Philippine Electrical Code (PEC)
Wiring methods, grounding, protection, and installation requirements
1. General Requirements
About the PEC
The Philippine Electrical Code is based on the US National Electrical Code (NEC) and sets minimum requirements for safe electrical installations in the Philippines.
Voltage Classifications
- Low Voltage (LV): Up to 1000V
- Medium Voltage (MV): 1001V to 69kV
- High Voltage (HV): Above 69kV
Standard Service Voltages (Philippines):
- • Single-phase: 230V (phase-to-neutral)
- • Three-phase: 400V (phase-to-phase)
- • Frequency: 60 Hz
Working Space Requirements
| Voltage (to ground) | Min. Clear Distance | Min. Headroom |
|---|---|---|
| 0-150V | 900mm (3 ft) | 2m (6.5 ft) |
| 151-600V | 900mm (3 ft) | 2m (6.5 ft) |
| 601-2500V | 1200mm (4 ft) | 2.4m (8 ft) |
2. Conductor Sizing
Minimum Wire Sizes
- Branch circuits: Minimum 3.5 mm² (12 AWG)
- Lighting circuits: Minimum 2.0 mm² (14 AWG)
- Fixture wires: Minimum 0.75 mm² (18 AWG)
- Service entrance: Minimum 8.0 mm² (8 AWG)
Conductor Ampacity
Ampacity depends on conductor size, insulation type, and installation conditions.
| Size (mm²) | AWG | TW (60°C) | THHN (90°C) |
|---|---|---|---|
| 2.0 | 14 | 15A | 25A |
| 3.5 | 12 | 20A | 30A |
| 5.5 | 10 | 30A | 40A |
| 8.0 | 8 | 40A | 55A |
| 14 | 6 | 55A | 75A |
| 22 | 4 | 70A | 95A |
Correction Factors
Temperature Correction
If ambient temp > 30°C, reduce ampacity
At 40°C: multiply by 0.82 (TW)
At 40°C: multiply by 0.91 (THHN)
Bundling/Conduit Fill
4-6 conductors: multiply by 0.80
7-9 conductors: multiply by 0.70
10-20 conductors: multiply by 0.50
3. Voltage Drop
PEC Voltage Drop Limits
Voltage drop should not exceed 3% for branch circuits, 5% total for feeder + branch.
Recommended Limits
- Branch circuit: Maximum 3%
- Feeder: Maximum 2%
- Total (Feeder + Branch): Maximum 5%
Voltage Drop Calculation
Single-phase:
VD = 2 × I × L × R / 1000
Three-phase:
VD = √3 × I × L × R / 1000
VD = voltage drop (V), I = current (A), L = length (m), R = resistance (Ω/km)
Percentage Voltage Drop
%VD = (VD / Vsource) × 100%
Ensure %VD ≤ 3% for branch, ≤ 5% total
4. Wiring Methods
Conduit Types
| Type | Description | Application |
|---|---|---|
| RSC (Rigid Steel) | Thick-wall steel, threaded | Exposed, hazardous locations |
| IMC (Intermediate) | Medium-wall steel, threaded | Similar to RSC, lighter |
| EMT (Electrical Metallic Tubing) | Thin-wall steel, compression fittings | Indoor dry locations |
| PVC (Rigid Non-metallic) | Plastic conduit | Underground, corrosive areas |
| FMC (Flexible Metal) | Interlocked armor | Final connections to equipment |
Conduit Fill
Maximum Conduit Fill
- 1 conductor: 53% of conduit area
- 2 conductors: 31% of conduit area
- 3+ conductors: 40% of conduit area
Applies to same size conductors; calculate for mixed sizes
Box Fill
Each conductor counts as volume allowance:
- • 14 AWG (2.0 mm²): 32.8 cm³
- • 12 AWG (3.5 mm²): 36.9 cm³
- • 10 AWG (5.5 mm²): 41.0 cm³
Add allowance for devices, clamps, and equipment grounding
5. Grounding and Bonding
Purpose of Grounding
- • Limit voltage from lightning/line surges
- • Stabilize voltage during normal operation
- • Facilitate overcurrent device operation
- • Personnel and equipment safety
Grounding Terminology
Grounded Conductor
Current-carrying conductor intentionally grounded (neutral)
Color: White or gray
Grounding Conductor
Non-current-carrying conductor for fault current
Color: Green or bare
Grounding Electrode System
Types of Grounding Electrodes:
- Ground Rod: Min. 16mm dia, 2.4m long (copper-clad steel)
- Ground Plate: Min. 900 cm², 1.5mm thick (copper)
- Concrete-Encased (Ufer): 6m of #4 AWG in foundation
- Water Pipe: 3m in contact with earth (if metal)
Ground Resistance
Maximum Ground Resistance
- Single electrode: ≤ 25 ohms
