PTS Working Near Electrified Lines 5 — Questions and Answers
Question 1: A worker needs to cross over a live electrified third rail. What is the correct method?
- Step over it quickly in one stride
- Use an approved insulated crossing board placed over the rail (Correct answer)
- Jump across to avoid any contact
- Walk along the rail to find a naturally safe crossing point
Correct answer: Use an approved insulated crossing board placed over the rail
An approved insulated crossing board must be placed over the third rail to provide a safe, non-conductive path across it.
Question 2: What is the purpose of a 'short circuit device' applied to an isolated section of electrified track?
- To test if the isolation has been successfully applied
- To provide a visible and functional earth that protects against accidental re-energization (Correct answer)
- To increase the resistance of the rail for signal testing
- To mark the limits of the work zone for other workers
Correct answer: To provide a visible and functional earth that protects against accidental re-energization
A short circuit device provides both a visible indicator and a functional earth connection, ensuring that any accidental re-energization trips protection systems immediately.
Question 3: At what voltage does the US National Electrical Safety Code classify overhead transmission lines as 'high voltage' requiring strict clearance protocols?
- Above 120V AC
- Above 600V (Correct answer)
- Above 1,000V
- Above 5,000V
Correct answer: Above 600V
NESC generally classifies lines above 600V as high voltage, requiring strict minimum approach distances and additional safety protocols.
Question 4: Which of the following is NOT a valid method for confirming electrical isolation before beginning work?
- Verbal confirmation from the electrical control room via radio
- Using a calibrated voltage detector to test the circuit
- Visually observing an open isolator switch in the locked position
- Assuming isolation because no train is scheduled for the next hour (Correct answer)
Correct answer: Assuming isolation because no train is scheduled for the next hour
Assuming isolation based on train schedules is never acceptable — formal confirmation through authorized channels and physical verification is always required.
Question 5: Why must workers avoid touching two conductive objects simultaneously when working near electrified infrastructure?
- It can cause signal interference and delay train operations
- A worker can become part of a circuit if the objects are at different potentials, causing electrocution (Correct answer)
- Double contact increases the risk of dropping tools on the track
- It is a procedural rule with no direct electrical safety basis
Correct answer: A worker can become part of a circuit if the objects are at different potentials, causing electrocution
Simultaneously touching two objects at different electrical potentials completes a circuit through the worker's body, allowing potentially fatal current to flow.
Question 6: What action is required before using any electrical test equipment near a live electrified line?
- Visual inspection of the equipment for obvious damage only
- Verify the equipment is rated for the voltage present and has a current calibration certificate (Correct answer)
- Confirm that a colleague is watching before proceeding
- Ensure the test equipment battery is fully charged
Correct answer: Verify the equipment is rated for the voltage present and has a current calibration certificate
Electrical test equipment must be rated for the voltage level present and must have a valid calibration certificate to ensure accurate and safe readings.
Question 7: During a PTS briefing, a supervisor states that the adjacent line remains live while work proceeds on the isolated line. What must all workers do?
- Ignore the adjacent line since they are only working on the isolated line
- Maintain required clearance from the live adjacent line and avoid any equipment encroachment (Correct answer)
- Request that the adjacent line also be isolated before starting any work
- Assign one worker to watch only the adjacent line while others work freely
Correct answer: Maintain required clearance from the live adjacent line and avoid any equipment encroachment
Workers must maintain required approach distances from any adjacent live line at all times, ensuring no person or equipment encroaches on the live line's danger zone.
PTS Working Near Electrified Lines 5
A worker needs to cross over a live electrified third rail.
What is the correct method?