What is wiring hardwire?

A wiring hardwire is the system that directly connects the electronic elements or another object using electrical wires or cables to the power source

Precautions to be taken

First and foremost, switch off the power of the circuit. The voltage is much larger and thus, any carelessness may give a fatal electric shock. Building codes need a hardwired appliance to consist of a power switch and the disconnect position needs to be within the sight of the appliance. Circuit breakers may have a lockout function to lock the breaker to avoid any casualties. Since working on a 240-volt appliance is risky, one should be able to handle the operation and be extremely careful while handling wiring. Also, the technician must be aware of the instructions of the installation process, the colors of wires and other cable connections can change when referred to the manual of the manufacturer.

Color-coded wires in a flexible plastic electrical conduit.
CC0 | Image Credits: https://en.wikipedia.org | KVDP

Hardwire appliances

The four major electrical appliances commonly hardwired are a dishwasher, a cooktop, garbage disposal, and a water heater. A light fixture is an electric device consisting of a lamp to give illumination, and even light fixtures can be hardwired by using the respective standard techniques for different lamps.
Mostly, the 120-volt appliances plug into the conventional receptors. Some 240-volt appliances plug into exclusive 240-volt receptors. Other electrical appliances that use 240 volts and are installed at one particular place are hardwired, i.e.; the cable is attached directly to the circuit. Seldom the garbage disposers and dishwashers can either be plugged in or hardwired, thus refer to the instruction guide before the installation process.
As soon as we remove the old appliance’s cable, it usually takes an hour for the connections. So, the knowledge of stripping, splicing, and joining wires to its terminals is required. Before wiring, one must check that the new equipment does not overload the circuit.
Materials required are a screwdriver, flashlight, the appliance, wire nuts, insulation tape, lineman’s pliers, long-nose pliers, and wire strippers.

Hardwiring a garbage disposal

Below the sink, a split and switched receptacle may be given to the hotplug for a hot-water dispenser, and a switched plug for the garbage disposal. Certain codes require hardwiring of the garbage disposal, then a switched junction box is necessary.
Garbage disposals can be done without cords, which can be wired right towards the junction box (hard-wiring) or using a plug to an appliance cord. Install the armored cable, which is advisable, or any cord that can withstand the amperage rating of the disposal. Splice the wires to the garbage disposal and then, install it below the sink and after that hard-wire or plug the disposal inside a switched receptacle. Disposal must not be over a light circuit, or the lights shall dim when it is operated.

Hardwiring a dishwasher

Conventional Codes may need a dishwasher to be on a separate circuit assigned to only the dishwasher. Certain models plug into receptacles, but many are hardwired. Install a cable that can reach the front end of the dishwasher, then slide it into the hollow space and prepare the plumbing connections. Open the junction box of the dishwasher and splice wires to their leads, and replace the junction box cover.

Hardwiring an electric heater

An electric heater needs a dedicated 240-volt circuit. See the amperage rating and note whether the circuit can withstand a minimum of 120% of the rating. Mostly for homes, a 30-ampere circuit with 10/2 cable is enough. Due to extensive heat production, use an armored cable and ditch the NM cable. Take out the cover plate, splice the wires (neutral wire not required), and then replace the previous cover plate.

Hardwiring an electric cooktop (oven)

An electric cooktop or a wall-mounted oven comprises a 120-volt or a 240-volt circuit, 120 volts to power the inner light fixtures, and a timer, 240 volts for the heating elements. The oven can be wired to the same circuit. Run the cable to the nearest junction box. An electric oven generally has a short length of armored cable, known as a whip. Clamp that whip to the junction box and then make the splices.

