[ Index ]
[ Index ]
Here are some ideas and hints to approach a proper ISBP. The basic idea is to keep people safe indoors while diverting away any potentially dangerous voltage differences or flashover to the outside by the most expeditious means possible.
The ISBP suite is, generally speaking, an outdoor device. The strongest criteria for locating this "outdoor" device is not that it be installed outdoors; rather, the ISBP is supposed to prevent potential differences from occurring indoors where vulnerable animals and people occupy space on a normal basis. Heat, potential differences, lightning, electrical power surges, and high current flows must all flash over and balance out at a safe location away from occupancies, which is why we associate the ISBP as an "outdoor" device. Not only does the ISBP serve as the safe location, it strengthens the grounding cone of protection around the occupants. ISBP protects occupants. ISBP protects people.
One way is to line up ISBP suite modules along the GEC.
Try to configure the GEC as an indoor installation, perhaps underneath the occupancy spaces of the facility. A protected, non-occupant space such as an electrical enclosure ( e.g., box, conduit body, raceway ), crawlspace, basement, or enclosed awning would be ideal for routing the GEC.
This facilitates the use of indoor construction techniques and materials for protecting the GEC and for creating an ISBP with readily available materials. Place the ISBP suite along the path of the GEC so that the GEC passes through the ISBP on its way to the GES. Give access to the ISBP that is comparable to the access provided to the ESE. Changes should be easy to do.
The argument can be proffered that with an ideal, or strong, ISBP suite in place between the ESE and the grounding electrode, there is little justification for placing additional ISBPs. One ISBP "should be" enough. Such an argument asserts that any additional ISBP would offer no additional benefit except in a direct or nearby lightning strike, or electromagnetic pulse (EMP) event. In any case, an additional ISBP requires double the materials, double the labor, and double the time required.
The problem with this argument is that it hinges on having 100% of services and systems sponsored at the lone ISBP, which is rare in the real world. In fact, it is so rare that the National Institute of Standards and Technology saw fit to partner with the electrical and insurance industries to publish a consumer guide (Special Publication 960-6) on a combined solution that uses indoor and outdoor ISBPs. The strongest argument put forth by NIST is that the protection to individual computers, consumer electronics, and high-value appliances must be installed at the point of connection to the device in order to ensure that the protection extends to person(s) using the device during the event when that protection is needed. The paramount concern is safety of life through mitigation of hazards that are electrical or fire related. As far as practical, any two ISBPs serving the same facility must be bonded together with a dedicated jumper (or through the ESE grounding system or GEC) when they are both on the same side (supply or load) of the ESE.
An ISBP for only one system is unable to function as an ISBP; rather, it is only functioning as a glorified grounding means or bonding jumper. A minimum of two services must be sponsored before it can be called an ISBP.
Any ISBP is better than none, even a weak or poorly constructed one.
Conversion over time from a weak ISBP to a strong one is preferred to having no ISBP at all.
In the absence of an "outdoor" ISBP, defined here as a multi-system bonding integrator installed between the ESE and the GEC, an "indoor" version would contribute protection by integrating missing systems.
Because the GEC resolves potential differences, the GEC is constantly carrying electrical current flow. This constant change of current flow, or flux, can be described as "noisy." However, this necessary noise on the GEC and the GES becomes manifested as "quiet" inside the served facility on the load side of the ESE.
Quiet happens indoors because there is only one GEC bonded to the ESE, and because there is a geographical separation (meaning air and other insulation) between the "indoor" facility and the GES.
The GEC and GES are installed in close proximity to the earth, if not underground. This forces the GEC and GES to electrically behave as if they were part of the earth. If current flow exchange is kept close to ground, then the earth absorbs the noise and acts as a protective shield for such noise.
How much shielding and protection are really in the grounding cone of protection? With ISBP in place, an appreciable amount. With ISBPs in place both indoors and outdoors, there is even more. Without ISBP, hardly any will exist because incoming services will all go in their own paths, piercing the protective boundary and contaminating the interior with unbalanced voltage. There are too many nonconductive gaps such as air and brick and mortar that permit electromagnetism and lightning effects to pass through.
The more the ISBP is implemented, the more a facility behaves as a Faraday box shield around its occupants. This is similar to the Earth's magnetosphere that protects us from harmful solar and cosmic energy.
The ESE and ISBP together begin to form an electrical copy of a Faraday box, which gets stronger and more complete as the facility is more complex along its GES and ISBP.
The inclusion of all available grounding electrodes, especially structural steel and water mains, will greatly enhance the Faraday effect. This is where the grounding cone of protection gets its teeth.
The grounding cone of protection becomes more pronounced, more robust, and more effective when the following events occur:
Consider employing an isolated ground technique under these circumstances:
Consider employing a meshed grounding technique under these circumstances:
Meshing of bonding jumpers and grounding wires on the exterior of a facility is best made at the ISBP where all connections may be easily checked for periodic improvements and repair.
Meshing will electrically solidify the boundary of the grounding cone of protection.
Metallic exterior sections of the facility will enhance the boundary of the grounding cone of protection when meshed and bonded to the ISBP. Roofing, walls, doors, and flooring should be bonded to the ISBP if they are conductive. This includes conductive materials placed on a portion of their surfaces.
Bond adjacent edges of metallic surfaces together. Ensure that the bonds eventually trace back to the ISBP.
Parallel grounding paths back to the ESE through sub-panels is achieved with EMT conduit installed as a system while also using grounding wires and bonding jumpers. This is highly encouraged. Additional pathways with more bonding jumpers and grounding wires is also encouraged as they will enhance the grounding cone of protection.
Persons and animals occupying facilities will benefit from having an ISBP, regardless of their purpose. An ISBP must be created, used, and updated over time in order to continue its effectiveness and protection for the consumer.
[ Index ]
