100A Aluminum Subpanel Feeder at 150 Feet
Long aluminum feeders trade a larger size for a lower metal price. The comparison still offers the copper size at the same distance.
Formula SSC-2026.1
K method · SSC-2026.1
Minimum size
1/0 AWG · 53.5 mm²
Single conductor set
Voltage drop
6.02 V
2.51% · end 234.0 V
Power loss
602 W
I²R at the operating current
Required ampacity
100.0 A
Each conductor 120 A
Material estimate
$1,564.50
3 conductors + EMT
Conductor weight
54.9 lb
24.9 kg · approximate insulated weight
Circle diameters track circular mils. The drawing is a schematic, not a conduit-fill layout.
| Item | Net | Waste | Order | Unit price | Line total |
|---|---|---|---|---|---|
| aluminum 1/0 AWG · 53.5 mm² | 150 ft one way | cuts excluded | 3 conductors | USD | $1,287.00 |
| EMT conduit | 150 ft | — | 150 ft | USD | $277.50 |
| Material | Minimum size | mm² | Drop | End voltage | Loss |
|---|---|---|---|---|---|
| aluminum | 1/0 AWG · 53.5 mm² | 53.5 | 2.51% | 234.0 V | 602 W |
| copper | 2 AWG · 33.6 mm² | 33.6 | 2.43% | 234.2 V | 583 W |
| Distance | Minimum size | Drop | Percent | End voltage |
|---|---|---|---|---|
| 125 ft | 1 AWG · 42.4 mm² | 6.33 V | 2.64% | 233.7 V |
| 150 ft | 1/0 AWG · 53.5 mm² | 6.02 V | 2.51% | 234.0 V |
| 175 ft | 1/0 AWG · 53.5 mm² | 7.03 V | 2.93% | 233.0 V |
Show the deterministic formula
Single phase: Vdrop = 2 × K × I × D / cmil. Three phase: Vdrop = 1.732 × K × I × D / cmil. K is 12.9 for copper and 21.2 for aluminum. D is one-way feet.
Percent drop = Vdrop ÷ source voltage × 100. Green is 3% or less, amber is 3 to 5%, and red is over 5%. Power loss is I²R on the current-carrying conductors.
The smallest conductor that meets both the ampacity (125% when continuous) and the drop limit is selected. Ampacity does not include bundling or temperature correction.
Contractor sign-off
Project: 100A Aluminum Subpanel Feeder at 150 Feet
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This sheet is an estimate for ordering and layout discussion. It is not a sealed design. Confirm the quantities with a licensed local professional and the authority having jurisdiction before you buy or build.
Engineering notes
Long aluminum feeders trade a larger size for a lower metal price. The comparison still offers the copper size at the same distance. The run is 150 ft one way at 100 A on 1ph-240. K is 12.9 for copper and 21.2 for aluminum. Ambient temperature, bundling, and rooftop adders are not applied.
Code reference
NEC 210.19(A) and 215.2(A) informational notes recommend 3 percent on a branch circuit and 5 percent total with the feeder. Ampacity follows the 75°C column of Table 310.16 plus the small-conductor limits. Confirm the adopted edition.
Field questions
- What current is used for the 100 A voltage drop?
- Both the drop and the ampacity check use the entered amps, because this preset is not marked continuous.
- Does this replace the equipment installation manual?
- No. The nameplate, the breaker, and the adopted NEC edition still control. This page is the K-method size and the percent drop.
- Can I switch copper and aluminum?
- Yes. The conductor control and the comparison table both recompute size, drop, and the planning cost.
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