AWG para mm2 em queda de tensão: guia NEC e IEC com exemplos

Converter AWG para mm2 ajuda no orçamento e na conversa técnica, mas não aprova a instalação. Queda de tensão segue resistência; ampacidade segue norma e instalação.

Resumo

AWG to mm2 is a comparison step; resistance decides voltage drop.
10 AWG is 5.26 mm2; 6 mm2 is slightly larger.
Keep NEC ampacity and IEC installation checks separate.
Use copper and aluminum resistance tables separately.

AWG é uma escala norte-americana. mm2 é área de seção do condutor. Queda de tensão é a perda causada pela impedância do cabo sob carga.

Em NEC, confira 110.14(C), 310.16 e os alvos 3%/5% em 210.19 e 215.2. Em IEC, use IEC 60364-5-52 e a norma local. AWG and IEC references help keep the terminology clear.

For a 120 V circuit, a 0.6 ohm per 1000 ft difference can move a 16 A load from acceptable to over the 3% target.
— Hommer Zhao, Technical Director

Comparação AWG e métrica

Um circuito 120 V, 16 A, 95 ft de ida cai cerca de 4,2% com 12 AWG e 2,7% com 10 AWG. Em métrico, compare 4 mm2 e 6 mm2.

AWG/kcmil	Area	Metric size	Voltage-drop note	Use note
14 AWG	2.08 mm2	2.5 mm2	120 V / 16 A / 100 ft: about 4.2%	Small circuits
12 AWG	3.31 mm2	4 mm2	120 V / 16 A / 100 ft: about 3.3%	Common branch start
10 AWG	5.26 mm2	6 mm2	120 V / 16 A / 100 ft: about 2.1%	Long 20 A runs
8 AWG	8.37 mm2	10 mm2	230 V / 20 A / 50 m: compare datasheet	Equipment circuits
6 AWG	13.3 mm2	16 mm2	400 V / 63 A feeders: check 3-phase	Feeder candidate
4 AWG	21.2 mm2	25 mm2	Use copper/aluminum resistance table	Long feeders

On mixed-standard jobs, document voltage drop by resistance first and ampacity by the legal installation method second.
— Hommer Zhao, Technical Director

Fluxo da calculadora

Cobre e alumínio não se comparam só pela área. Alumínio tem resistência maior e deve ser calculado com tabela própria.

Use the wire size calculator, the wire resistance calculator, and the IEC cable sizing guide together.

When aluminum is proposed, ask for the resistance value before the area; voltage drop follows ohms.
— Hommer Zhao, Technical Director

Perguntas frequentes

Is 10 AWG the same as 6 mm2 cable?

Not exactly. 10 AWG copper is about 5.26 mm2, while a 6 mm2 metric conductor is larger. For voltage drop, the 6 mm2 cable has lower resistance, but ampacity still depends on NEC 310.16 or IEC 60364 installation conditions.

Can I use mm2 area directly in a voltage drop calculator?

Yes if the calculator accepts metric cable area or conductor resistance. For this site, choose the nearest AWG/kcmil size or use the wire resistance calculator to compare ohms per 1000 ft against ohms per kilometer before sizing.

Which voltage drop target should I use with mixed NEC and IEC projects?

Use the project specification first. In NEC work, the common design target is 3% for a branch circuit and 5% combined feeder plus branch circuit. IEC 60364-5-52 commonly evaluates final circuits and distribution circuits by the allowed voltage drop in the national implementation.

Does a larger metric cable automatically pass NEC ampacity?

No. NEC ampacity depends on conductor material, insulation temperature, terminal temperature under NEC 110.14(C), ambient correction, and adjustment factors. A 16 mm2 cable may look larger than 6 AWG by area, but the listed cable type and termination rating still control.

How close is 2.5 mm2 to 14 AWG?

2.5 mm2 is about 14% larger in copper area than 14 AWG, which is 2.08 mm2. That helps voltage drop, but it does not make the cable a substitute for a North American listed 15 A branch-circuit wiring method unless the installation rules permit it.

Should I convert aluminum cable by area or resistance?

Use resistance for voltage drop. Aluminum has about 61% of copper conductivity, so the same mm2 area drops more voltage. For example, 25 mm2 aluminum behaves closer to a much smaller copper conductor for voltage drop than its area alone suggests.

Antes de aprovar substituição, compare corrente, comprimento, material e AWG/mm2 na calculadora.

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