Arc welding equipment requirements

Employers must choose welding equipment that is safe for the specific job and meets the application requirements in paragraph (b). Per 1910.254(a)(1), select apparatus designed for the process, environment, voltage, and duty cycle you will use.

• Check machine ratings and suitability for the work environment under 1910.254(b)(2).
• Use machines built to industry standards referenced in 1910.254(b)(1) (e.g., NEMA EW-1 or ANSI/UL standards) when available.
• For unusual service conditions (corrosive fumes, steam, oil vapor, dust, weather, shipboard), provide specially designed machines as listed in 1910.254(b)(2)(ii).

Arc welding equipment must be installed safely following the installation rules in paragraph (c) and Subpart S electrical requirements. The standard says installation including power supply must comply with 1910.254(c)(1) and the electrical requirements in Subpart S.

• Provide a disconnect or controller at or near each welding machine when not integral, per 1910.254(c)(3)(i).
• Ensure overcurrent protection and supply conductor sizing follow Subpart S and 1910.254(c)(3).
• Ground frames and enclosures as required in 1910.254(c)(2)(i).

Only workers who have been properly instructed and qualified may operate arc welding equipment, as specified in paragraph (d). 1910.254(a)(3) requires employers to provide instruction and qualification for operators.

• Training should cover machine hookup, grounding, safe use of electrode holders and cables, and manufacturer instructions referenced in 1910.254(d).
• Make sure operators know to report defects and to stop using unsafe equipment as described in 1910.254(d)(9)(i).

For manual arc welding, the standard limits open-circuit voltages to 80 volts for alternating current (a.c.) and 100 volts for direct current (d.c.). See 1910.254(b)(3)(i)(A) for a.c. and 1910.254(b)(3)(ii)(A) for d.c.

• Automatic (machine or mechanized) arc welding has separate limits: 100 volts for a.c. automatic per 1910.254(b)(3)(i)(B) and 100 volts for d.c. automatic per 1910.254(b)(3)(ii)(B).

If a process requires open-circuit voltages above the limits, employers must provide means (insulation or other methods) to prevent operators from accidentally contacting the higher voltage. 1910.254(b)(3)(iii) requires adequate insulation or equivalent protection.

• Use insulated electrode holders, guarded terminals, barriers, or remote controls to keep operators from accidental contact.
• Consider automatic no-load voltage reduction controls for wet or warm conditions as recommended in 1910.254(b)(3)(iv).

Terminals for welding leads must be protected so personnel or metal objects cannot accidentally contact live parts, using dead-front receptacles, recessed openings with hinged covers, heavy insulating sleeving, taping, or equivalent protections. 1910.254(b)(4)(iv) spells out these methods.

• If a work-only terminal is tied to a grounded enclosure, it must be connected with a conductor at least two AWG sizes smaller than the grounding conductor and clearly marked as grounded, per the same paragraph.
• Regularly inspect covers and insulation for wear to maintain protection.

Portable control devices carried by operators must not be connected to an a.c. circuit over 120 volts, and exposed metal parts of devices operating above 50 volts must be grounded via the control cable. 1910.254(b)(4)(v) requires these limits.

• Use control cables with an internal grounding conductor when device circuits exceed 50 volts.
• Ensure push-button or pendant controls conform to the 120-volt maximum for a.c. supply to portable operator devices.

No, auto transformers or a.c. reactors must not be used to draw welding current directly from any a.c. power source with voltage exceeding 80 volts. This prohibition is stated in 1910.254(b)(4)(vi).

• Use proper welding power conversion equipment designed for supply voltages rather than tapping via autotransformers or reactors when above 80 volts.

The frame or case of a welding machine (except engine-driven machines) must be grounded as prescribed in Subpart S electrical rules. 1910.254(c)(2)(i) requires grounding of machine frames.

• Follow Subpart S grounding methods referenced in 1910.254(c)(1).
• Check mechanical strength and electrical adequacy of ground connections as required in 1910.254(c)(2)(v).

No, conduits must not be used to complete a work-lead circuit, and pipelines, chains, wire ropes, cranes, hoists, and elevators must not be used to carry welding current as a permanent measure. 1910.254(c)(2)(ii) and 1910.254(c)(2)(iii) prohibit these practices.

• Pipelines may be used temporarily during construction or repair only with precautions (no current through threaded/flanged/caulked joints and measures to avoid sparking), per 1910.254(c)(2)(ii).
• For structures regularly used as returns, bond joints or provide current-collecting devices as required in 1910.254(c)(2)(iv).

