100 amp copper dwelling service
Common copper planning lookup.
4 AWG copper dwelling serviceCommon 100 amp conductor100 amp service wire size
100 Amp Service Wire Size
A common 100 amp dwelling service planning lookup is 4 AWG copper or 2 AWG aluminum, but service rules differ from ordinary branch circuits.
Inputs
Results
Immediate estimateCommon 100 amp conductor4 AWG copper dwelling serviceLimited U.S. dwelling service planning lookup; service conductors have rules that differ from ordinary branch circuits.
Circuit or service rating100 A
MaterialCopper
Run length75 ft
Voltage dropNot estimated
Acknowledge the limitations before relying on this as a planning lookup.
Electrical sizing depends on the adopted NEC edition, terminal temperature ratings, insulation type, conductor material, conduit fill, derating, grounding, equipment labels, and local inspection requirements.
Diagram
100 amp service
A dwelling service rating and conductor material select a limited planning row.
- 100 A service
- Material
- Run length
How this calculator works
Select conductor material and run length for a cautious 100 amp dwelling service planning lookup.
Service scope
The page is aimed at U.S. dwelling service planning, not ordinary 100 amp branch-circuit sizing.
Length flag
Longer runs are flagged because service laterals and feeders may need voltage-drop review.
Utility caution
Service conductors can be affected by utility requirements, meter/main equipment, load calculations, and local amendments.
Lookup
match amp rating and conductor material to a common residential planning rowLength flag
flag one-way runs over 100 ft for voltage-drop reviewAssumptions
- Lookup scope: Limited U.S. dwelling service planning lookup; service conductors have rules that differ from ordinary branch circuits.
- Not checked: Voltage drop, grounding conductor size, neutral load, service load calculation, conduit fill, ambient temperature correction, bundling, and equipment-specific requirements.
Worked examples
Long aluminum run
Shows voltage-drop caution.
2 AWG aluminum dwelling serviceCommon 100 amp conductorFAQ
Is this the same as a 100 amp subpanel feeder?
No. Dwelling service conductor rules and feeder rules can differ.
Does this calculate service load?
No. Service load calculation is separate.
Can the utility require something different?
Yes. Utility service guides and local inspection rules can control details.
Sources and review
- National Electrical Code, NFPA. Accessed 2026-07-16.
- Calculators, Southwire. Accessed 2026-07-20.
Reviewed 2026-07-20. Planning estimates only; confirm project-specific requirements.