The Safe Operation Of Cranes Near Power Lines
Overhead power cables can be a major hazard when mobile crane operations have to be carried out in their vicinity. In an average year, there are over 400 serious accidents and 20 deaths in the UK caused by construction or agricultural machinery operating close to, or coming in contact with, underground or overhead power cables.
Actual contact is not required to create an electrical flashover. Electricity can jump the gap between two conductors, one being the HV cable, the other the crane boom, where it can travel down to the cab, often with fatal consequences. Mobile cranes and power lines do not mix, so strict operating parameters and safety precautions should be put in place, in line with all health and safety guidelines and legislation.
Eliminating or minimising the danger of electric shock
Not all high voltage cables come on those tall electricity pylons, commonly seen stretching through fields and across roads. In many instances, especially in industrial parks and other built-up areas, they can be mistaken for telephone lines, with one or two HV cables crossing an area on what appear to be telegraph poles.
Although most poles will carry a plate denoting whether they carry electricity cables or telephone lines, it always pays to double-check. The local electricity board or distribution networker will be able to tell you exactly what the poles carry, and can supply plans of where all underground and over-ground cables run in the area. In many instances, they can cut power, or re-route it, for the duration of the work.
If power can’t be cut, they can supply all the information required regarding how far equipment needs to be kept from the cables concerned, to avoid any risk of electrical flashover, and should always be your first point of contact.
Prepping for work near live power cables
Like all crane operations, the working area needs to be coned or taped off, and open to operating personnel only.
An experienced site/operations manager should be delegated to oversee the operation, with special emphasis on ensuring all regulations on working with cranes near power lines are followed.
If the crane needs to pass under the cables to reach the operating site, look for an alternative route. If there isn’t one, ascertain the clearance required between power lines and crane from the power company, to ensure there is no risk of flashover. For any plant, the shortest route possible should be used to pass under the cables, generally at 90° to the direction of the power lines.
On telescopic cranes especially, physical locks should be added to stop the crane from reaching past the safe close working limit during operations.
If work is being carried out on the limits of the safe zone, personnel should be informed, and no fault fixing should be carried out on the crane’s cab or boom before the machine has moved to a safer area. Wearing rubber gloves, standing on rubber mats, or using wood-handled tools will not necessarily save you from a major electric shock or burns from a flashover.
In the event of heavy rain, operations should be suspended. Water is an excellent conductor of electricity.
Inadvertent contact with HV power cables
Should any part of the boom, hook or load come into contact with a power line without damaging it, shout a warning, and clear the area of all personnel. Study the point of contact, can you solve the problem by rotating the boom, or lowering it away from the cable?
Do not, under any circumstances, attempt this if you feel there is a possibility you will pull the cable away from the pole. The last thing you want is a live cable laying on the ground. In this instance, stay in the cab, contact the electricity company, explain the problem, and they will isolate the line.
If you hit a cable that has caused a cab or fuel fire, do not use the ladder, but jump clear of the vehicle. Clear the area of any and all staff and contact the emergency services, including the power supply company.
Here at Emerson Crane Hire, we offer a range of comprehensive courses for onsite crane operations and crane operation safety. If you have any questions relating to working with mobile cranes and power lines, please contact us today and have a chat with one of our course managers.