of 25 June 2014 and the investigation into it which caused the Canadian CSA W117.2 technical committee to create the changes to CSA W117.2 Safety in welding cutting and allied processes.

This individual had also suffered such a severe welding electrode shock one week before that he went home early from work physically sick. Had the Welding Current Electric Shock Injury or Fatality Report been available and used to understand the issues which allowed him to receive such a severe shock; one more young welder, husband and father, son and brother may still be alive today.

My friend Darren and I had an email discussion on the voltage levels specified in IEC 60974-1 prior to submitting our national vote on that edition of the standard in a January 2016 email.

Darren’s response to my question on how our vote should go: “In regard to voltage level [specified in IEC 60974-1], I have always advocated a much lower level being acceptable. Because I have the knowledge that our test work revealed worst case scenarios of body resistances being less than 100 ohms, in good conscience I cannot endorse having open circuit voltage higher than 12VDC. This voltage level is achievable with no effect to the welding process, so to recommend a higher level, would on my part, be negligence.”

Darren Green died of a heart attack on 3 November 2020 at the age of 58. Although a few years younger than me, Darren had been my mentor on this subject from the early 1990s when I first began working on finding ways to reduce the incidents of welding electrode shock and the injuries and fatalities eventually caused. His work continues through CSA W117.2 technical committee and the lessons he taught us.

CSA W117.2-19 Clause 7.2.1.2.21

Accordingly, for high risk welding environments, CSA W117.2 specifies: device that allows 12 volts or less, no load voltage shall be used where all the following conditions are met: a) in environments with increased risk of electric shock (see Clause 3); b) when the welders body is likely to be in contact with the metal being welded or with the earth; c) when using the following welding or cutting processes: SMAW, GTAW, or CAC/CAG; and d) when the welding or cutting machine or system is not equipped with a circuit that de-energises the welding machine secondary voltage until the welder is safely positioned, the electrode is installed in the holder/torch and is ready to strike the arc with a normally open manual electrical switch.

Further:

CSA W117.2-19 Clause 7.2.1.2.31

To reduce the hazard to life, a voltage reducing device that allows less than 12 volt no load voltage should be used where all the following conditions are met: a) in environments with increased risk of electric shock (See Clause 3); b) when the welders body is likely to be in contact with the metal being welded or with the earth; and, c) when the welding orcutting machine or system is not equipped with a circuit that de-energises the welding machine secondary voltage until the welder is safely positioned, the electrode is installed in the holder/torch/gun and is ready to strike the arc with a normally open manual electrical switch.

These requirements are consistent with the recommendations within Weld Australia’s Technical Note 7 Health and safety in welding, Technical Note 22 Welding electrical safety, and Australian industry’s best practice for high risk welding environments.

1 Source: CSA W117.2:19, Safety in welding, cutting, and allied processes. © 2019 Canadian Standards Association. Please visit https://www.csagroup.org/store/

With the permission of Canadian Standards Association, (operating as “(SA Group”), 178 Rexdale Blvd., Toronto, ON, M9W lR3, material is reproduced from CSA Group standard CSA W117.2:19, Safety in welding, cutting, and allied processes. This material is not the complete and official position of CSAGroup on the referenced subject, which is represented solely by the Standard in its entirety. While use of the material has been authorized, CSA Group is not responsible for the manner in which the data is presented, nor for any representations and interpretations. No further reproduction is permitted. For more information or to purchase standard(s) from CSA Group, please visit store.csagroup.org or call 1-800-463-6727.