4.2 AC Clearances, Live Equipment, Bonds & Overhead Line Permits
Key Takeaways
Treat OLE, pantographs and roof-mounted electrical equipment as live at all times unless an overhead line permit or local isolation assurance says the equipment is isolated and earthed.
You and anything you are holding must not come nearer than 2.75 metres (9 feet) in any direction to live OLE unless a method statement or company instruction applies and its precautions are in place.
Each OLE structure has a black bond to the running rail; there are also yellow and red bonds, and all bonds must be treated as dangerous and never touched.
Report a disconnected, broken or defective bond to the ECO immediately, stating its colour and location; first tell the signaller if train safety is affected.
An overhead line permit (Form C) is issued by the Nominated Person to the COSS; it states what is isolated and earthed and does not mean that train movements have stopped.
4.2 AC Clearances, Live Equipment, Bonds & Overhead Line Permits
In an AC electrified area, your safety depends on two habits: treat everything as live and keep your distance. The rules come from Rule Book Handbook 16, AC electrified lines (GERT8000-HB16; Issue 7 has been in force since 6 June 2026), and from section 1.4 of the PTS handbook (RT3170).
Treat the Equipment as Live
HB16 says OLE, pantographs and associated roof-mounted electrical equipment on trains are extremely dangerous. It may be fatal if you touch or go near any of them, or allow anything to touch or go near them. You must treat them as live at all times unless one of the following applies:
- an overhead line permit has been issued to the COSS stating that the OLE has been isolated and earthed;
- where anyone needs to access a train roof or work near roof-mounted equipment, the permit also includes a declaration that all train and locomotive pantographs and roof-mounted equipment have been isolated and earthed;
- the OLE has been isolated and earthed and an assurance received under local isolation instructions.
If you are told that the ECO has given an assurance that the electricity has been switched off in an emergency, you must still treat the equipment as dangerous and not touch it. Switched off is not the same as isolated and earthed.
The 2.75-Metre (9-Foot) Rule
Important
Keep 2.75 Metres Away You must not carry out any work that will bring you, or anything you are holding, nearer than 2.75 metres (9 feet) in any direction from live OLE, pantographs or associated roof-mounted equipment, unless all of these conditions are met: a method statement or company instruction is in place; all the specified precautions to manage the danger are in place; and you carry out those precautions (HB16 section 4.1).
The PTS handbook puts it for PTS holders: make sure you, and anything you are carrying, do not go within 2.75 metres of live OLE or the electrification equipment on a train's roof, such as the pantograph. In some situations work can take place within 2.75 metres of live OLE, but only if a special safe system of work has been approved beforehand.
live OLE wire
*
. . | . .
. | .
. <--- 2.75 m ---> .
. | .
. . | . .
Nobody, and nothing being carried, comes inside this distance
unless the equipment is isolated and earthed, or an approved
method statement with its precautions applies.
The distance applies in every direction, including upwards. Ladders, poles, measuring staffs, pipes, scaffold tubes and long tools are the usual way people get too close.
Long Items
HB16 section 4.3 requires extreme care when holding and moving long items, using brake sticks and shunting poles, and choosing the correct type of electrically insulated ladder. Carry long items horizontally and, if necessary, get other people to help you.
Working on Vehicles
You, and anything you are holding, must never go above the cant rail level of a vehicle, and you must not climb above the floor level of the driving cab, onto the roof or open upper deck, or onto roof access steps, unless there is no OLE above or next to the vehicle, the OLE and the train's pantographs and roof equipment have been isolated and earthed under a permit, the conditions in your company instructions are met, or a permitted local isolation is in place (HB16 section 4.2).
Objects on or Near the OLE
Treat broken or displaced wires, and anything attached to or near the OLE, as live and dangerous to life. You must not remove or approach anything attached to or near live OLE, and you must not try to remove or approach an object hanging from, touching or close to the OLE unless you have been specially trained and authorised to do so (HB16 section 3.2).
