Isolation of the neutral conductor: Difference between revisions
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{{Menu_Sizing_and_protection_of_conductors}} | {{Menu_Sizing_and_protection_of_conductors}} | ||
[[File: | [[File:DB422336.svg]] | ||
{| | (see {{FigRef|G64}}) | ||
It is considered to be the good practice that every circuit be provided with the means for its isolation. | |||
{{TableStart|Tab1222|5col}} | |||
|- | |- | ||
! | ! | ||
! TT | ! TT | ||
! | ! TN-C | ||
! | ! TN-S | ||
! IT | ! IT | ||
|- | |- | ||
| Single-phase | | Single-phase | ||
| [[File: | (Phase-Neutral) | ||
| [[File: | | [[File:DB422337.svg]] | ||
'''or''' <br> | |||
| [[File: | [[File:DB422337.svg]] | ||
| [[File:DB422338.svg]] | |||
| [[File: | | [[File:DB422337.svg]] | ||
| [[File:DB422339.svg]] | |||
'''or''' <br> | |||
[[File:DB422337.svg]] {{TabRef|Tab1222|b}} | |||
|- | |- | ||
| Single-phase | | Single-phase | ||
| [[File: | (Phase-Phase) | ||
| [[File: | | [[File:DB422344.svg]]{{TabRef|Tab1222|a}} | ||
'''or''' <br> | |||
| [[File: | [[File:DB422345.svg]] | ||
| [[File: | | [[File:DB422345.svg]] | ||
| [[File:DB422344.svg]]{{TabRef|Tab1222|a}} | |||
'''or''' <br> | |||
[[File:DB422345.svg]] | |||
| [[File:DB422345.svg]] | |||
|- | |- | ||
| Three-phase | | Three-phase four wires | ||
| [[File: | Sn ≥ Sph | ||
| [[File:DB422341.svg]] | |||
| [[File: | | [[File:DB422342.svg]] | ||
| [[File:DB422341.svg]]{{TabRef|Tab1222|c}} | |||
| [[File: | | [[File:DB422343.svg]]{{TabRef|Tab1222|b}} | ||
'''or''' <br> | |||
| [[File: | [[File:DB422341.svg]] | ||
|- | |- | ||
| Three-phase | | Three-phase four wires Sn < Sph | ||
| [[File: | | [[File:DB422343.svg]] | ||
| | | | ||
| [[File: | | [[File:DB422343.svg]] | ||
| [[File:DB422343.svg]]{{TabRef|Tab1222|b}} | |||
| [[File: | '''or'''<br> | ||
| | [[File:DB422341.svg]] | ||
|- | |||
{{TableEnd|Tab1222|G64|The various situations in which the neutral conductor may appear | |||
|a| Authorized for TT or TN-S systems if a RCD is installed at the origin of the circuit or upstream of it, and if no artificial neutral is <br> distributed downstream of its location | |||
|b| The neutral overcurrent protection is not necessary: | |||
|| - If the neutral conductor is protected against short-circuits by a device placed upstream, or, | |||
|| - If the circuit is protected by a RCD which sensitivity is less than 15% of the neutral admissible current. | |||
|c| In some coutries the rules applied for TN-S are the same than the rules for TN-C }} | |||
[[ru:Изоляция нейтрального провода]] | [[ru:Изоляция нейтрального провода]] | ||
[[zh:中性线的隔离]] | [[zh:中性线的隔离]] | ||
Revision as of 00:40, 29 November 2016
(see Fig. G64)
It is considered to be the good practice that every circuit be provided with the means for its isolation.
| TT | TN-C | TN-S | IT | |
|---|---|---|---|---|
| Single-phase
(Phase-Neutral) |
or |
|
|
or |
| Single-phase
(Phase-Phase) |
 [a]
or |
|
[a]
or |
|
| Three-phase four wires
Sn ≥ Sph |
|
|
[c]
|
 [b]
or |
| Three-phase four wires Sn < Sph |
|
|
[b]
or |
[a] Authorized for TT or TN-S systems if a RCD is installed at the origin of the circuit or upstream of it, and if no artificial neutral is
distributed downstream of its location
[b] The neutral overcurrent protection is not necessary:
- If the neutral conductor is protected against short-circuits by a device placed upstream, or,
- If the circuit is protected by a RCD which sensitivity is less than 15% of the neutral admissible current.
[c] In some coutries the rules applied for TN-S are the same than the rules for TN-C
Fig. G64 – The various situations in which the neutral conductor may appear
