By Grant Laidlaw
All persons who use electric arc welders should have a working knowledge of the electrical hazards that are an inherent part of their job.
Question 1:
Johann asks: Grant, many refrigeration people work on or near electrical power without any idea to the hazards. I realise that this is the basics, but it should be important. What about electrical safety using arc welders? Any advice?
Hi Johann. Many refrigeration people do work with electricity as it forms part of the required skills set. In the last issue of RACA Journal I looked into general safety. Let us now look into the safety aspects when arc welding.
The people using this equipment need to take steps to eliminate and/or mitigate hazards. The following are some of the safety rules and guidelines that apply to welding:
Electric shock is a hazard associated with both electric resistance and electric arc welding. A shock can occur when the equipment isn’t properly earthed; through direct contact with energised leads or from contact with the welding leads via moist gloves or clothing (including damp floors). Environmental conditions (such as wet or cramped spaces) may increase the likelihood of a shock. Even if the shock itself isn’t too serious, the jolt could cause a possible fall.
A coiled extension lead that has melted. Image credit: ACRA
Always wear dry, hole-free insulating gloves to protect against or reduce electric shock. The welder should also wear rubber-soled shoes, and use an insulating layer, such as a dry board or a rubber mat for protection on surfaces that can conduct electricity.
Earth the piece being welded. The insulation on electrode holders and electrical cables should be kept dry and in good condition. Do not change electrodes with bare hands, wet gloves or when standing on a wet floor.
In arc welding, the open circuit voltage that exists between the electrode holder and negative during the no load period, presents a potential hazard to the person and those around him. The worker becomes exposed to this voltage when setting up work, changing working position, or changing welding electrodes.
The insulation on welding electrode holders is sometimes damaged from rough use and from moving welding equipment through and around tight spaces. Contact with skin or damp clothing by the bare metal exposed when this occurs can result in a shock.
Do not work alone where conditions are especially hazardous, such as where electric shock is a hazard, or where ventilation is poor.
“Electric shock is a hazard associated with both electric resistance and electric arc welding.”
The avoidance of electrical shock is largely within the control of the welder. Therefore, it is especially important that the welder be thoroughly trained on safe welding procedures. Safe procedures must be observed at all times when working with equipment having voltages necessary for arc welding. These voltages can be dangerous to life. Even mild shocks can cause involuntary muscular contractions. Any electric welder, AC or DC, has the power to cause electrocution if the electrode touches your bare skin while you are earthed.
To avoid electric shocks and possible electrocution, personnel should take the following precautions:
- Welders must always be aware about the possibility of electrical shock. Wet working conditions must be avoided because water is an excellent conductor and electricity will always follow the path of least resistance. Even a person’s perspiration can lower the body’s resistance to electrical shock. Standing on a dry rubber mat, or when welding outdoors, standing on a dry board is advisable.
- Poor connections and bare spots on cables further increase the possibility of electrical shock, so equipment operators should routinely inspect for effective earth connections. A proper earth connection is always necessary because it provides a safety connection from a welding machine to the earth.
- Connections typically used for earthing an engine-driven welding machine include a cable connected from an earth stud on the welding machine to an earth connection or a metal stake placed into the ground.
- The workpiece being welded and the frame or chassis of all electrically-powered machines must be connected to a good electrical earth. Chains, wire ropes, cranes hoists or lifts must never be used as earth connections.Work leads are not used as earth leads. A separate lead is required to earth the workpiece or power source.
- Never touch the electrode or any metal object unless the power source is off.
- When installing welding tables, connect the frames of each unit as such to the building earth. Conductors must be adequate to carry ground currents safely. Equipment made electrically hot by stray current may deliver a powerful shock.
- Never earth to an electrical conduit or to a pipe carrying any gas or flammable liquid such as oil or fuel.
- Train personnel using welding and cutting equipment to reduce the risk of injuries, fatalities, and electrical accidents.
- Read all instructions, labels and installation manuals before installing, operating or servicing the equipment.
- Do not strike the arc without covering the face and eyes. Give warning to others before striking the arc.
- Wear dry insulating gloves in good condition and protective clothing.
- Isolate/Insulate yourself from the workpiece and ground by wearing high top rubber soled shoes or standing on a dry insulated mat or platform.
- Use fully-insulated electrode holders. Never dip the holder into water to cool it.
- Do not touch holders connected to two welding machines at the same time.
- Do not allow the holder or electrode to come in contact with any other person.
- Do not use worn, damaged, undersized, or poorly joined cables.
- Make sure all connections are tight.
- Do not wrap cables carrying electric current around your body.
- Do not touch an energised electrode while you are in contact with the work circuit.
- In confined spaces or in locations that are electrically hazardous due to water or perspiration, utilise DC output machines and do not work alone.
- Turn off all equipment when not in use.
- Use only well-maintained equipment. Repair or replace damaged parts before further use.
- Welding can further cause other hazardous conditions such as fires. Always take extra precautions to prevent all accidents while welding. Simple preventive actions such as placing your welding cables and other equipment where they will not obstruct passageways, ladders, and stairways will help prevent accidents.
When it comes to extension cords:
- Never use an extension lead when rolled up and in particular when welding. There will be heat build-up which may result in the extension melting causing unsafe electrical conditions and posing a fire hazard.
- Keep extension cords away from heat, oil, chemicals, sharp edges and ensure they do not become a tripping hazard.
- Make sure the extension cord is for the correct amperage and has the proper plug.
- Don’t overload electrical outlets.
- Never disconnect power by pulling on the cord – disconnect at the plug!
Johann, I hope that this assists you with your electrical safety issues when welding and in general.
Thank you for all your questions. Send your problems (and sometimes your creative solutions) to acra@netactive.co.za with ‘Solutions Page’ in the subject line.
You may include pictures.
References:
