Parts and terms

Every word the simulator uses, grouped by what kind of thing it is. Most confusion comes from mixing the buckets up — a riser is not a part, and rough-in is not a component.

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1. The path

Every station on the path does one of three jobs: it measures, it protects, or it distributes. Once you know which job a part does, its position in the chain is obvious.

The whole chain. Colour marks the job each station does. Notice there are only three jobs — once you can name a part's job, you know where it sits.

Service drop / service entrance: The conductors running from the utility's pole to your house. "Drop" when it comes overhead, "lateral" when it comes underground. This is the boundary — the utility owns one side, you own the other.
Watthour meter (kWh meter): Measures. Counts the energy you use so the utility can bill you. Owned and sealed by the utility; you don't touch it. It sits before everything of yours, so every kilowatt-hour that enters the house is counted.
Main breaker / main disconnect: Protects. One switch that kills power to the whole house, and trips if the total current exceeds its rating. It also protects the service entrance conductors behind it.
Panelboard (panel, load centre, breaker box): Distributes. Takes the one incoming supply and splits it into many branch circuits, each with its own breaker. Inside are the bus bars — metal strips the breakers clip onto — plus a neutral bus and a ground bus.
Branch circuit: One breaker and the wiring it feeds. This is the unit everything is counted in: "an eight-circuit house" means eight breakers, each running its own set of outlets or lights. Circuit 1 on your schedule is one branch circuit.
Feeder: A run between two panels, rather than from a panel to outlets. It is the same idea as a branch circuit but bigger, because it carries everything downstream of it.
Sub-panel: Distributes, again. A second panelboard fed by a feeder from the main. Used when a part of the building is far from the main panel — a garage, a second floor, a workshop — so you run one big cable instead of a dozen small ones.
Utility box / junction box / octagon box: The enclosure a splice or a device sits in. Every connection must be inside a box — that is what stops a loose splice from starting a fire in a wall. An octagon box is the eight-sided one used at ceiling lighting outlets; a utility box is the rectangular one for switches and outlets.
Convenience outlet (CO): An ordinary wall socket. Called a receptacle or "convenience outlet" on plans; in everyday Philippine speech, a saksakan.
Special purpose outlet (SPO): An outlet dedicated to one appliance — aircon, water heater, range. It gets its own circuit and its own breaker, because sharing would overload the wire.
Lighting outlet: The point a light fixture connects to. Note it means the connection point, not the lamp — this trips people up on plans.
Home run: The stretch of a circuit that goes back to the panel. On a plan it's the arrow with the circuit number, marking where that circuit's cable leaves for the panelboard.
Ground rod / grounding electrode: Protects. A copper-clad rod driven into the earth, connected to the panel by the grounding electrode conductor. It gives fault current and lightning a path into the ground instead of through you.

Every connection lives in a box. That is the rule that stops a loose splice starting a fire inside a wall. The shape tells you the purpose.

Why order matters. Meter before main breaker, main breaker before panel, panel before circuits. Anything upstream of a protective device is unprotected — which is why the service entrance conductors between the meter and the main breaker are kept as short as the code allows.

2. The conductors

Hot goes out, neutral comes back, ground does nothing at all until something breaks. Everything else — traveller, switched leg — is just a hot wire with a job description.

One lamp, one switch. Follow the red: it stops at the switch and leaves as blue. The white never passes through the switch at all, and the green does nothing until there is a fault.

Hot (live, line, phase): Carries voltage from the source. Touching it while grounded is what shocks you. Red or black in Philippine practice. Switching and fuses always belong on the hot side.
Neutral: The return path back to the source. It normally carries the same current as the hot, so it is not safe to treat as dead — it is only near zero volts because it is bonded to earth back at the service. White.
Ground (equipment grounding conductor): Carries no current in normal operation. Its whole job is to give fault current a low-resistance path back so the breaker trips fast. Green, or bare copper.
Switched leg (switch leg, load wire): The hot wire after the switch — live only when the switch is on. Runs from the switch to the fixture.
Traveller: The pair of wires running between two three-way switches. Either one may be live depending on switch positions, which is exactly how three-way switching works.
Common (COM): The odd terminal on a three-way switch — usually a darker screw. The switch connects the common to one traveller or the other. Get the common wrong and the pair behaves erratically instead of failing outright, which is why it's a hard fault to find.
Bonding: Deliberately connecting metal parts together so they sit at the same voltage. Boxes, conduit and fixture bodies are all bonded to ground.
Conduit: The pipe conductors are pulled through — PVC or metal. It protects the wire mechanically and lets you replace it later. Conduit fill is the rule limiting how many conductors may share one pipe, so they can dissipate heat and still be pulled.

