Exam prep · UK
PTS AC overhead lines practice questions
25 kV OLE, the 2.75 m rule, bonds, the ECO, permits and rescues.
Updated 8 November 2026 for the latest Rule Book
Key rules
See all 57 key rulesOn OLE lines, the normally live parts of the OLE operate at 25 kV (25,000 volts AC).
RT3170 Iss 11 (2024) §1.4
Where trams or metro trains use the line, OLE may supply up to 750 volts DC.
RT3170 Iss 11 (2024) §1.4
You must not go on or near the line in an area with OLE unless your Sentinel card/PTS certificate includes the qualification PTS AC (valid on lines electrified by the overhead system).
RT3170 Iss 11 (2024) §1.4
An electrified line of route may still include lines or sidings with no overhead line equipment, and it may have unwired sections.
RSSB Rule Book Briefing Iss 43 (June 2026) §2
On an unwired section of electrified line, the same precautions must be taken for rails and bonds as elsewhere, because the same risks arise.
RSSB Rule Book Briefing Iss 43 (June 2026) §3.3
Where new OLE is installed or electrification is extended, the HB16 instructions apply once the equipment is declared live, and you will be told about this in an energisation warning notice.
GERT8000-HB16 Iss 7 §2
If you are not sure whether the OLE is live, you must treat it, and anything in contact with it, as live and dangerous to life.
GERT8000-HB16 Iss 7 §2
OLE, pantographs and roof-mounted electrical equipment on trains are dangerous; touching or going near them, or letting anything touch or go near them, may be fatal.
GERT8000-HB16 Iss 7 §3.1
You must treat all parts shown in red on the OLE diagrams as live at all times unless they have been made safe as the instructions describe.
GERT8000-HB16 Iss 7 §4
Even if you are told the ECO has confirmed the electricity is switched off, you must still treat the OLE, pantographs and roof-mounted equipment as dangerous and must not touch them.
GERT8000-HB16 Iss 7 §4
You need not treat the OLE as dangerous if an overhead line permit has been issued to the COSS stating that the OLE is isolated and earthed.
GERT8000-HB16 Iss 7 §4
Where local isolation is allowed, you need not treat the OLE as dangerous if you are sure it is isolated and earthed and an electrical safety document has been issued under the local instructions.
GERT8000-HB16 Iss 7 §4
Sample questions
1. On a main line railway electrified by overhead line equipment (OLE) for trains, what voltage do the normally live parts carry?
- 750 volts DC
- 25,000 volts AC
- 11,000 volts AC
- 650 volts DC
Answer: B. 25,000 volts AC
OLE supplying trains carries 25,000 volts (25 kV) AC. Up to 750 volts DC is only found where trams or metro trains use the line. Either voltage can kill, but 25 kV can jump a gap, which is why you must keep well clear.
- 750 volts DC: Up to 750 V DC applies only where trams or metro trains use the line.
- 11,000 volts AC: 11,000 V is not the OLE voltage for trains.
- 650 volts DC: 650 V DC is not the OLE voltage for trains.
Source: RT3170 Iss 11 (2024) §1.4
2. Your new job is on a line with OLE. Which qualification must your Sentinel card show before you go on or near that line?
- PTS DCCR
- PTS only, with no extra module
- PTS AC
- COSS
Answer: C. PTS AC
You may only go on or near a line with OLE if your Sentinel card includes PTS AC. The AC module covers the specific dangers of overhead lines.
- PTS DCCR: PTS DCCR covers conductor rail lines, not OLE.
- PTS only, with no extra module: Basic PTS alone does not allow you on or near OLE lines.
- COSS: COSS is a role, not the AC qualification.
Source: RT3170 Iss 11 (2024) §1.4
3. You are carrying a long bar under live OLE. How close may you, or the bar, come to the OLE in any direction?
- No nearer than 600 mm (2 ft)
- No nearer than 1.25 m (4 ft)
- No nearer than 3 m (10 ft)
- No nearer than 2.75 m (9 ft)
Answer: D. No nearer than 2.75 m (9 ft)
You and anything you hold or carry must not come nearer than 2.75 metres (9 feet) in any direction to live OLE, pantographs or roof-mounted equipment. Electricity at 25 kV can arc across a gap, so the distance applies to tools as well as your body.
- No nearer than 600 mm (2 ft): 600 mm is the rescue clearance once power is switched off, not for live OLE.
- No nearer than 1.25 m (4 ft): 1.25 m is not the distance for live OLE.
- No nearer than 3 m (10 ft): 3 m is a near-miss; the rule is 2.75 m.
Source: GERT8000-HB16 Iss 7 §4.1
4. Which must all be true before you work within 2.75 m (9 ft) of live OLE? Select all that apply.
- A method statement or company instruction is in place beforehand
- All precautions it specifies are in place
- You carry out those precautions
- Your COSS has given verbal permission, which is enough on its own
- A lookout is posted to watch the OLE
Answer: A. A method statement or company instruction is in place beforehand, B. All precautions it specifies are in place, C. You carry out those precautions
Working within 2.75 m of live OLE is only allowed if a method statement or company instruction is in place beforehand, all its precautions are in place, and you carry them out. Without all three, the 2.75 m limit stands.
- Your COSS has given verbal permission, which is enough on its own: Verbal permission from the COSS does not replace a method statement or company instruction.
- A lookout is posted to watch the OLE: A lookout warns of trains; it is not a condition for working near live OLE.
Source: GERT8000-HB16 Iss 7 §4.1
5. You need to move a length of rail-side pipe along the cess under OLE. How must you carry it?
- Upright, so it stays clear of the track
- Horizontally, getting others to help if needed
- On your shoulder, pointing upwards at an angle
- Upright, as long as it is under 3 m long
Answer: B. Horizontally, getting others to help if needed
In an OLE area long items must be carried horizontally, with help from others if necessary. Carrying them upright or at an angle could bring them within reach of the live wires.
- Upright, so it stays clear of the track: Carrying upright brings the top towards the live OLE.
- On your shoulder, pointing upwards at an angle: Pointing it upwards risks coming too close to the OLE.
- Upright, as long as it is under 3 m long: There is no length exemption; long items go horizontally.
Source: GERT8000-HB16 Iss 7 §4.3