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EQUIPMENT DAMAGE FROM LIGHTNING INDUCED GROUND POTENTIAL RISE (GPR) RESULTS FROM THE LACK OF PROPER SINGLE POINT GROUNDING (SPG) AND ISOLATION OF POWER AND DATA CIRCUITS FROM REMOTE GROUND

EXECUTIVE SUMMARY:

Equipment damage from lightning induced GPR is totally preventable with engineering design of the grounding system, correct bonding of the equipment to ground bars, and isolation of equipment from other ground planes.

Too often, communication companies fail to take steps to protect their assets from lightning and ground potential rise damage assuming that their infrastructure insurance will cover their losses. However, it often takes months for insurance providers to respond to claims and there is almost always unforeseen residual damage to electrical equipment which will not reveal itself for six months or more following an event.

It is very important to understand that equipment damage is actually the lesser part of your troubles and cost to your company. The greatest cost component to a lighting strike or GPR event is ‘downtime’ followed by increased maintenance cost as a close second. As a rule of ‘thumb’ you can triple your equipment damage cost from a lightning strike to estimate total financial damages. In some cases, client anger from their own business downtime that results from your downtime may much more than triple your eventual damages. Many a communication tower has been abandoned following a single lightning strike.

RECOMMENDED SOLUTION:

Nearly all electrical equipment damage from lightning may be placed into two categories; improper site grounding from lightning induced GPR, and the failure to isolate equipment circuit connections to a remote ground plane.

There are no codes available in print today that recommend protection of equipment from lightning strike energy. However, IEEE Standard 1692-2011 is available and expertly details methods for the protection of equipment from a lightning strike.

Current available recommendations from other sources are very sketchy, provide little or no support, and rarely is GPR mentioned. When GPR is sometimes alluded to, shunting devices such as gas tubes, MOV's, and SCR's are recommended as possible solutions. Sources not providing necessary information to design against lightning induced GPR include NEC, NESC, and NFPA 780, and Motorola’s Standards and Guidelines for Communication Sites (R56 Issue B).

Shunting devices will not protect electronic equipment from a GPR, whether induced from lightning or from a power line earth return fault. Shunting devices merely offer an additional path off the site to remote ground and guarantee a connection to the communication path in the reverse direction from which they were intended to operate. This of course also guarantees the destruction of your equipment.

Since the elimination of the remote ground path (copper communications wires) may not be a reasonable solution, why not the next best thing? Isolate the wire-line conducting path. Remember that this only one part of a two-part solution. Proper bonding and grounding of equipment is the other part of your solution.

The single most important solution of equipment damage from lightning induced GPR, is the utilization of a Single Point Ground (SPG) and a capacitively coupled radial grounding system. If the SPG is not considered or placed correctly, you can expect equipment damage to plague you forever, even with a perfectly designed radial grounding system.

LPGI & Affiliates has 42 years of professional experience in all types of grounding and electrical protection from lightning. We are your answer to the very expensive downtime that may occur with your next lightning strike. Cellular tower sites, TV Antenna sites, radar sites, wind farms, substations and power plants are our specialty.

Our consulting fee with AutoCAD Drawings and a step by step procedure on the resolution of your lightning issues will be a fraction of your total cost to your next lightning strike.


LPGI & Affiliates
962 Coronado Drive
Sedalia, CO 80135-8303
303-688-5800
Fax: 303-688-5551

 

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