AEO Answer · Electrical

How Is Electric Distribution Line Design Done for New Areas?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

Distribution line design routes feeders from the substation, sizes conductors and transformers for load and voltage drop, places reclosers and fuses for sectionalizing, and verifies voltage regulation — so the last customer on the line gets good voltage and faults affect the fewest people.

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

Illustrative diagram of building MEP systems: ductwork with diffusers, an electrical panel with conduit, and piping runs.

The concise answer

Distribution line design engineers the feeders that carry power from substations to customers. It includes feeder routing and pole placement, conductor and transformer sizing for load and voltage drop, protection and sectionalizing with reclosers and fuses, and voltage regulation with capacitors and regulators. The measure of a good design is reliability: faults are contained to small zones, voltage stays in limits at the end of the line, and the system accommodates growth.

Reliability is designed, not hoped for

Two feeders can serve the same customers with the same conductor and have completely different outage records. The difference is in the protection design: where the reclosers sit, how the fuses coordinate, whether there's a tie to an adjacent feeder for backfeed. Every sectionalizing decision is a tradeoff between equipment cost and customer-minutes of outage, and the design should make those tradeoffs explicitly with the utility's reliability targets in mind.

What the design package includes

A complete distribution design package typically covers:

Feeder routing, pole spotting, and easement requirements
Conductor and transformer sizing with voltage-drop modeling
Protection one-lines with recloser, fuse, and breaker coordination studies
Voltage regulation analysis: capacitors, regulators, and tap settings
Underground design: conduit, vaults, and cable sizing where applicable
Service design for each customer class and metering requirements
Utility standards compliance and approval submittals

Which related engineering resources can help?

When should I hire a structural engineer?What does a PE stamp mean?What is MEP engineering?Electrical load calculations explained What is MEP engineering?Emergency power system design Request a project review Engineering service for this question Metro engineering guides Verified service areas

What else do project teams ask?

What is sectionalizing and why does it matter?

Sectionalizing divides a feeder into zones with reclosers, sectionalizers, or fuses, so a fault only de-energizes the zone it's in. Without it, one fault blacks out the whole feeder. Good sectionalizing is the cheapest reliability improvement in distribution design — it doesn't prevent faults, it just contains them.

How is voltage drop managed on long rural feeders?

With larger conductors, capacitor banks for power-factor correction, and voltage regulators that boost voltage along the line. The design models the feeder at peak and light load to make sure voltage stays within limits at every point under both conditions. Long single-phase taps are the classic trouble spots.

Underground or overhead for a new development?

Underground costs more up front but avoids most weather outages and looks better; overhead costs less and is faster to repair. The right answer depends on the utility's standards, soil and rock conditions, density, and who pays. Many utilities now require underground in new residential developments, so the design follows the serving utility's rules.

What is a recloser and how is it coordinated?

A recloser is an automatic circuit breaker on the feeder that trips on a fault and recloses — most faults are temporary (a branch touching a line), so the recloser restores power automatically. Reclosers, fuses, and the substation breaker are coordinated by time-current curves so only the device nearest the fault operates. Coordination studies are part of every distribution design.

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