12 April 2002

HSEsays drivers of big combines face electrocution risk

SOME of the biggest combine harvesters are now so large that drivers could be exposed to the risk of electrocution when working under overhead power lines – lines which can carry up to 400,000V.

The warning comes from the Health and Safety Executive, which says the risk has increased because modern high-output combines are bigger than previous models. The problem is further compounded through use of upward opening grain tank lids, a design now adopted by most makers.

In one case, checked by the HSE, the overall height with the grain tank lid raised was 5.2m which, frighteningly, just equals the minimum height for overhead power lines, says Andrew Williams, HSE principal inspector.

"But combines do not have to be 5.2m high to be at risk," he says. "Some overhead cables are lower than they should be and the problem increases when hot weather makes them expand and sag. Even without actual contact, the combine may be close enough for a current to arc from the cables.

"The HSEs view is that machines above about 4.7m overall working height could be at risk, putting several modern harvesters on the danger list."

Britain faces the biggest problem of excess machine height, as power lines are higher in most European countries, and in the US they follow roads or railways and rarely cross open fields, points out Mr Williams.

"The solution is to raise the height of the power lines, but in the short term combine manufacturers could reduce the risk by using non-conducting plastic for the grain tank covers," he says.

HSE advice for farmers with power lines crossing their land is to ensure drivers of combines and other high machines – forage harvesters and sprayers with vertically folded booms, for example – are aware of the danger. Lowering the grain tank covers while passing under the power line will reduce the overall height, but if an electricity strike occurs, the driver should follow these guidelines:

lRemain in the cab and drive away from the danger area. This will not be possible if the power surge has destroyed the combines electrical systems.

lUse a mobile phone to get help.

lIf you must leave the cab, remember the biggest risk of electrocution is while touching both the ground and the combine. Jump from the steps, landing on both feet and as far as possible from the combine.

lKeep others away from the combine until you are certain the power is switched off. &#42

Drivers of large combines could be exposed to the risk of electrocution when working under overhead power lines, warns the HSE.