The single most important difference between a main panel and a sub-panel. Neutral and ground are joined once, at the service. At a sub-panel the neutral bus floats clear of the enclosure and the ground is its own conductor.

The one that actually hurts people: a switched neutral. If the switch interrupts the neutral instead of the hot, the lamp turns on and off perfectly normally — but the fixture stays live with the switch off. Someone changing a bulb gets shocked. It looks correct and tests correct with a lamp. Only a voltage tester finds it.

3. The numbers

Almost everything traces back to one relationship: amps = watts ÷ volts. Work out the amps, pick a wire that can carry them, then pick a breaker that protects the wire.

Ampacity: How much current a conductor can carry continuously without overheating. It is a property of the wire, and it is the number the breaker is chosen to protect.
The breaker protects the wire, not the appliance: This is the idea that makes the whole table make sense. A 20 A breaker on 3.5 mm² wire is not there to save your aircon — it is there to stop the cable inside your wall from getting hot enough to burn. That is also why an oversized breaker is dangerous while an oversized wire is merely expensive.
mm² and AWG: Two ways of stating conductor size. mm² is the actual cross-sectional area of copper and is what Philippine practice uses; AWG is the American gauge system, where a smaller number means a bigger wire.
Continuous load, and the 125% rule: A load running three hours or more without a break. It must be sized at 125% of its rating — the same thing as keeping the conductor at or below 80% of its ampacity. Lighting and aircon count; a rice cooker does not.
Pole (1P, 2P): How many conductors the breaker interrupts. A two-pole breaker opens both wires at once with a single handle, which is what a 230 V appliance circuit wants.
AT and AF: On Philippine plans, AT is ampere trip — the current at which it trips, the number you actually size. AF is ampere frame — the physical body size the breaker is built in. Several AT ratings share one AF.
Voltage drop: Voltage lost along a long cable run. Ampacity alone can approve a wire that is still too thin over distance, which is why long runs get upsized. It matters far more on low-voltage DC than on 230 V AC. Not yet calculated by the simulator.
Connected load vs demand load: Connected load is everything added up. Demand load is what will realistically run at once — always less, because you don't use every appliance simultaneously. Real service sizing uses demand factors; the simulator uses connected load, which is the conservative direction.

Why the table looks the way it does. Ampacity tracks copper area, so the jump from 2.0 to 14 mm² is a sevenfold increase in metal for less than four times the current — the extra is margin against heat.

mm²	AWG	Ampacity	Usual breaker	Typical use
2.0	14	15 A	15 A	Lighting
3.5	12	20 A	20 A	Outlets, small aircon
5.5	10	30 A	30 A	Aircon, water heater
8.0	8	40 A	40 A	Range, small service
14	6	55 A	50 A	Service entrance

Ampacities for THHN copper at 30 °C ambient. Real installations derate for heat and for bundling — these are the starting figures, not the final answer.

4. The drawings

None of these are hardware. Rough-in is a stage of work; the others are kinds of drawing, each answering a different question about the same house.

Three sheets, three questions, one house. None of them is complete on its own — which is why a permit set carries all three.

