How to Run Electrical Wire in Cabinets for Code Metal or Plastic Conduit

Introduction

Running electrical wiring in cabinets properly is crucial for safety and complying with electrical code requirements. Whether you are using metal or plastic conduit, following code guidelines helps ensure the wiring is protected and installed correctly. This comprehensive guide will walk you through the entire process of running electrical wire in cabinets, from planning to final installation, for a code-compliant and safe electrical system.

Planning the Electrical Wiring Layout

Careful planning is the first step when running electrical wire in cabinets. Consider where you want receptacles, switches, and lighting placed in the cabinet layout. This will determine the wiring routes and length of wire needed. Also factor in any dedicated appliance circuits or outlets required, like for a garbage disposal or built-in microwave.

Determine if you will run wiring through metal or plastic conduit. Both are acceptable but have different installation requirements per code. Plastic is simpler for DIYers as it is more flexible, while metal conduit requires special tools.

Choosing the Right Wire Size and Type

Select the appropriate wire size for the amperage rating on the circuit. For 15 amp small appliance circuits, use standard 14 gauge wire. For 20 amp circuits, upgrade to 12 gauge wire. Use only copper wire, not aluminum, for wiring inside cabinets.

Choose the wiring insulation jacket material:

  • NM (nonmetallic) sheathed cable is common for indoor wiring.
  • UF (underground feeder) cable works for outdoor or damp locations.
  • Use THHN or THWN wire when running inside conduit or for exposed areas.

Check your local electrical code for specific wire sizing requirements.

Working with Conduit

Conduit provides extra protection and avoids exposed wiring. Use metal EMT (electrical metallic tubing) or plastic PVC conduit rated for electrical use. Match the conduit diameter to the number and size of wires inside per code.

Installing Metal Conduit

  • Use conduit straps anchored into the cabinet to secure it. Keep straps spaced a maximum of 5 feet apart.
  • Bend metal conduit gradually using a conduit bender tool to avoid kinks.
  • Ream cut conduit ends smooth to protect wire from sharp edges.
  • Fasten conduit connections together securely using fittings.

Installing Plastic Conduit

  • Plastic conduit is easier to route around corners and bends.
  • Use conduit bodies, elbows, and couplings to connect lengths.
  • Secure with conduit straps but spacing can be increased to 6 feet.
  • Keep at least 6 inches from high heat sources like ovens.

Running and Securing the Wires

Before pulling wires, ensure conduit ends are smooth with no sharp edges. Use plastic grommets when passing conduit through metal holes to protect the wire. Lubricating wire makes it easier to pull through long conduit runs.

When running multiple wires through one conduit, pull all the ground wires first. Then pull the rest of the conductors grouped together.

Clamp the wire snugly using wire connectors when splicing lights, switches, receptacles, and appliances. Secure wires every 4.5 feet inside cabinets using insulated staples or cable clamps attached to the cabinet frame.

Connecting Switches, Outlets and Lights

Follow manufacturer instructions to properly connect wiring to switches, receptacles, and lights. Use electrical boxes as required by code for enclosing splices and wire connections. Install boxes securely into the cabinets.

For lights under cabinets, attach wire through knockouts on the light housing. Connect the wire leads to the terminal screws, matchingpolarity.

Passing Electrical Inspections

Schedule rough-in and final inspections of your electrical work with your local permit office. The inspector will check for proper wire sizing, use of conduit and boxes, and correct installation of devices. This ensures your cabinet wiring meets National Electrical Code for safety.

With careful planning and attention to detail, you can successfully run wiring inside cabinets to code. Following these guidelines helps avoid electrical hazards and pass inspection.

Frequently Asked Questions

What size wire should I use for under cabinet lighting?

14 gauge wire is recommended for under cabinet lighting circuits. This allows enough power for multiple lights on one 15 amp circuit.

Can I run NM cable inside conduit?

Yes, NM cable (Romex) is approved to run inside conduit for extra protection. Just ensure to size the conduit to fit the cable.

What is the best way to route conduit around cabinet corners?

Use gradual conduit bends or sweep elbows when turning corners inside cabinets to avoid kinks in the conduit.

How far apart should I install conduit straps?

For metal conduit, use straps every 5 feet. For plastic conduit, straps can be spaced further apart at 6 feet intervals.

Can I connect copper and aluminum wires together?

No, copper and aluminum wires should never be connected directly together due to galvanic corrosion. Use special connectors or a splice block if joining copper to aluminum.

How do I secure wires inside cabinets without drilling holes?

Self-adhesive cable tie mounts or mounting clips can be used to anchor and route wires securely inside cabinets without drilling.

Conclusion

Running electrical wiring in cabinets properly requires planning and attention to code requirements. Determine the wiring route, select suitable wire size and type for the circuit amperage, and use either metal or plastic conduit for protection. Carefully pulling and connecting the wires and securing them appropriately inside the cabinets ensures a safe and compliant installation that will pass inspection. Following the guidelines in this article will give you confidence for successfully wiring cabinets to supply power to receptacles, lighting, and appliances.


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