Each welding machine that does not have an integral disconnect must have a disconnecting switch or controller at or near the machine meeting Subpart S, and supply conductors for individual machines must have ampacity at least equal to the machine's rated primary current. See 1910.254(c)(3)(i) and 1910.254(c)(3)(ii).

• Overcurrent protection must follow Subpart S as noted in 1910.254(c)(3).
• For groups of machines, size conductors based on expected simultaneous loading per 1910.254(c)(3)(iii).

When several welders work on one structure, all d.c. machines must be connected with the same polarity and all a.c. machines connected to the same phase and instantaneous polarity to avoid high no-load voltages between electrode holders. This is required by 1910.254(c)(3)(iv)(A) and 1910.254(c)(3)(iv)(B).

• Be aware no-load voltages between holders can be multiples of normal when mixed polarities or phases are present, per 1910.254(c)(3)(iv).

Before starting, operators must check all machine connections, ensure the work lead is firmly attached, free magnetic clamps from spatter, and spread out coiled welding cable to prevent overheating. These checks are required by 1910.254(d)(2).

• Inspect leads, clamps, and insulation for damage per 1910.254(d)(9)(iii).
• Ensure grounding connections are secure as reminded in 1910.254(d)(3).

Machines that have become wet must be thoroughly dried and tested before being used. 1910.254(d)(9)(ii) requires this, and 1910.254(d)(3) reminds employers to check grounding and safety ground connections for portable machines.

• Do not use wet equipment until insulation resistance and grounding have been verified by qualified personnel.

Electrode holders must be stored so they cannot contact people, conductive objects, fuel or compressed gas tanks, and cables with splices within 10 feet of the holder must not be used; welders must not coil electrode cable around their bodies. These rules are in 1910.254(d)(7) and 1910.254(d)(8).

• Keep electrode holders on insulated racks or hooks away from fuel/pressure vessels.
• Replace cables with splice locations too close to the holder as required by 1910.254(d)(8).

Cables with damaged insulation or exposed conductors must be replaced, and joining lengths of work and electrode cables must use connecting means specifically intended for that purpose with insulation adequate for service conditions. This is required by 1910.254(d)(9)(iii).

• Use factory-rated connectors or listed splices designed for welding currents and insulating conditions.
• Do not use improvised or poorly insulated connections that could expose workers to shock or overheating.

Workers operating or maintaining arc welding equipment must be familiar with this section and with the welding, cutting, and brazing rules in [1910.252(a), (b), and (c)]. 1910.254(d)(1) requires this knowledge.

• Review 1910.252(a), 1910.252(b), and 1910.252(c) for fire prevention, ventilation, and other hazards.

Standard machines must carry rated load where cooling air temperature does not exceed 40 °C (104 °F) and altitude does not exceed 3,300 feet, and must be suitable for atmospheres containing welding gases, dust and rays; unusual conditions like corrosive fumes, humidity, oil vapor, flammable gases, vibration, dust, weather, and shipboard exposure require specially designed machines. See 1910.254(b)(2)(i) and 1910.254(b)(2)(ii).

• Match equipment enclosure, cooling, and corrosion resistance to site conditions.
• Specify sealing, special insulation, or modified cooling for humid, oily, or marine environments listed in 1910.254(b)(2)(ii)(A)-(H).

Control apparatus on arc welding machines must be enclosed except for operating wheels, levers, or handles, and input power terminals, tap devices, and live metal parts of input circuits must be completely enclosed and accessible only by tools. These requirements are in 1910.254(b)(4)(ii) and 1910.254(b)(4)(iii).

• Keep access panels locked or secured and provide only tool access to live terminals to prevent accidental contact.

Employers must ensure proper switching equipment exists to shut down machines and must strictly follow the manufacturer's printed operation and safety instructions. These duties are described in 1910.254(d)(5) and 1910.254(d)(6).

• Maintain accessible emergency stops or disconnects per 1910.254(c)(3)(i).
• Keep and follow manufacturer's troubleshooting and maintenance guidance to reduce hazards.

When welding with alternating current in wet conditions or warm surroundings where perspiration may occur, the use of reliable automatic controls that reduce no-load voltage is recommended to reduce shock hazards. This recommendation is in 1910.254(b)(3)(iv).

• Consider machines with no-load voltage reduction (NLVR) or similar control features to lower shock risk during idle periods and operator adjustments.

Operators should report any equipment defect or safety hazard to their supervisor and discontinue use until the equipment is made safe, and repairs must be done only by qualified personnel. 1910.254(d)(9)(i) requires this.

• Implement a clear defect-reporting process and tag-out unsafe machines until a qualified technician repairs and tests them.