NEC rules state that battery cables cannot be of arc welding wire or other unapproved types: only standard building-grade wires may be installed. CEC allows for all types to be used.

Please check our NEEC Section for further reference.

Wiring Color Codes

Color codes for wiring are important in maintaining the right connections during installation and help troubleshooting and future upgrades. Standard color schemes are outlined below:

Bare copper, green or green with a yellow stripe
Attach to any exposed bare metal on PV modules, inverter chassis, frames, circuit breakers and control cabinets to provide a ground connection. There is no electrical current in the ground wire except when there is an electrical fault.

White, natural gray
Cables of these colors can also come in any other color except for green or red, as long as the cable ends are wrapped with colored tape for clear identification as "white". This is the negative, current-carrying wire for the PV, battery, wind turbine or inverter supply. It is connected to the system ground connection.

Red or other color
An electrical system must use red in any two-wire system as the ungrounded or positive conductor. An ungrounded conductor cannot be white or green.

Most DC systems use this standard color code. The AC circuit uses a similar color-coding but the ungrounded conductor is normally black while the second wire is red.