Rough-in: The stage before the walls close: conduit, boxes, and wire pulled through them. No devices, no fixtures, no cover plates. Wires are left long and hanging on purpose so there is slack for trim-out. Inspection happens here, while everything is still visible.
Trim-out: The stage after the walls and ceilings are finished: terminate the conductors, install the switches, outlets and fixtures, fit the plates.
Lighting layout: Where. A floor plan showing lighting outlets, switches, and which switch controls which light.
Power layout: Where, again — but for convenience outlets and special purpose outlets. Kept on a separate sheet from lighting so neither becomes unreadable.
Legend: The key to the symbols. Non-negotiable on a real plan: symbols are not fully standardised, so the legend is what makes the drawing mean anything.
Schedule of loads: The numbers. A table, one row per circuit, listing the load, current, conductor, conduit and breaker. It is where the sizing is justified — the drawing shows intent, the schedule shows the arithmetic.
Riser diagram / one-line diagram: How it all connects. A schematic of the whole service, from utility through meter, main breaker and panel to the circuits. Not to scale and not in real positions. Called "riser" because in a multi-storey building the service rises through the floors — the name sticks even in a bungalow.
One-line (single-line): The convention the riser is drawn in: a single line represents a run even when it is two or three conductors, with tick marks giving the count. Drawing every conductor would make the sheet unreadable.
Title block: The bordered strip carrying the project name, what the sheet shows, the scale, the date and the sheet number. It's how a drawing stays identifiable once it's off your screen.

How the sheets fit together. The layouts say where. The riser says how connected. The schedule says how big. Any one alone is incomplete, which is why a permit set includes all three.

5. The solar side

Size everything from consumption, never from panels. Work out the watt-hours you use per day first; every other number follows from it.

The order matters as much as the parts. The inverter goes straight to the battery with its own fuse. Its surge draw is many times what a controller’s load terminals can pass.

Peak sun hours (PSH): Not hours of daylight. It is the day's total solar energy re-expressed as hours at a convenient full-strength 1000 W/m². The Philippines averages roughly 4.5–5.5; design on 4.5, or 4.0 if the rainy season matters to you.
Charge controller: Sits between panel and battery and regulates the charge. The panel's voltage is higher than the battery's and swings all day, which is why it cannot feed a battery directly.
PWM vs MPPT: PWM connects panel to battery and pulls the panel down to battery voltage, wasting the difference. MPPT converts the excess voltage into extra current, so it harvests meaningfully more from the same panel — typically 20–30% more, and the gap widens in cold or cloudy conditions. MPPT costs more and is usually worth it above a few hundred watts.
Depth of discharge (DoD): How much of a battery you may actually use. Lead-acid gives about 50% before its life drops sharply; LiFePO4 gives around 80%. This is why a lithium bank for the same job is often little more than half the nameplate size.
Days of autonomy: How many days the bank should run the house with no sun at all. Two is common; three for somewhere with long wet spells. It multiplies the bank size directly, so it is the most expensive number in the design.
System voltage (12 / 24 / 48 V): The battery bank's voltage. Higher voltage means less current for the same power, so thinner and cheaper cable. Roughly: 12 V below 800 Wp, 24 V to about 2400 Wp, 48 V above that.
Inverter: Turns bank DC into 230 V AC. Sized on the largest load running at once plus about 25%. It connects straight to the battery with its own fuse — never to the charge controller's load terminals, which are typically rated for only 10–20 A.
Surge rating: The brief overload an inverter tolerates at start-up. Motors — fridge, pump, aircon — draw several times their running watts for a moment, so the surge figure matters more than the continuous rating for those loads.
Wp (watt-peak): A panel's output under standard test conditions. Real output is always lower; heat alone costs a noticeable fraction on a hot roof.
Derate: The allowance for everything that loses you energy in practice — heat, dust, cable losses, controller and inverter inefficiency. Around 25% is a common working figure, plus about 10% for the inverter.
Off-grid, grid-tie, hybrid: Off-grid has no utility connection at all. Grid-tie feeds the grid and has no battery, so it goes dead in a blackout. Hybrid has both battery and grid, and can ride through an outage.

DC is less forgiving than the AC wiring elsewhere on this page. Polarity is not optional — there is no neutral to save you. A battery bank can deliver hundreds of amps into a dropped spanner, weld it in place and rupture the battery. And DC arcs do not self-extinguish the way AC ones do, because AC crosses zero volts a hundred times a second and DC never does — so every switch, fuse and breaker on the DC side must be DC-rated. An AC-rated device can fail to break the circuit at all.