How deep should wires be chased into walls?

How Deep Should Wires Be Chased into Walls?

Summary

How deep should wires be chased into walls? This article provides answers to this common question about electrical wiring. Here are some key points:

1. Vertical chases should be no deeper than one third of the wall thickness, which is usually around 33mm.

2. It is important not to make any two chases, vertical or horizontal, back to back.

3. When cutting a vertical chase, do not cut any deeper than one third of the total wall depth for stability.

4. Electrical wires should be set back no less than 1-1/4 inches from the edge of the framing lumber.

5. Low-voltage wiring must be buried at least 6 inches deep.

6. UF cable should be placed in a trench at least 24 inches deep, according to the NEC.

7. Underground ducts containing cables operating at a potential above 35,000 volts should be installed at a depth of at least 36 inches.

8. Use a fish stick or fish tape to chase wires through walls, especially if there is insulation present.

9. The width of the chase should depend on the type and number of services to be enclosed, usually not wider than 100mm.

10. Most cables will be at least an inch deep into the wall, so shallow drilling can help avoid damaging wires.

Questions and Answers

1. How deep should wires be in walls?
Vertical chases should be no deeper than one third of the wall thickness.

2. How deep should an electrical chase be?
Vertical chases should not be deeper than ⅓ of the wall thickness.

3. What are the rules for chasing walls?
Rule 1: Do not make any two chases, vertical or horizontal, back to back.
Rule 2: When cutting a vertical chase, do not cut any deeper than one third of the total wall depth.

4. How deep are electrical wires behind drywall?
Per the 2018 International Residential Code, electrical wires should be set back no less than 1-1/4 inches from the edge of the framing lumber.

5. What is the minimum depth for wiring?
Low-voltage wiring must be buried at least 6 inches deep.

6. How deep do wires have to be?
UF cable should be placed in a trench at least 24 inches deep.

7. What is the code for electrical wire depth?
Low-voltage wiring must be buried at least 6 inches deep.

8. How deep is an electrical trench code?
Underground ducts with cables operating above 35,000 volts should be installed at a depth of at least 36 inches.

9. How do you chase wires through walls?
Use a fish stick or fish tape to catch and pull the wires through the space behind the walls, especially if there is insulation present.

10. How wide should a wall chase be?
The width of the chase should depend on the type and number of services to be enclosed, but it is typically not wider than 100mm.

11. How deep are wires in studs?
Most cables will be at least an inch deep into the wall.

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Vertical chases should be no deeper than one third of the wall thickness – with standard 100mm bricks and blocks, that going to be 33mm, which is quite deep anyway – that's not allowing for any plaster coating which could be 10mm so the maximum depth then works out at 36mm from the front face of the plaster.

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Vertical chases indicated B on the above diagram should not be deeper than ⅓ of the wall thickness, or in a cavity wall ⅓ of the relevant leaf.

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Rule 1 – Do not make any two chases, vertical or horizontal, back to back. Rule 2 – When cutting a vertical chase, do not cut any deeper than one third of the total wall depth to ensure stability.

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1-1/4 inches

Per the 2018 International Residential Code, electrical wires should be set back no less than 1-1/4 inches from the edge of the framing lumber. Limiting drilling depth to less than 1-1/4 inches is a good start to reducing the risk of damaging wiring behind the drywall.

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Low-voltage (no more than 30 volts) wiring must be buried at least 6 inches deep. Buried wiring runs that transition from underground to above ground must be protected in conduit from the required cover depth or 18 inches to its termination point above ground, or at least 8 feet above grade.

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Most of the rules involve protection of the wiring from damage. The NEC (National Electrical Code) requires that UF cable be placed in a trench at least 24 inches deep. In most communities, you will have to leave the trench open until the inspector arrives to approve the depth.

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§2827. Raceways (or Ducts) Below Ground.

Underground ducts of rigid metallic steel conduit, Schedule 80 PVC conduit, or equivalent, containing cables operating at a potential above 35,000 volts, shall be installed at a depth of at least 36 inches.

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The fish stick (also called a fish tape or glow rod) is a flexible rod with a small hook attached to the end. Use the fish stick to catch and pull the wires through the space behind the walls. The fish stick helps run the cords and wires through if there's insulation in the wall.

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The width of the chase will depend on the type and number of the services to be enclosed but typically is not usually wider than 100mm. It is not normal practice to cut chases for large size services such as rainwater or sewage pipes. Chases can be cut into brick, plaster and concrete-block walls.

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Most cables will be at least an inch deep into the wall, so by avoiding deep drilling, you can be sure to avoid wires.

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50 mm

If the cable is installed at a depth of less than 50 mm from the surfaces of the wall or partition, it must be installed in the 'safe' zones, as well as having additional protection by an RCD.

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How to Install Underground Electrical Wiring – How Deep Do I Bury the Wire Use direct-burial underground feeder cable at 24-inches deep (or more). You don't need to use conduit at this depth with UF cable, however, you do need to provide PVC conduit on your vertical feeds starting at 18-inches.

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NEC 210-52 states the following (abbreviated for easier digestion): Receptacles are needed in every room of a home such that no point on a wall is over 6′ from an outlet. This means that you need an outlet within 6′ of a doorway or fireplace. A long wall, however, may have up to 12′ between outlets.

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(5) A trench depth of 24 inches minimum is required, as in NEC Table 300-5. The bottom of the trench must be free of loose or projecting stones and debris, and backfill shall be sand or screened earth free of stones and sharp objects for the first six inches above the conductor, as explained in NEC Article 300-5(F).

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Wiring buried inside rigid metal (RMC) or intermediate metal (IMC) conduit must have at least 6 inches of earth cover; wiring in PVC conduit must have at least 18 inches of cover. Backfill surrounding conduit or cables must be smooth granular material without rocks.

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InstructionsCut Box Openings. With the cable routes and box locations planned, cut the openings for the electrical boxes in the drywall.Drill Holes in the Wall Plate.Locate the Drilled Hole.Thread the Fish Tape.Attach the Cable to the Fish Tape.Fish the Cable.Complete the Cable Run.

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The depth of a wall chase is governed by the building regulations in Approved Document A Section 2c. It states that vertical wall chases should be no deeper than 1/3 the thickness of the leaf and that horizontal chases be no deeper than 1/6 of the thickness of the leaf of the wall.

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The National Electrical Code requires holes containing non-metallic cable (often called Romex) or flexible metal-clad cable (the type you buy with the wires already in it) be set back 1-1/4 in. or more from the edge of a stud (Fig. A) to protect the wires from nails and screws. (The 1-1/4-in.

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According to the NEC, PVC conduit requires a minimum cover depth of 18 inches for residential installations and 24 inches for non-residential installations. Please note that these guidelines are based on the NEC, which may not apply to your specific location.

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Depending on the type of direct burial wire and application, there are various rules to prevent accidents. Underground Feeder (UF) cable must be buried at least 24 inches underground. Meanwhile, PVC conduit only has to be buried 12 inches underground.

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60 feet
For 120-volt circuits:

14 AWG	50 feet
12 AWG	60 feet
10 AWG	64 feet
8 AWG	76 feet
6 AWG	94 feet

Sep 25, 2022

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