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Wire size
Wire-size guides help you pick conductors that satisfy ampacity and voltage-drop limits without guessing from memory alone.
They support both learning and fast estimating when a takeoff needs defensible wire choices.
Guides in this tag
- What Size Wire and Breaker for an EV Charger?
A 48 A charger needs a 60 A breaker on 6 AWG copper - because 625.41 makes EV charging continuous by rule. Plus the two traps: 6/3 Romex is not enough for 60 A, and a 50 A charger costs more than a 48 A one.
- What Size Wire Do I Need? AWG by Amps, Distance, and Material
How to size wire the way the NEC does: run the ampacity test against Table 310.16, run the voltage drop test against the length, and take whichever answer is larger. Includes an amps-to-AWG chart for copper and aluminum.
- Voltage Drop: How to Calculate It and What the NEC 3% Rule Really Says
How to calculate voltage drop with the circular-mil formula, what the NEC actually says about the 3% and 5% limits (they're informational notes, not requirements), three worked examples, and how to fix a run that fails.
- What Size Wire for a 100 Amp Sub Panel?
The answer depends on whether the feeder carries the whole house. Ordinary subpanel: 3 AWG copper or 1 AWG aluminum from Table 310.16. Whole-dwelling feeder: 4 AWG copper under the 83% rule. Plus ground size, neutral, and the bonding mistake.
- 200 Amp Service Wire Size: Copper vs Aluminum and the 83% Rule
A 200 amp dwelling service takes 2/0 copper or 4/0 aluminum - smaller than the ampacity table suggests, because Table 310.12 permits 83% sizing. Where that allowance applies, the GEC size, and the neutral.
Related resources
- 04 Aug, 2026
What Size Wire and Breaker for an EV Charger?
A 48 A charger needs a 60 A breaker on 6 AWG copper - because 625.41 makes EV charging continuous by rule. Plus the two traps: 6/3 Romex is not enough for 60 A, and a 50 A charger costs more than a 48 A one.
- 03 Aug, 2026
What Size Wire Do I Need? AWG by Amps, Distance, and Material
How to size wire the way the NEC does: run the ampacity test against Table 310.16, run the voltage drop test against the length, and take whichever answer is larger. Includes an amps-to-AWG chart for copper and aluminum.
- 03 Aug, 2026
Voltage Drop: How to Calculate It and What the NEC 3% Rule Really Says
How to calculate voltage drop with the circular-mil formula, what the NEC actually says about the 3% and 5% limits (they're informational notes, not requirements), three worked examples, and how to fix a run that fails.
- 03 Aug, 2026
What Size Wire for a 100 Amp Sub Panel?
The answer depends on whether the feeder carries the whole house. Ordinary subpanel: 3 AWG copper or 1 AWG aluminum from Table 310.16. Whole-dwelling feeder: 4 AWG copper under the 83% rule. Plus ground size, neutral, and the bonding mistake.
- 03 Aug, 2026
200 Amp Service Wire Size: Copper vs Aluminum and the 83% Rule
A 200 amp dwelling service takes 2/0 copper or 4/0 aluminum - smaller than the ampacity table suggests, because Table 310.12 permits 83% sizing. Where that allowance applies, the GEC size, and the neutral.
Frequently asked questions
Common questions about Wire size guides on the TradesQuote blog.
What will I find under Wire size?+
This tag lists 5 published guides tagged or categorized as Wire size. Topics typically include sizing, cost estimating, diagnostics, and practical contractor workflows tied to that subject.
Are these articles a substitute for code or engineered design?+
No. TradesQuote guides explain concepts and estimating shortcuts so you can work faster and communicate clearly. Always follow applicable codes, manufacturer instructions, and professional engineering requirements for the job.
How do these pages relate to TradesQuote tools?+
Many articles link to free HVAC or electrical calculators and to TradesQuote estimating features. Use the guides to understand the topic, then use the tools to produce numbers for proposals and field checks.