The different wires in an electric panel are required by the National Electrical Code (NEC) to be color-coded according to their type. Ground wires (grounding conductors) have either a green insulation jacket or they are bare wires. Neutral wires (grounded conductors) should be white. Hot wires (ungrounded conductors) are usually black or red, but are allowed to be other colors except the ones designated for ground, neutral, or a couple of other colors for the phases of 3-phase service.
When a wire color does not match its use, it can be painted or marked with a tape band near the termination, but we rarely see the wires painted. A white tape band indicates that the wire is a neutral, black or red tape indicates hot, and green means ground.
The place where we most often see this overlooked is at 240-volt breakers with #10 copper wires to a water heater or air conditioning condenser. If one of the two hot wires is white, it should have a black band around it near the breaker. Conversely, because only black wires are usually available in the larger sizes of the service cables, the neutral service wire should be wrapped with white tape, like in the photo above.
Also, see our blog post What is the gooey stuff on some of the wire connections in the electric panel?
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Here’s links to a collection of our other blog posts about ELECTRIC PANELS:
• Why is there a 3-phase breaker in a single phase electric panel with only two bus bars?
• What causes copper wires to turn green or black in an electric panel?
• What is the maximum number of circuit breakers allowed in an electric panel?
• When should a corroded or damaged electric panel cabinet or disconnect box be replaced?
• Why is spray paint on the bus bars of an electric panel a safety defect?
• Why is it unsafe to bond neutral and ground wiring at subpanels?
• When was it first required that neutrals and grounds be separated (not bonded) on any panel past the main service panel?
• What are the code requirements for an old fuse panel/box?
• What is a tandem circuit breaker?
• When did arc fault circuit interrupter (AFCI) breakers first become required?
• Can an electric panel be located in a closet?
• Can an electric panel be located in a bathroom?
• Can you add circuit breakers by different manufacturers to an electric panel if they fit?
• My circuit breaker won't reset. What's wrong?
• What is a split bus electric panel?
• How do I identify a combination AFCI (CAFCI) circuit breaker?
• What is three phase electric service?
• What is a reliable way to tell if the electrical service is 3 phase or single phase?
• Can a doorbell transformer be installed inside an electric panel?
• What does a circuit breaker with a yellow or white test button indicate?
• What is the maximum gap allowed between the front of a recessed electric panel box and the wall surface surrounding it?
• How far away should a sink be from an electric panel?
• What are the requirements for NM-cables entering an electric panel box?
• Can a washer or dryer be located in front of an electric panel?
• Why is a fuse box/panel an insurance problem for homebuyers?
• Why is bundled wiring in an electric panel a defect?
• What is the difference between GFCI and AFCI circuit breakers?
• When was the "maximum of six switches or breakers" first required for the main disconnect in a house electrical system?
• What is the voltage rating of a house electrical system?
• Why are old electrical components not always "grandfathered" as acceptable by home inspectors?
• What happens when you press the "TEST" button on a circuit breaker in an electric panel?
• What is a Dual Function Circuit Interrupter (DFCI)?
• What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?
• What is the difference between "grounded" and "grounding" electrical conductors?
• What does it mean when a wire is "overstripped" at a circuit breaker?
• Why is there a GFCI breaker in the electric panel for the bathroom shower light and exhaust fan?
• Why is an old fuse panel dangerous?
• Why are Zinsco and Sylvania-Zinsco electric panels a problem?
• Who is the manufacturer of those "bad" electric panels?
• Can multiple neutral or ground wires be secured under the same terminal in an electric panel?
• What is a lock device on a circuit breaker for?
• Why is the circuit breaker stuck in the middle?
• What is a "missing twistout" at an electric panel?
• Can an electric panel be mounted sideways-horizontally?
• What is a double tap at a circuit breaker?
• What is the right electric wire size for a circuit breaker in an electric panel?
• What is the life expectancy of a circuit breaker?
• My circuit breaker won't reset. What's wrong?
• Why do some breakers in my electric panel have a "TEST" button on them?
• What is the right size electric panel for a house?
• The electric panel is marked "Trilliant" and it's all grey plastic. Is it alright?
Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.