HAZARDOUS AREA EQUIPMENT SUPPLEMENT FEATURE
MOBILE TRUCK GROUNDING Earthing hazardous trucks safely
Mike O’Brien, head of product marketing for Newson Gale, offers his advice on how you can safely earth a truck in an area where there is no earthing system in place
risk of ‘false’ earthing points being mistakenly used by the driver. By simply connecting the MGV’s clamp to the earthing point, the MGV automatically verifies if the earthing point has a connection to the general mass of the Earth that will prevent the build of static charges on the truck. Not only does the MGV ensure the
truck is connected to a true Earth ground, it also monitors the truck’s connection to the verified ground for the duration of the transfer operation. Structures and equipment that are in permanent contact with the ground, such as support beams, motor casings and fences, can be tested to provide a grounding point for the truck. Even in situations where such options are not present, a temporary ground can be tested and established with a set of ground rods. The truck mounted grounding system, the Earth-Rite MGV, tests earthing points to ensure that they are capable of earthing trucks. Should the MGV detect a
compromised ground connection, two volt-free (dry) contacts facilitate the shutdown of the transfer operation, preventing the generation and
T
rucks transferring flammable products require static grounding
protection to prevent the build-up of static electricity on the truck or equipment, like hoses, that are connected to the truck. If static electricity is allowed to build up on the truck, the discharge of a static spark becomes a very real but unseen ignition hazard. In terminals equipped with loading racks, static grounding systems ensure static electricity cannot accumulate on the truck during loading or unloading. However, many trucks recovering or
transporting flammable product conduct transfer operations in locations where static grounding systems are not present. This is mostly due to the nature of the operation, which could range from cleaning out a storage tank to delivering products to sites where grounding systems are not installed at the product delivery point.
Above: The truck mounted grounding system, the Earth-Rite MGV, tests earthing points to ensure they are capable of earthing trucks
Right: The Earth-Rite MGV ensures the resistance to True Earth is low enough to safely ground the truck
In situations where grounding systems are not present, grounding is usually achieved with a cable reel that bonds the truck to what is assumed to be a functional grounding point. However, it is impossible for a bonding reel to determine if the earthing point will in fact transfer electrostatic charges to earth. It is also not possible to monitor the truck’s connection to the earthing point for the duration of the transfer operation. This is risky as the driver will not know if the grounding clamp connection is compromised unless he has a visual confirmation of this. A truck mounted system, such as the Earth-Rite MGV, removes the
subsequent accumulation of static electricity. This feature, combined with the bright attention grabbing LED earth status indicators, ensures the safety of the operation is enhanced well above the levels provided by basic bonding reels.
Newson Gale
www.newson-gale.co.uk
ELECTRICAL ENGINEERING | APRIL 2016 S9
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