Meters and troubleshootingQuestion 730 of 1506

A 3 to 15 PSI pneumatic scale is used. The air supply fails and the indicator sees 0 PSI. What does the indicator read?

0 percent, the normal low end
25 percent, a normal low value
−25 percent, a clear fault
3 percent, near the low end

Show answer

Correct answer: −25 percent, a clear fault

0 PSI is below the 3 PSI zero point by 3 of the 12 PSI span, which is −25 percent.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 9.1: Analog and Digital Signals

Questions last reviewed: 18 October 2026

Red Seal Electrician Practice needs JavaScript to run. Use its questions for practice. The real pass mark is usually 70%. Check it with your province or territory's apprenticeship office.