Distribution network design
The key idea
A useful distribution design connects the intended customers through routes that satisfy electrical, service and physical constraints. A short line on a map is only one part of that decision.
Follow the connection
A small LV network starts at an LV source or a transformer secondary. A feeder carries power along the settlement. Poles support the route and provide connection points. Service drops connect the feeder to individual customers.
For a larger area, an MV backbone can supply several transformers. Each transformer supplies an LV zone. The extra voltage level can reduce the distance that high current travels at LV, but it also adds equipment, cost and operating requirements.
Do not confuse these levels. A service drop is not a main feeder, and a transformer zone is not a claim that all its customers reach their independent peaks at the same time.
Try two source alternatives
The diagram uses six invented customers on three trunk poles. It compares an edge source with a centre source. A spacing control selects one of three precomputed geometries.
First, move the source to the centre. The trunk becomes shorter. Then increase settlement spacing. Some customer services exceed the assumed 50 m reach even though their trunk pole remains connected.
- Trunk route
- 360 m
- Services in reach
- 4 / 6
- Trunk drop screen
- 1.84%
C5, C6 exceed the 50 m service reach. Moving the source changes the trunk; these service lengths do not change.
Read the values and assumptions
| Customer | Trunk path (m) | Service (m) | Connection |
|---|---|---|---|
| C1 | 120 | 20 | Connected |
| C2 | 120 | 20 | Connected |
| C3 | 240 | 40 | Connected |
| C4 | 240 | 40 | Connected |
| C5 | 360 | 60 | Out of reach |
| C6 | 360 | 60 | Out of reach |
Model note · Six precomputed teaching geometries: two source positions at three settlement spacings. Six customers, 1.5 kW each; three trunk poles; 50 m service-reach limit. The voltage screen conservatively places all 9 kW at the farthest trunk pole and omits service and transformer impedance. It is a geometry lesson, not an optimized route, site approval or solved feeder. Dashed services exceed the assumed reach and are not counted as served.
Dashed connections are proposed services that exceed the teaching limit; they are not counted as served. Moving the source changes the trunk path, but it does not move a customer or its local service pole. Fixing that service problem needs a different connection or more route infrastructure.
The selected source is a separate alternative. Neither choice silently rewrites the other’s geometry.
What a layout must show
| Question | Evidence needed |
|---|---|
| Which customers are served? | A connected path from the source through the route to each customer. |
| Can a service reach? | Its actual route length and the chosen conductor and service limit. |
| Can the feeder supply the load? | A consistent demand basis, conductor ratings and electrical checks. |
| Can the route be built? | Survey, access, clearances, land rights and applicable construction evidence. |
| What does it cost? | Quantities, pricing basis, dated rates and explicit unpriced items. |
The model’s geometry cannot grant land access. A source near the load centre may reduce electrical distance and still be unsuitable because of ownership, drainage, access or plant footprint.
The math, if you want itOptional — the page reads completely without it
At base spacing the poles sit 120, 240 and 360 m along the settlement. The trunk length is the span from the source to the farthest pole:
trunk length, edge source
Ledge = 360 · s
trunk length, centre source
Lcentre = 240 · s
where s is the spacing multiplier. The longest source-to-pole path falls from 360 m to 120 m when the source moves to the centre.
a service is counted only if it reaches
served ⇔ Lservice ≤ 50 m
Service lengths are 20, 40 and 60 m, two customers each, so four of six are in reach at base spacing. At double spacing they become 40, 80 and 120 m; only two are in reach.
The displayed voltage screen puts all 9 kW at the farthest trunk pole. This is a conservative concentration of the specified load for the simple trunk equation, not a solved multi-load network. Service and transformer drops are omitted, so it is not an end-to-end voltage guarantee.
Review the demand basis
A feeder carries its downstream coincident demand. Adding independent high-percentile peaks from different groups can create a state that does not represent one shared operating case.
Phasor’s current consumer-mix network method can use the same saved declaration as plant demand. Check the method and percentile shown by the run. Historical designs can retain a different RUS basis.
See it in Phasor
Set the brief, source and route constraints. Inspect service reach, unserved structures, electrical findings and assumed costs. Commit the chosen proposal to create electrical model elements and read the separate PF3 cross-check.
Continue
Compare conductor size and network cost, or revisit the plant/network boundary.