Series vs parallel lighting
Take any one lamp out — the whole string dies, because they share one path.
Take any one out — the rest stay lit, because each has its own path to the supply.
In series the lamps share one path, so losing any one stops them all; in parallel each lamp has its own path, so the others carry on. Pull a lamp from either set above and watch the difference play out — it is the whole lesson in one gesture.
How each one behaves
A series circuit is a single loop threaded through every lamp in turn. Current has exactly one route, so every lamp carries the same current, and each takes only a share of the supply voltage. Break the loop anywhere — one dead lamp, one loose connection — and the current has nowhere to go, so all of them go out together.
A parallel circuit gives each lamp its own connection across the supply. Every lamp sees the full voltage and runs at full brightness, and the lamps do not depend on each other. Remove one and its path disappears while the others keep theirs. That independence, and the equal voltage, is why building and branch lighting is wired in parallel.
Questions people ask
Why do old string lights all go out when one bulb fails?
Because they are wired in series — one path through every bulb. Break the path anywhere and current stops everywhere. Remove a lamp from the series string in the diagram and watch all three go dark at once. Modern strings add a shunt in each socket precisely to dodge this.
Why are building lights wired in parallel?
So each fixture sits across the full supply on its own path, independent of the others. One can fail or be switched off without touching the rest, and every fixture gets the same voltage. Pull one lamp in the parallel set and the others stay lit.
Do series lamps share the voltage?
Yes — the supply voltage divides across the lamps in series, so each sees only a share of it and burns dimmer than it would alone. In parallel each lamp gets the whole voltage and runs at full brightness. That difference in what each lamp sees is the heart of it.
Related
- Single-pole switch wiring — one lamp on its own path.
- Ohm's law practice — drill the voltage and current maths behind this.
- All wiring diagrams
Learn one thing a week
Now and then a new diagram, drill, or reference sheet goes up. Leave your email for a short heads-up when it does — no spam, no selling it on, one click to leave.