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Electrical FAQ

Straight answers to the wiring questions people actually ask, grounded in the NEC tables and formulas our calculators run on. Short, specific, and honest about when to call a licensed electrician.

Wire Gauge & Ampacity

How many amps can 12 AWG handle? How many amps can #10 handle?

Voltage Drop

How much voltage drop is acceptable? When should I worry about voltage drop?

Breakers & Circuits

What is the 125% rule in electrical? What happens if you put a 20 amp breaker on 14 gauge wire?

Conduit Fill

What is the 40% conduit fill rule? How many #12 wires can you put in a 1/2 conduit?

Conduit Bending

How many inches do you deduct for a 90 degree bend? What is the formula for a 90 degree bend?

Panels, Services & Sub Panels

How much does it cost to go from 100amp to 200amp service? What can you run on a 100 amp service? How many breakers can go on a 200 amp panel? Is 2 2 2 4 good for 100 amp service? Should I upgrade my house to 200 amp service? Can you run a 100 amp subpanel off a 200 amp main panel?

Romex, THHN & Aluminum Wire

Is it hard to sell a house with aluminum wiring? Does THHN wire need conduit? Is aluminum wiring still allowed? Why is Romex illegal in Chicago? Is it against code to put Romex in conduit? When not to use Romex?

Extension Cords & 12V Wiring

Do I need a 12 or 14 gauge extension cord?

Generators, EV Charging & Solar

How much does an EV charger installation cost? How big of a generator do I need to run a 2000 sq ft house? Can a normal electrician install an EV charger?

NEC Code & DIY Rules

How do I read the NEC for free? How much would it cost to rewire a 100 year old house? Is the 2026 NEC code book available? Do you have to tear down walls to rewire a house?