Protection against electrical fire risks - synthesis
From Electrical Installation Guide
Conclusion
In addition to protection against electric shock, protection against fire is another main target of a proper design of electrical installation. The minimum requirement is the coordination between overcurrent protective device and conductor permanent and short-time withstand. (See Chapter Sizing and protection of conductors ). But other protective measures are recommended to reduce the risk of fire due to electrical installation.
- For main circuits and distribution circuits, more sensitive earth fault detection than the one necessary for protection against electric shock is recommended.
- For terminal circuits where mechanical withstand of conductor is lower, where the number of connection is higher, where portable equipment can be supplied, in addition to RCD, Arc fault detection device is recommended.
The table below tries to position the different types of current-based protections required or recommended for low voltage installations.
| Protection against electric shock | Protection against thermal effect / Fire | Protection against overcurrent
(IEC 60364-4-43) | |||||
|---|---|---|---|---|---|---|---|
| BE2 location[a] | Other location | ||||||
| Earthing system | Basic protection | Automatic disconnection | Additional protection | Terminal Circuit | Distribution Circuit | ||
| TNC | Insulation of live part / Barriers enclosure | OCPD | NA | NA | NA | RS GFP[c] | OCPD (overload and short-circuit) |
| TNS | OCPD/RCD | RCD 30mA | 300mA RCD AFDD |
AFDD[b] | RCD[b] | ||
| TT | RCD | RCD 30mA | AFDD[b] | RCD[b] | |||
| IT | OCPD/RCD | RCD 30mA | AFDD[b] | RCD[b] | |||
Fig. F96 – Standard voltages between 100 V and 1000 V (IEC 60038 Edition 7.0 2009-06)
