Design Current and Calculation of the Minimum Required Value of the Cable's Current Carrying Capacity
General
For ring socket circuit with Ιn = 30Α or 32Α
Ring socket circuits otherwise
Grouped circuits not liable to
simultaneous overload
General motor circuits
Star-Delta Motor Circuits
With:
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the design current of the circuit under consideration in Amperes
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the nominal current or current setting of the protective device protecting the circuit against overcurrent in Amperes
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the minimum required value of the cable’s current carrying capacity
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Criteria for type gG fuses - Comply with the IEC Standard requirement I2 ≤ 1.45 Iz:
As per the IEC standard, the condition I2 ≤ 1.45 Iz must be taken into account, where I2 is the fusing (melting level) current, equal to k2 x In (k2 ranges from 1.6 to 1.9) depending on the particular fuse concerned.
In such a case an extra factor k3 = 1.31 for fuses with In < 16A , or k3 = 1.1 for fuses with In ≥ 16A is considered, in order that I2 ≤ 1.45 Iz will be valid if In ≤ Iz/k3.
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Checks
With:
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the design current of the circuit under consideration in Amperes
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the nominal current or current setting of the protective device protecting the circuit against overcurrent in Amperes
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the minimum required value of the cable’s current carrying capacity
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the value of current tabulated in cable tables
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Correction factor for ambient temperature
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Correction factor for thermal insulation
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Correction factor for grouping
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Correction factor for using BS3036
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Correction factor for ground installations
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Correction factor for underground installation depth
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Correction factor for ground soil thermal resistivity
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Correction factor for triple harmonic currents
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Motor starter overload. By default
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