110.1 Scope of Article 100
This article covers the general Requirements for electrical installations.
110.2 equipment approvals
Conductors and equipment can be installed only if there are approved by AHJ.
For more understanding of terms “approval”, Please review the following post:
Definitions of identified, listed and approved terms
Conductors and equipment can be installed only if there are approved by AHJ.
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| NEC Article 110.2 |
Definitions of identified, listed and approved terms
110.3 equipment installation
Equipment must be installed in accordance with any instructions included in their listing or labeling requirements otherwise it will be a violation of the code.
NEC Article 110.3
For more understanding of terms “listing and labeling”, please review the following post:
110.4 equipment voltage rating
The voltage rating of electrical equipment shall not be less than the nominal voltage of a circuit to which it is connected.
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| NEC Article 110.4 |
110.5 Conductor Material
Where the conductor material is not specified, the material and the sizes given in this Code shall apply to copper conductors. This means that you must pay attention for using appropriate code values which to be applied in case of using Aluminum conductors especially for tables included in chapter 9.
110.6 Conductor size unit
Conductor sizes are expressed in American Wire Gage (AWG) or in circular mils units.
Conductors up to size 4/0 AWG will be sized in AWG.
Conductors larger than 4/0 AWG are sized in circular mils CM or MCM (MCM=1000CM) or Kcmil (Kcmil=MCM=1000CM.
How to calculate the circular mils size of a conductor?
by using the following Equation:
Circular mils CM = D2 x106
Where D is conductor diameter in inch.
For converting from mm2 to AWG and vice versa use the below table:
AWG TO MM2 CONVERSION TABLE
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AWG
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mm2
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30
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0.05
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28
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0.08
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26
|
0.14
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24
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0.25
|
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22
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0.34
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21
|
0.38
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20
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0.50
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18
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0.75
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17
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1.0
|
|
16
|
1.5
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14
|
2.5
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12
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4
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10
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6
|
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8
|
10
|
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6
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16
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4
|
25
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2
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35
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1
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50
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1/0
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55
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2/0
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70
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3/0
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95
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4/0
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120
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300MCM
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150
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350MCM
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185
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500MCM
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240
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600MCM
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300
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750MCM
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400
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1000MCM
|
500
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You can also use and download the AWG X mm2
Calculator by clicking on the link.
110.9 Interrupting Rating
Equipment intended to interrupt current at fault levels shall have an interrupting rating sufficient for the nominal circuit voltage and the current that is available at the line terminals of the equipment.
You must differentiate between the following terms:
Interrupting Rating(IR): It is the maximum short-circuit current that an overcurrent protective device can safely interrupt under standard test conditions.
Interrupting capacity (IC): is the highest current at rated voltage that a device can interrupt (no fault).
Short circuit current rating (SSCR): The maximum short circuit current that equipment can safely withstand when protected by a specific overcurrent protective device, or for a specified time interval.
Overcurrent protective devices (such as fuses and circuit breakers) should be selected to ensure that the short-circuit current rating of the system components (wire, bus structures, switching, protection and disconnect devices, and distribution equipment) is not exceeded.
in the next topic, we will continue explaining the important code rules in Article 110. please keep following.
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