Earthing Systems Design steps – Part Seven


In Article 
Earthing Systems Design steps – Part One ", I indicated the following points:





Earthing Systems Design Steps

A grounding system design process has (3) main steps:


  1. Data Collection,
  2. Data Analysis,
  3. Grounding Design Calculations.






In the above Article and Article 
 Earthing Systems Design steps – Part Two ", I explained the first step: Data Collection.

Also, in Article Earthing Systems Design steps – Part Three ", I explained the second step: Data Analysis.


And in Article 
" Earthing Systems Design steps – Part Four ", I explained What we are going to design for grounding system in any building?





What we are going to design for grounding system in any building?

Grounding system in any building can be broken down into several subdivisions:

  1. The building exterior grounds,
  2. The electrical service grounding,
  3. The building interior bonding,
  4. Equipment grounding and bonding,
  5. Lightning protection.



Also in this Article, I explained the Building Exterior Grounds.


In Article 
Earthing Systems Design steps – Part Five ", I explained The electrical service grounding and indicated the five subdivisions of The Building Interior Bonding which were:





The Building Interior Bonding

Building Interior Bonding can be broken down into several subdivisions:

  1. Bonding of Equipment for Services.
  2. Bonding for Other Systems
  3. Bonding Other Enclosures.
  4. Bonding for Over 250 Volts
  5. Bonding of Piping Systems and Exposed Structural Steel.
  6. Bonding of Interior Metal Columns and Beams





And I explained the first three subdivisions in this article. 


Also in Article " Earthing Systems Design steps – Part Six ", I explained the subdivisions: Bonding for Over 250 Volts and Bonding of Piping Systems and Exposed Structural Steel.


  • Usually, the interior columns and beams in any building are connected by riveted or bolted construction joints; these construction joints will not ensure good electrical continuity between the interior columns and beams, so bonding of beams to columns is required to provide long term low resistance joints for electrical continuity throughout the building.

  • Many bonding methods are available to ensure low resistance joints between columns, beams and each other , these bonding methods will vary according to the type of the building as follows:




1- For Exposed steel buildings

  • Bonding columns to beams (Fig.1)


Fig.1

  • Bonding all columns together through their footers by welding a ground bar to the columns which provides future attachment points for other grounding conductors (Fig. 2).


Fig. 2

  • Bonding a flexible conductor to the columns or beams on each side of the expansion joints (Fig. 3).


Fig. 3

  • Bonding The bottom chord of a bar joist (Fig.4).


Fig. 4

  • On exposed steel buildings, the ground bars can be welded directly to the steel column (Fig. 5 and Fig. 6).


Fig. 5



Fig. 6

  • Light duty ground points can be made in office columns (Fig. 7).



Fig. 7








2- For All buildings

  • Bonding Steel columns within the building to the footer with the conductor extending to the main ground grid (Fig. 8 and Fig. 9). The column anchor bolts must be electrically connected to the footer reinforcing bars.


Fig. 8



Fig. 9

  • Cast copper alloy ground plates can be embedded in concrete structures for attachment of future grounding conductors (Fig. 10 and Fig. 11). The plates are provided with drilled and tapped holes for lug attachment.


Fig. 10



Fig. 11

  • When large quantities are required on a job, they are available with a pigtail already attached from the factory to reduce field labor (Fig. 12).


Fig. 12

  • The ground plate also can be exothermically welded directly to a steel column where the column is to be fireproofed (Fig. 13).


Fig. 13

  • In areas where a conductive floor is required, it is bonded to the ground system as shown in (Fig. 14).


Fig. 14

  • In areas where static electricity must be controlled, metal doors and frames must be bonded as shown in (Fig. 15).


Fig. 15

  • Metal handrails should be grounded if there is an accessible ground conductor available, a good reason to use cast copper alloy ground plates embedded in the concrete at frequent intervals. (Fig. 16).



Fig. 16








3- For Multi floor buildings

  • On multi-floor buildings, Steel columns within the building should be bonded to the footer with the conductor extending to the main ground grid conductor which should extend to each floor (Fig. 17).


Fig. 17

  • For accessible ground points at each floor, ground bars provide the ideal solution. They can be bolted to either the wall or the floor or a long bus attached to the wall with insulators and mounting brackets. (Fig. 18).



Fig. 18








4- For Large facilities having multiple buildings with underground utilities

  • At large facilities having multiple buildings with underground utilities, the cable racks in the manholes can be grounded as detailed in (Fig. 19), (Fig. 20) and (Fig.21).


Fig. 19



Fig. 20


Fig. 21







Now, we finish the third grounding system division existing in any building: The building interior bonding as we have five divisions of grounding system in any building which are:





Grounding System Subdivisions

Grounding system in any building can be broken down into several subdivisions:

  1. The building exterior grounds,
  2. The electrical service grounding,
  3. The building interior bonding,
  4. Equipment grounding and bonding,
  5. Lightning protection.






In the next Article, I will explain the forth grounding system division existing in any building: Equipment grounding and bonding. Please, keep following.





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