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Electrical Reference Tables & Control Symbols
This page provides quick-reference tables and diagrams for electricians and technicians. Use it to check wire sizes, ampacity, protection devices, voltage drop, and common control circuit symbols.
Wire Gauge / Wire Size (Ampacity)
Brazil (mm²)
Conductor Size (mm²) | Ampacity (A) | Typical Use |
|---|---|---|
2.08 mm² | ~15 A | Lighting, small outlets |
3.31 mm² | ~20 A | Outlets, appliances |
5.26 mm² | ~25–30 A | Water heaters, A/C |
8.37 mm² | ~32–36 A | Motors, ovens |
13.3 mm² | ~50 A | Large heaters, feeders |
21.1 mm² | ~65 A | Panels, heavy loads |
USA(mm²)
AWG | mm² | Ampacity (A) | Typical Use |
|---|---|---|---|
4 AWG | 21.1 mm² | 70 A | Panels, heavy loads |
6 AWG | 13.3 mm² | 55 A | Large heaters, feeders |
8 AWG | 8.37 mm² | 40 A | Motors, ovens |
10 AWG | 5.26 mm² | 30 A | Water heaters, A/C |
12 AWG | 3.31 mm² | 20 A | Outlets, appliances |
14 AWG | 2.08 mm² | 15 A | Lighting, small outlets |
⚠️ Always check local electrical codes (NEC, IEC, ABNT) and adjust for temperature, insulation type, and installation conditions.
Voltage Drop (Single-Phase Copper, 120 V, 2% Drop)
AWG | Distance (ft) | Max Current (A) |
|---|---|---|
14 AWG | 200 ft | 12 A |
12 AWG | 150 ft | 16 A |
10 AWG | 100 ft | 24 A |
8 AWG | 75 ft | 32 A |
6 AWG | 50 ft | 40 A |
Recommended Breakers / Fuses (Guide)
Load (A) | Breaker/Fuse Size | Recommended Wire |
|---|---|---|
50 A | 50 A breaker/fuse | 6 AWG / 10 mm²+ |
40 A | 40 A breaker/fuse | 8 AWG / 6–10 mm² |
30 A | 30 A breaker/fuse | 10 AWG / 4–6 mm² |
20 A | 20 A breaker/fuse | 12 AWG / 2.5–4 mm² |
15 A | 15 A breaker/fuse | 14 AWG / 1.5–2.5 mm² |
💡 Keep total voltage drop under 3% for efficiency
Basic Control Circuit Symbols
Symbol | Meaning / Device |
|---|---|
⌂ (Controller) | Digital/PID controller input |
🔺 (Heater/Load) | Resistive load (heater) |
⧖ (Overload Relay) | Protects motor/heater from overload |
─┤├─ (Auxiliary Contact) | Used for interlocking/feedback |
▭▭ (Contactor Coil) | Energizes to close/open main contacts |
⏼ (NC Push Button) | Normally Closed Push Button (Stop) |
⏻ (NO Push Button) | Normally Open Push Button (Start) |
💡 Technical Tip: In PID systems, use short cycle times (1–2s with SSRs, 10–20s with contactors) for optimal stability and equipment life.
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