Guides

The why behind each calculation: wire sizing and voltage drop, conduit fill, Ohm's law, off-grid solar and battery banks, generator wattage, 12V RV wiring, EV charging cost and the continuous-load breaker rule.

Sizing Wire

Sizing a wire is really two checks in one: the conductor must carry the current safely (am…

Voltage Drop

Voltage drop is the voltage a wire loses to its own resistance between the source and the …

Conduit Fill

Conduit fill limits how many conductors you may pull into a pipe so they can be installed …

AWG Chart

American Wire Gauge numbers run backwards: the smaller the number, the thicker the wire. B…

Ohm's Law

Ohm's law ties together voltage, current and resistance with one short equation, V = I × R…

Off-Grid Solar

Sizing an off-grid system starts from one number: your daily energy use in watt-hours. Fro…

Battery Bank

A battery bank is sized by three things: how much energy you use, how many days you want t…

MPPT vs PWM

A charge controller sits between the solar array and the battery. PWM is simple and cheap;…

Generator Size

Sizing a generator means adding up the running watts of everything that runs at once, then…

12V Wiring

Twelve-volt DC wiring needs surprisingly heavy cable because low voltage means high curren…

EV Charging Cost

Charging an EV at home costs the energy you add times your electricity rate, plus a small …

Breaker Sizing

A breaker protects the wire, not the appliance. Continuous loads must be sized at 125% of …