- If > 25 ohms: Add supplemental electrode
- Substations/Industrial: ≤ 5 ohms recommended
- Communications: ≤ 5 ohms recommended
Equipment Grounding Conductor (EGC)
| OCPD Rating (A) | Copper EGC (mm²) | Aluminum EGC (mm²) |
|---|---|---|
| 15-20 | 2.0 | 3.5 |
| 30 | 3.5 | 5.5 |
| 60 | 5.5 | 8.0 |
| 100 | 8.0 | 14 |
| 200 | 14 | 22 |
6. Overcurrent Protection
General Rules
- Conductor protection: OCPD rating ≤ conductor ampacity
- Standard ratings: 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000, 5000, 6000 A
Load Calculations
OCPD Rating ≥ 125% × Continuous Load + 100% × Non-continuous Load
Continuous load = operates 3+ hours continuously
Branch Circuit Ratings
| Circuit Rating | Min. Wire Size | Receptacle Rating | Typical Use |
|---|---|---|---|
| 15A | 2.0 mm² | 15A | Lighting |
| 20A | 3.5 mm² | 15A or 20A | General purpose |
| 30A | 5.5 mm² | 30A | Appliances |
Coordination
Protective devices should be coordinated so that the device nearest the fault clears first (selectivity). Typical ratios:
- • Fuses: 2:1 ratio between upstream and downstream
- • Breakers: Follow manufacturer coordination tables
7. Motor Installations
Motor Circuit Components
- Branch circuit conductors: ≥ 125% of motor FLC
- Short-circuit protection: Varies by motor type
- Overload protection: Based on service factor or temp rise
- Disconnecting means: Required within sight of motor
Motor Branch Circuit Protection
Maximum OCPD Rating (Percent of FLC)
| Motor Type | Inverse-Time Breaker | Fuse (Time-Delay) | Inst. Trip Breaker |
|---|---|---|---|
| AC Squirrel Cage | 250% | 175% | 1100% |
| AC Wound Rotor | 150% | 150% | 800% |
| DC Motor | 150% | 150% | 250% |
Motor Overload Protection
- Service Factor ≥ 1.15: Overload trip ≤ 125% × FLC
- Temperature Rise ≤ 40°C: Overload trip ≤ 125% × FLC
- All other motors: Overload trip ≤ 115% × FLC
Multiple Motors
Feeder to multiple motors:
Conductor = 125% × Largest FLC + Sum of other FLCs
OCPD = Largest motor OCPD + Sum of other FLCs
8. Special Installations
Transformer Installation
Primary Protection (Overcurrent)
- Impedance ≤ 6%: Max 125% of primary current (use next size up)
- Impedance > 6% to 10%: Max 167% of primary current
- Secondary protection: Required if primary > 125%
Emergency Systems
- • Transfer within 10 seconds of power failure
- • Separate wiring from normal circuits
- • Circuit breakers must be labeled/identified
- • Battery backup or generator required
GFCI Requirements
Ground-Fault Circuit Interrupter (5mA trip) required for:
- • Bathrooms - all receptacles
- • Kitchens - within 1.8m of sink
- • Garages and accessory buildings
- • Outdoors - all receptacles
- • Laundry areas
- • Unfinished basements
- • Swimming pool areas
Hazardous Locations
Class I (Flammable Gases/Vapors)
Division 1: Normal operation
Division 2: Abnormal conditions only
Class II (Combustible Dust)
Division 1: Normal operation
Division 2: Abnormal conditions only
Require explosion-proof or intrinsically safe equipment
Solar PV Systems
- • Inverter output: Standard AC requirements
- • DC circuits: Sized for 125% of Isc
- • Rapid shutdown required for rooftop systems
- • Disconnect required on both DC and AC sides
- • Ground-fault protection for systems > 50V
Key Takeaways for EE Board Exam
Must-Know Values
- ✓ Min. branch circuit: 3.5 mm² (12 AWG)
- ✓ VD: 3% branch, 5% total
- ✓ Conduit fill: 40% for 3+ conductors
- ✓ Ground resistance: ≤ 25Ω single rod
- ✓ Continuous load: 125%
- ✓ Motor conductor: 125% FLC
- ✓ Induction motor OCPD: 250% max
Critical Rules
- ✓ Grounded = White/Gray (neutral)
- ✓ Grounding = Green/Bare (safety)
- ✓ GFCI trips at 5mA
- ✓ Working space: min 900mm front
- ✓ Transformer primary: max 125%
- ✓ Emergency: 10 sec transfer
- ✓ Service voltage: 230V 1φ, 400V 3φ