Exam prep · UK
PTS DC conductor rail practice questions
750 V conductor rail, the 1.5 m rule, crossing safely, isolations and rescues.
Updated 8 November 2026 for the latest Rule Book
Key rules
See all 75 key rulesOn conductor rail lines, step over the running rail and conductor rail together; you must never step or put your foot between the conductor rail and the adjacent running rail.
GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §4
On conductor rail lines, cross where protective guarding has been provided if possible.
RT3170 Iss 11 (2024) §4.7
A conductor rail (third rail) supplies up to 750 volts DC and is raised above the running rail on plastic or ceramic insulators.
RT3170 Iss 11 (2024) §1.4
On lines used by London Underground trains there is a further conductor rail in the four-foot, called the fourth rail.
RT3170 Iss 11 (2024) §1.4
You must not go on or near the line in an area with conductor rail equipment (CRE) unless your PTS competence includes DC electrified lines (Sentinel qualification PTS DCCR).
GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §2
CRE, shoe gear and associated exposed live train-mounted equipment must be treated as live at all times unless one of the listed exceptions applies.
GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §3.1
If you are not sure whether the CRE is live, you must treat it as live and dangerous to life.
GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §2
Touching or going near CRE, shoe gear or under-floor electrical equipment on trains may be fatal.
GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §3.1
One exception to treating CRE as live is a planned isolation with a conductor rail permit issued to the COSS.
GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §3.1
Other exceptions to treating CRE as live are a temporary isolation taken under the infrastructure manager's instructions, or a local isolation taken under local isolation instructions.
GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §3.1
In an emergency, if the ECO has confirmed the CRE is switched off and local staff tell you it is safe, you may approach the CRE but must not touch it.
GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §3.1
You must not touch or step on CRE, shoe gear, associated exposed live train-mounted equipment or guard boarding.
GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §4
Sample questions
1. You need to cross a conductor rail line and there is no protective guarding nearby. How must you cross?
- Step on the conductor rail's guard boarding to get across
- Step over the running rail, then put a foot down before the conductor rail
- Step over the conductor rail and adjacent running rail together
- Step between the two rails, then over the conductor rail
Answer: C. Step over the conductor rail and adjacent running rail together
On conductor rail lines you step over the conductor rail and the running rail next to it together, never putting a foot between them. Where possible, cross at a place with protective guarding.
- Step on the conductor rail's guard boarding to get across: You must never step on guard boarding.
- Step over the running rail, then put a foot down before the conductor rail: This puts your foot between the conductor rail and running rail, which is forbidden.
- Step between the two rails, then over the conductor rail: Stepping between the conductor rail and adjacent running rail is never allowed.
Source: GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §4; RT3170 Iss 11 (2024) §4.7
2. Unless special conditions apply, what is the closest you, or anything you hold, may come to live conductor rail equipment?
- 300 mm (1 foot)
- 1.5 metres (5 feet)
- 2.75 metres (9 feet)
- 3 metres (10 feet)
Answer: B. 1.5 metres (5 feet)
You and anything you are holding must stay at least 1.5 metres (5 feet) from live conductor rail equipment, shoe gear and live train-mounted equipment. Going closer needs specific approved precautions.
- 300 mm (1 foot): 300 mm is the point where a conductor rail shield is needed during approved live working.
- 2.75 metres (9 feet): This is not the DC conductor rail distance; it is 1.5 metres.
- 3 metres (10 feet): Too far; the rule is 1.5 metres (5 feet).
Source: GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §4
3. Company instructions allow live working. Your task will bring your tools within 300 mm of the live conductor rail. What must you do first, if possible?
- Apply a short-circuiting bar to the conductor rail
- Place detonators on the rail furthest from the conductor rail
- Ask the lookout to watch your tools
- Place a conductor rail shield over the conductor rail
Answer: D. Place a conductor rail shield over the conductor rail
If you or anything you hold will be nearer than 300 mm (1 foot) to live conductor rail, you must if possible fit a conductor rail shield first. The work also needs approved insulated tools, shrouds or troughing, PPE and a valid safe system of work.
- Apply a short-circuiting bar to the conductor rail: A short-circuiting bar is only for emergencies when someone is in danger and the ECO cannot be reached.
- Place detonators on the rail furthest from the conductor rail: Detonators protect against trains, not against electric shock.
- Ask the lookout to watch your tools: A lookout warns of trains; they do not protect you from live equipment.
Source: GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §4
4. Your COSS asks you to apply a track-circuit operating clip on a conductor rail line. Which rail do you clip on first?
- The running rail furthest from the conductor rail
- The running rail nearest the conductor rail
- Either running rail, the order does not matter
- Both running rails at the same moment, using two people
Answer: A. The running rail furthest from the conductor rail
On conductor rail lines, a track-circuit operating clip or T-COD goes on the running rail furthest from the conductor rail first, then the rail nearest it. This keeps you away from the live rail for as long as possible.
- The running rail nearest the conductor rail: The nearest rail is clipped second, not first.
- Either running rail, the order does not matter: The order is set and must be followed.
- Both running rails at the same moment, using two people: The rule sets a clear order: furthest rail first, then nearest.
Source: GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §4
5. True or false: when removing a track-circuit operating clip on a conductor rail line, you take it off the rail furthest from the conductor rail first.
- True
- False
Answer: B. False
Removal is the reverse of fitting: take the clip off the rail nearest the conductor rail first, then the rail furthest from it. Getting the order wrong can put you at risk near the live rail.
Source: GERT8000-HB17 Iss 6 (in force 6 Jun 2026) §4