Isolation of the neutral conductor: Difference between revisions
From Electrical Installation Guide
(Removed extra space between new Note point and Image) |
*>CleanUpAuto (clean-up 2016 - imported revision step 20) |
||
| Line 3: | Line 3: | ||
[[File:PictoChap7d.jpg|none]] | [[File:PictoChap7d.jpg|none]] | ||
(see | (see {{FigRef|G64}})<br>It is considered to be the good practice that every circuit be provided with the means for its isolation. | ||
{| class="wikitable" | |||
{| class="wikitable | |||
|- | |- | ||
! width="15%" | | ! width="15%" | | ||
| Line 43: | Line 39: | ||
| Three-phase<br>four wires<br>Sn < Sp | | Three-phase<br>four wires<br>Sn < Sp | ||
| [[File:FigG64g.jpg|none]] | | [[File:FigG64g.jpg|none]] | ||
| | | | ||
| [[File:FigG64g.jpg|none]] | | [[File:FigG64g.jpg|none]] | ||
Revision as of 15:28, 25 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  |
 |
|
 (B) or |
| Single-phase (Phase-Phase) |
 (A) or  |
|
(A) or |
|
| Three-phase four wires Sn ≥ Sph |
 |
 |
|
 (B) |
| Three-phase four wires Sn < Sp |
|
|
(B) |
(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.
Fig. G64: The various situations in which the neutral conductor may appear
(1) In some coutries the rules applied for TN-S are the same than the rules for TN-C
