Fire alarm cabling lookup
Look up cable and circuit rules for fire alarm systems.
Inputs
Worked example with the default inputs. The live calculator replaces it when the page loads.
- Circuit type
- Detector or manual call point circuit
- Cores in the cable
- 2
Minimum conductor size
0.75mm²
- Stranded conductor required
- Yes
- Insulation resistance above
- 5MΩ
- Fire rating
- Not set by this clause
- Clause
- 402.1
This result is a design aid. Verify it against the current standard.
Calculation steps
- Clause that applies402.1NZS 4512:2010 Cl 402.2
- Cores in the cable2NZS 4512:2010 Cl 402.1
- Minimum conductor size0.75mm²NZS 4512:2010 Cl 402.1
- Stranded conductor requiredYesNZS 4512:2010 Cl 402.1
- Stranding applies below1mm²NZS 4512:2010 Cl 402.1
- Insulation resistance above5MΩNZS 4512:2010 Cl 402.2
- Fire ratingNot set by this clauseNZS 4512:2010 Cl 402.2
Questions
Each answer describes what this tool calculates. The result is a design aid. Verify against the current standard.
What size cable does a fire alarm circuit need?
NZS 4512:2010 Clause 402.1 gives 0.75 mm² per conductor for two-core cable and 0.5 mm² per conductor where the cable has more than two cores. AmpSize also reports the 1 mm² stranding threshold of the same clause. Read Clause 402.1 for the cable types and the protection it accepts.
Which fire alarm circuits need fire-rated cable?
AmpSize reports two cases. Clause 402.2(m) gives 15 min integrity to AS/NZS 3013 Classification WS11 for a transmission circuit. Clause 402.2(r) gives WS51W for staged evacuation cabling. Read both clauses in full, because each carries conditions this tool does not check.
Does the fire alarm need its own supply circuit?
Yes. Clause 402.2(f) calls for a separate subcircuit and a permanent label. AmpSize prints the label text the clause gives, FIRE ALARM. Read Clause 402.2(f) for where the subcircuit starts and where the label belongs.
What insulation resistance is expected?
Clause 402.2(j) sets the criterion above 5 MΩ, and AmpSize reports that figure. Clause 402.2(i) and Clause 402.2(k) carry the earthing and the separation rules for the same wiring. Read all three before you record a test result.
Does this tool confirm that an installation complies?
No. AmpSize reports the figures of NZS 4512:2010 Clauses 402.1 and 402.2 for the circuit you pick. It is a pointer, not a ruling. A fire alarm installation is checked against the whole standard and against the wiring rules.