WireGaugeCalc 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? Which is thicker, 12 or 14 gauge wire? Is it okay to mix 12 and 14 gauge wire? How many amps will 20 gauge wire carry? What is bigger, 14 or 16 gauge wire? Can I mix 16 and 14 gauge wire? Should I wire my house with 12/2 or 14/2? How many amps can I run on a 14 gauge wire? Can 8 gauge wire handle 100 amps? How many amps can 3 AWG wire carry? Which is bigger, 2 AWG or 3 AWG? What are the sizes of wire? What does a wire gauge tell you?
Voltage Drop
How much voltage drop is acceptable? When should I worry about voltage drop? What is voltage drop? What is the most common cause of voltage drop? What is the 3% voltage drop rule? What is the voltage drop per 100 ft? What size wire do I need to carry 100 amps 100 feet? How far can you run a 12/2 wire on a 20 amp circuit?
Breakers & Circuits
What is the 125% rule in electrical? What happens if you put a 20 amp breaker on 14 gauge wire? Can I use 12 AWG for a 20-amp breaker? Is a 30 amp 220 breaker 30 amps on each leg? Is a 20 amp breaker 120 or 240? What size wire do I need for 30 amp 220v? How do I know what size circuit breaker I need? What is the 80% rule for electrical?
Grounding
Conduit Fill
What is the 40% conduit fill rule? How many #12 wires can you put in a 1/2 conduit? How many 12 gauge wires can I run in 1 inch conduit? Will 12/2 fit in 3/4 conduit? What is the fill for 3/4 PVC conduit? What are common mistakes in conduit fill calculations? Do you count neutrals and grounds in conduit fill calculations?
Conduit Bending
Box Fill & Junction Boxes
Load Calculations
Motors & Full Load Amps
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? What is needed for a 200 amp service? What is a sub panel? Can I install a subpanel myself? Can I run a 100 amp subpanel from a 100 amp panel? Can I upgrade my electrical panel without rewiring my house? Do I need 100 or 200 amp service? What size wire do I need for 200 amp service 300 feet away? What is the 80% rule for sub panels? Can you run 220 off a 100 amp panel? What does 100 amp service mean?
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? What are the disadvantages of using THHN wire? Should aluminum wiring in a house be replaced? What exactly is Romex? What does THHN mean in wire? Would a house built in 1979 have aluminum wiring? What wire is best for hot tub wiring? What kind of wire can I run underground without conduit?
Extension Cords & 12V Wiring
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? What is the 80% rule for generators? What is the 20/20/20 rule for generators? Do I wire my solar panels in series or parallel? Is there a federal tax credit for EV charger installation? What are common solar panel wiring mistakes? What will a 5000 watt generator run in a house? What is the 120 rule for solar panels? What is the 33% rule in solar panels? Can you connect 100W and 200W solar panels together? What is the rule of thumb for generator sizing?
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? Can I legally do my own electrical work? What do most electricians charge per hour? What is the difference between NFPA and NEC? How much does it cost to have a 240V outlet installed? How to read the NEC code book? What electrical work can be done DIY? What are the three basic rules of wiring? Why do electricians keep one hand in their pocket? What happens if an inspector finds unpermitted work? What is the 6 12 rule in electrical?