Hardwired smoke detector

Hardwired smoke detectors are the best appliances as the sensors are wired in series. When one sensor detects fire and produces sound, simultaneously other sensors also sound the alarm.
Installing hardwired smoke detectors in certain places with battery backup is required, so check the local codes before deciding which types of detectors can be appropriate. Care must be taken to run the cable as it is the toughest task, and never forget to tie it into a single power source. Minimum 5 hours are required to run a cable and install around three detectors, and prior experience to install boxes, strips, splices, and so on will come in handy. Materials required are a voltage tester, drill, fish tape, screwdriver, pliers, wire nuts, insulation tape, boxes,14/3 cable, 14/2 cable, and smoke detectors.

Installation of the boxes is done by creating a hole and placing the 14/2 cable inside the 1st detector in series and 14/3 cable for other detectors. The yellow lead interlinks the system for linking all the detectors. Align the slots of the mounting plate and fix it to the box. Gradually pull the wires through it, and once it is connected in series, the wires are connected similarly. Secure the wire nuts using the insulation tape and slowly push the wires inside each box. Place the detectors, activate batteries, and link the power cable source. One can also place a plug-in carbon monoxide alarm for sensing the poisonous gas emitted after combustion.

Steps to install a dashcam

  1. Locate the fuse box position: Go through the car’s manual for the fuse box position. It depends on the car model for trimming or opening panels to find the fuses.  
  2. Choosing the appropriate fuse slot: Mostly, for all hardwire kits, three wires are connected: one that goes to the ignition switched fuse, the second that goes to the constant fuse, and the third that goes to the metal ground bolt.
  3. Using an add-a-fuse kit: After finding the fuse slots, crimp the hardwire kit on the add-a-fuse kit with a conventional needle node plier. Place the existing fuse into the lower slot of the add-a-fuse, and plug this setup inside the fuse box. For assistance, one can refer to the add-a-fuse guide for better clarity and understanding.
  4. Ground the hardwire kit: After giving power to the hardwire kit, connect the ground wire to it. Avoid a loose ground wire as power problems may occur to the dashcam, and if the ground wire is not suitable, then frequent restarting of the dashcam can occur due to unstable current flow.
  5. Testing the dashcam: After linking the power and ground, plug the kit into the camera and start the vehicle's ignition to check its operation.

Context and Applications

This topic is taught in courses like:

  • Bachelors of Technology (Electrical Engineering)
  • Masters in Science (Electrical and Installation Systems)

Practice Problems

Q1. Which appliance provides illumination?

  1. Light fixture
  2. Dishwasher
  3. Oven
  4. Socket

Correct Option: a

Explanation: Light fixture appliance provides illumination.

Q2. What material(s) is/are required for hardwiring smoke detectors?

  1. Voltage tester
  2. Electrician’s tape
  3. All of these
  4. None of these

Correct Option: c

Explanation: Voltage tester and Electrician’s tape are required for the hardwiring of smoke detectors.

Q3. What is the correct procedure for installing a dashcam?

  1. Choosing the appropriate fuse slot
  2. Locate the fuse box position
  3. Ground the Hardwire kit
  4. Testing the dashcam
  5. Using an Add-a-fuse Kit
  1. iii., v., ii., i, iv.
  2. ii., i., v., iii., iv.
  3. ii., iv., iii., i, v.
  4. i., v., ii., iii, iv.

Correct Option: b

Explanation: The correct procedure for installing a dashcam is to locate the fuse box position, choose the appropriate fuse slot, use an Add-a-fuse Kit, ground the Hardwire kit, and test the dashcam.

Q4. Which cables are used to station the smoke detector?

  1. 14/7 and 14/8
  2. 14/6 and 14/5
  3. 14/4 and 14/3
  4. 14/2 and 14/3

Correct Option: d

Explanation: 14/2 and 14/3 are the cables used to station the smoke detector.

Q5. Which appliance is dedicated to a 240-volt circuit?

  1. Electric heater
  2. Wall-mounted oven
  3. Garbage disposal
  4. None of these

Correct Option: a

Explanation: Electric heater is an appliance dedicated to a 240-volt circuit.

  • Electrical units
  • Built-in sockets
  • Cable Wiring System

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