Electrical – the minimum distance wiring must be behind a tile backsplash


I have a log home and would like to correct the kitchen counter-top receptacles. I have discovered the following problems that necessitate rewiring the entire kitchen (new cabinets/countertops were installed recently by previous owner).

  1. No GFCI.
  2. Wire splits somewhere inaccessible (probably behind counter — requiring me to GFCI each receptacle.)
  3. Only one circuit
  4. Not enough boxes to meet the 2ft/4ft rule.
  5. Wire is run through the cabinets — visible (not behind the cabinets)

I've allocated two circuits and plan to put the fridge and three receptacles on one and the gas range and four on the other. I will be adding two boxes. I plan to router a channel for the wires in the solid log wall above the counter tops and then install the backsplash over the wire. I am curious if hardiboard and tile (between 3/4 to 1 inch total of material) is sufficient protection for the wiring. Does code require some kind of metal protection or min distance from the surface? …in the event someone tries to drill a hole in the backsplash? I want to make the groove depth as small as possible as one wall is an exterior load-carrying wall.

Best Answer

Protecting the Cable

National Electrical Code 2014

Article 300 Wiring Methods

I. General Requirements

300.4 Protection Against Physical Damage.

(F) Cables and Raceways Installed in Shallow Grooves. Cable- or raceway-type wiring methods installed in a groove, to be covered by wallboard, siding, paneling, carpeting, or similar finish, shall be protected by 1.6 mm (1/16 in.) thick steel plate, sleeve, or equivalent or by not less than 32-mm (11/4-in.) free space for the full length of the groove in which the cable or raceway is installed.

Exception No. 1: Steel plates, sleeves, or the equivalent shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing.

So you have a couple options.

Free Space

Run the groove deep enough, so that there's 1 1/4" of free space in front of the cable.

Steel Protection

Protect the cable using a 1/16" steel plate, or sleeve. Or install the cable in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing.

Dividing the Circuits

National Electrical Code 2014

Article 210 Branch Circuits

I. General Provisions

210.11 Branch Circuits Required.

(C) Dwelling Units.

(1) Small-Appliance Branch Circuits. In addition to the number of branch circuits required by other parts of this section, two or more 20-ampere small-appliance branch circuits shall be provided for all receptacle outlets specified by 210.52(B).

III. Required Outlets

210.52 Dwelling Unit Receptacle Outlets.

(B) Small Appliances.

(1) Receptacle Outlets Served. In the kitchen, pantry, breakfast room, dining room, or similar area of a dwelling unit, the two or more 20-ampere small-appliance branch circuits required by 210.11(C)(1) shall serve all wall and floor receptacle outlets covered by 210.52(A), all countertop outlets covered by 210.52(C), and receptacle outlets for refrigeration equipment.

Exception No. 2: The receptacle outlet for refrigeration equipment shall be permitted to be supplied from an individual branch circuit rated 15 amperes or greater.

(2) No Other Outlets. The two or more small-appliance branch circuits specified in 210.52(B)(1) shall have no other outlets.

Exception No. 2: Receptacles installed to provide power for supplemental equipment and lighting on gas-fired ranges, ovens, or counter-mounted cooking units.

So as far as your plan for dividing up the circuits, you're spot on.