What equipment selection, installation, and grounding requirements does 29 CFR 1910.254 impose on arc welding and cutting equipment? Answer in under 100 words. Cite only eCFR (www.ecfr.gov) sources.

Equipment selection

Employers must choose welding equipment for safe application to the specific welding or cutting task to be performed [ref_id 1]. Assurance of safety in design is obtained by selecting apparatus complying with NEMA EW-1-1962 (Requirements for Electric Arc-Welding Apparatus) or ANSI C33.2-1956 (Safety Standard for Transformer-Type Arc-Welding Machines), both incorporated by reference [ref_id 1].

Voltage limits

Higher-voltage special processes require adequate insulation or other means preventing operator contact, and reliable automatic no-load voltage reduction controls are recommended for AC welding in wet conditions or where perspiration is a factor [ref_id 1].

Installation & grounding requirements

• Installation, including power supply, must comply with Subpart S of 29 CFR Part 1910 (Electrical standards) [ref_id 1].
• The frame or case of each welding machine (except engine-driven machines) must be grounded under the conditions and methods prescribed in Subpart S [ref_id 1].
• All ground connections must be checked to confirm they are mechanically strong and electrically adequate for the required current [ref_id 1].
• Conduits containing electrical conductors must not be used to complete a work-lead circuit; pipelines may be used only temporarily during construction, extension, or repair, provided current does not pass through threaded, flanged bolted, or caulked joints [ref_id 1].
• Chains, wire ropes, cranes, hoists, and elevators must never be used to carry welding current [ref_id 1].
• A disconnecting switch or controller must be provided at or near each machine lacking an integral switch, with overcurrent protection per Subpart S [ref_id 1].

Exceptions & edge cases

• Engine-driven welding machines that are not connected to a supply circuit are exempt from the frame-grounding requirement [ref_id 1].
• Pipelines may serve a work-lead circuit on a temporary basis during construction, extension, or repair if special precautions avoid sparking at the work-lead cable connection [ref_id 1].
• Structures, conveyors, or fixtures regularly used as a welding return circuit must have joints bonded or fitted with adequate current-collecting devices [ref_id 1].
• For multiple welders on one structure, all DC machines must share the same polarity, and all AC machines must connect to the same supply phase with identical instantaneous polarity [ref_id 1].