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Effect of a poor ground connection in arc welding

Aviation Mechanic Airframe (AMA) practice question 10 of 20 on Metallic Structures. ACS element AM.II.A.R4 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONWhat is the result of a poor ground connection when using electric arc welding equipment?

  1. AA fluctuating, hard-to-control arc
  2. BRapid burning of the electrode holder
  3. CAn arc that cannot be struck at all
Show the answer and explanation

Correct answer: A. A fluctuating, hard-to-control arc

  • A — correct The handbook warns that a poor ground connection results in a fluctuating arc that is difficult to control.
  • B — incorrect Damage to the holder is not the stated consequence; the effect described is on the stability of the arc itself.
  • C — incorrect The arc still forms, but it wanders and fluctuates rather than failing to establish.

BACKGROUND

The first step in preparing to arc weld is to make certain the necessary equipment is on hand and that the welding machine is properly connected and in good working order. Particular attention should be given to the ground connection, since a poor connection results in a fluctuating arc that is difficult to control. When a shielded electrode is used, its bare end is clamped in the holder at a 90 degree angle to the jaws, although some holders allow 45 degrees for other welding positions. Before striking an arc, the mechanic runs through a checklist: that the proper personal safety equipment is in use, including a welding helmet, welding gloves, protective clothing, and footwear, with appropriate breathing equipment if the area is not adequately ventilated; that the ground is properly connected to the work piece; that the correct type and size of electrode is selected and properly secured; that machine polarity matches the electrode; and that the machine is adjusted to provide the necessary current.

STUDY TIP

Run through the pre-weld checklist in order when answering arc welding questions. Ground quality, electrode selection, polarity, and current setting each have their own symptom when wrong.

KEY POINTS

  • A poor ground connection produces a fluctuating arc that is hard to control.
  • A shielded electrode is normally clamped at 90 degrees to the holder jaws.
  • Check protective equipment, ground, electrode, polarity, and current before striking an arc.

SOURCES

  • sources/ama-airframe/ch05.txt "Welding Safety Equipment"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-31B Aviation Maintenance Technician Handbook – Airframe, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.