Bonds
The PTS handbook explains that each OLE structure has a black cable connecting it to the running rail. This is known as a bond. There are also yellow bonds and red bonds. Bonds carry traction return current and connect structures to the return circuit, so a disconnected bond can leave a dangerous voltage across the gap.
- All bonds are to be considered dangerous, especially if they become disconnected. Never touch them, as there could be a dangerous voltage.
- Immediately report to the ECO any bond that you find disconnected, broken or defective, and include the colour of the bond and its location.
- HB16 adds that you must not touch rails that are broken or parted, a broken or defective bond that is marked red, or any equipment connected to that bond.
What to Report to the ECO
HB16 section 3.3 lists defects you must make sure are reported to the ECO immediately:
- objects thrown onto, hanging from or otherwise touching the OLE;
- damage to the OLE, or OLE that is smoking, excessively flashing or fusing;
- broken or displaced along-track conductors, or broken or displaced wires connected to the OLE;
- damaged or loose automatic power control (APC) track inductors;
- a broken or parted rail;
- a broken or defective bond, stating its colour.
If the damage or defect will affect the safe operation of trains, report it to the signaller first. Damaged or loose automatic power changeover balises on the approach to an electric to self-powered changeover location must be reported to the signaller.
Overhead Line Permits (Form C)
When work must take place on or near the OLE, the equipment is isolated and earthed and an overhead line permit, traditionally known as Form C, is issued.
- The permit is signed and issued by the Nominated Person (NP) and given to the COSS (or a designated person) who is to work on or near the OLE.
- It states exactly what electrical equipment is isolated and earthed, and on or near which it is safe for the specified work to begin.
- A permit does not mean train movements have stopped. Isolation of the OLE does not stop trains; separate protection is needed for that.
- Isolated OLE must still be treated as live until a permit has been issued (or a local isolation assurance received).
The COSS must understand the working limits, which equipment is live and which is earthed where they cross or run alongside each other, and that the permit does not stop trains. The COSS signs the permit and makes sure everyone in the group understands its conditions before work starts, and briefs anyone who joins later. If the COSS hands over, the permit passes to the new COSS, both sign it, and the NP is told. A lost permit must be reported to the NP, who issues a duplicate.
When work is suspended or finished, the COSS makes sure all people and materials are at least 2.75 metres clear of the OLE, tells everyone to treat the OLE as live again, completes the permit and returns it to the NP, who countersigns it.
| Topic | Rule |
|---|---|
| Live presumption | OLE, pantographs and roof equipment are live unless a permit or local isolation assurance says isolated and earthed |
| Clearance | 2.75 m (9 ft) in any direction, unless an approved method statement and its precautions apply |
| Bonds | Black structure bonds, yellow and red bonds: never touch; report defects to the ECO with colour and location |
| Permit (Form C) | Issued by the NP to the COSS; says what is isolated and earthed; does not stop trains |
Unless an approved method statement or company instruction with its precautions applies, how close may you, or anything you are holding, come to live overhead line equipment?
No nearer than 1.25 metres (4 feet)
No nearer than 2.75 metres (9 feet) in any direction
No nearer than 300 millimetres (1 foot) if wearing insulated gloves
No nearer than 5 metres (16 feet) in every case
What does an overhead line permit (Form C) confirm, and what does it NOT mean?
It states exactly which equipment is isolated and earthed and where work can begin, but it does not mean that train movements have stopped
It confirms that all trains have been stopped, but the OLE may still be live
It is a yearly competence certificate allowing a PTS holder to work on live OLE
It is a lineside board marking the change from AC to DC electrification
You find a disconnected bond at the foot of an OLE structure. What does the PTS handbook tell you to do?
Reconnect it carefully while wearing leather gloves
Move it clear of the walking route with your boot
Do not touch it, and report it immediately to the ECO, including the colour and location of the bond
Leave it, because only red bonds ever carry a dangerous voltage
Sections you finish are checked off in the contents.