In Article " Earthing Systems Design steps – Part One ", I indicated the following points:
Earthing Systems Design
Steps
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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:
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In this Article, I explained the Building Exterior Grounds and Today I will explain Other Building’s Earthing System Divisions as follows.
You can preview the following Articles for more info:
In Article " Earthing Systems Design steps – Part Five ", I 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:
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And I explained three subdivisions in this article and today I will continue explaining other subdivisions of The Building Interior Bonding.
4- Bonding for Over 250 Volts
4.1 The bonding requirements for electrical circuits which operate at over 250 volts to ground:
NEC Section 250-97 requires that such circuits be bonded to ensure electrical continuity of metal raceways or cable armors or sheaths that contain any conductor other than service conductors shall be ensured by one or more of the methods specified for services in 250.92(B), except for (B)(1).
4.2 Methods of Bonding for Circuits Over 250 Volts
First case: Where oversized
concentric or eccentric knockouts are present in a box or an enclosure (see fig.1)
The permissible methods which can be used
to achieve the required bonding are:
Notes:
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Fig-1 |
Second case: Where oversized concentric or
eccentric knockouts are not encountered or where they are encountered in a
box or enclosure which has been tested and listed as suitable for bonding
The permissible methods which can be used
to achieve the required bonding are:
Note:
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5- Bonding of Piping Systems and Exposed Structural Steel
5.1 Metal Water Piping
5.1.1 Requirements for
bonding interior metal water piping systems
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Metal Water Piping Bonding |
Notes
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5.2 Other Metal Piping
Requirements for bonding
Other Metal Piping
Any interior piping systems, such as,
domestic well water, or any piping which contains a liquid or a gas, and “may
become energized,” shall be bonded. Once again the permissible bonding
locations are to the service equipment enclosure, the grounding electrode
conductor, the service grounded conductor or the one or more grounding
electrodes that comprise the grounding electrode system.
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General Rule for Metal Piping
Bonding
If the interior metal piping system
contains any electrical devices, such as, solenoids or mechanized valves, the
piping “may become energized” and it should be bonded.
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5.3 Exposed Structural Metal
Requirements for bonding
Exposed Structural Metal
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Bonding of Exposed Structural Metal |
Notes
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In the next Article, I will continue explaining the last Building Interior Bonding Division: Bonding of Interior Metal Columns and Beam. Please, keep following.
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