ADOPTS WITH AMENDMENTS:

International Residential Code 2015 (IRC 2015)

Part I — Administrative

Part II — Definitions

Part III — Building Planning and Construction

Part IV — Energy Conservation

Part V — Mechanical

Part VI — Fuel Gas

Part VII — Plumbing

Part VIII — Electrical

Part IX — Referenced Standards

Heads up: There are no amended sections in this chapter.

Chapter 13 General Mechanical System Requirements

AMENDMENT
This section has been amended at the state or city level.
The text of this chapter is extracted from the 2018 edition of the North Carolina Mechanical Code and has been modified where necessary to conform to the scope of application of the North Carolina Residential Code for One- and Two-Family Dwellings. The section numbers appearing in parentheses after each section number are the section numbers of the corresponding text in the North Carolina Mechanical Code.
The provisions of this chapter shall govern the installation of mechanical systems not specifically covered in other chapters applicable to mechanical systems. Installations of mechanical appliances, equipment and systems not addressed by this code shall comply with the applicable provisions of the International Mechanical Code and the International Fuel Gas Code.
In flood hazard areas as established by Table R301.2(1), mechanical appliances, equipment and systems shall be located or installed in accordance with Section R322.1.6.

M1301.2 (301.3) Identification

AMENDMENT
This section has been amended at the state or city level.
Each length of pipe and tubing and each pipe fitting utilized in a mechanical system shall bear the identification of the manufacturer as required by the listing or standard for the piping or tubing.
Materials shall be installed in strict accordance with the standards under which the materials are accepted and approved. In the absence of such installation procedures, the manufacturer's instructions shall be followed. Where the requirements of referenced standards or manufacturer's instructions do not conform to minimum provisions of this code, the provisions of this code shall apply.

M1301.4 Plastic Pipe, Fittings and Components

AMENDMENT
This section has been amended at the state or city level.
Piping, tubing and fittings shall comply with the applicable referenced standards, specifications and performance criteria of this code and shall be identified in accordance with Section M1301.2. Piping, tubing and fittings shall either be tested by an approved third-party testing agency or certified by an approved third-party certification agency.

M1302.1 (301.7) Listed and Labeled

AMENDMENT
This section has been amended at the state or city level.
Appliances regulated by this code shall be listed and labeled for the application in which they are installed and used, unless otherwise approved in accordance with Section R104.11.

Exceptions:
  1. Listing and labeling of equipment and appliances used for refrigeration shall be in accordance with Section 1101.2 of the North Carolina Mechanical Code.
  2. Field erected equipment shall be deemed acceptable, provided it is assembled using listed components and parts, if the design thereof is by a registered design professional.

M1303.1 (301.9) Label Information

AMENDMENT
This section has been amended at the state or city level.
A permanent factory-applied nameplate(s) shall be affixed to appliances on which shall appear, in legible lettering, the manufacturer's name or trademark, the model number, a serial number and the seal or mark of the testing agency. A label also shall include the following:
  1. Electrical appliances. Electrical rating in volts, amperes and motor phase; identification of individual electrical components in volts, amperes or watts and motor phase; and in Btu/h (W) output and required clearances.
  2. Absorption units. Hourly rating in Btu/h (W), minimum hourly rating for units having step or automatic modulating controls, type of fuel, type of refrigerant, cooling capacity in Btu/h (W) and required clearances.
  3. Fuel-burning units. Hourly rating in Btu/h (W), type of fuel approved for use with the appliance and required clearances.
  4. Electric comfort-heating appliances. The electric rating in volts, amperes and phase; Btu/h (W) output rating; individual marking for each electrical component in amperes or watts, volts and phase; and required clearances from combustibles.
  5. Maintenance instructions. Required regular maintenance actions and title or publication number for the operation and maintenance manual for that particular model and type of product.

M1304.1 (301.12) Fuel Types

AMENDMENT
This section has been amended at the state or city level.
Fuel-fired appliances shall be designed for use with the type of fuel to which they will be connected and the altitude at which they are installed. Appliances that comprise parts of the building mechanical system shall not be converted for the use of a different fuel, except where approved and converted in accordance with the manufacturer's instructions. The fuel input rate shall not be increased or decreased beyond the limit rating for the altitude at which the appliance is installed.

M1305.1 (306.1) Appliance Access for Inspection Service, Repair and Replacement

AMENDMENT
This section has been amended at the state or city level.
Appliances shall be accessible for inspection, service, repair and replacement without removing permanent construction, other appliances, or any other piping or ducts not connected to the appliance being inspected, serviced, repaired or replaced. A level working space not less than 30 inches deep and 30 inches wide (762 mm by 762 mm) shall be provided in front of the control side to service an appliance.

M1305.1.1 Furnaces and Air Handlers

AMENDMENT
This section has been amended at the state or city level.

M1305.1.2 (306.2) Appliances in Rooms

AMENDMENT
This section has been amended at the state or city level.
Appliances installed in a compartment, alcove, basement or similar space shall be accessed by an opening or door and an unobstructed passageway measuring not less than 24 inches (610 mm) wide and large enough to allow removal of the largest appliance in the space, provided there is a level service space of not less than 30 inches (762 mm) deep and the height of the appliance, but not less than 30 inches (762 mm), at the front or service side of the appliance with the door open.

M1305.1.3 (306.3) Appliances in Attics and Above Hard Ceilings

AMENDMENT
This section has been amended at the state or city level.
Attics containing appliances shall be provided with an opening and a clear and unobstructed passageway large enough to allow removal of the largest component of the appliance, but not less than 30 inches (762 mm) high and 22 inches (559 mm) wide and not more than 20 feet (6096 mm) long measured along the centerline of the passageway from the opening to the appliance. The passageway shall have continuous solid flooring in accordance with Chapter 5 not less than 24 inches (610 mm) wide. A level service space not less than 30 inches (762 mm) deep and 30 inches (762 mm) wide shall be present along all sides of the appliance where access is required. The clear access opening dimensions shall be not less than of 20 inches by 30 inches (508 mm by 762 mm), and large enough to allow removal of the largest component of the appliance.

Exceptions:
  1. The passageway and level service space are not required where the appliance (or disassembled appliance) can be serviced and removed through the required opening.
  2. Where the passageway is not less than 6 feet (1829 mm) high for its entire length, the passageway shall not be limited in length.

M1305.1.3.1 Electrical Requirements

AMENDMENT
This section has been amended at the state or city level.

M1305.1.3.1 (306.3.1) Lighting Outlet and Receptacle

AMENDMENT
This section has been amended at the state or city level.
For reference and coordination purposes only, refer to the North Carolina Electrical Code, Article 210.63 for receptacles, and Article 210.70(3) for lighting outlet and switch locations.

M1305.1.4 (306.4) Appliances Under Floors and Exterior Grade Installations

AMENDMENT
This section has been amended at the state or city level.
Underfloor spaces containing appliances shall be provided with an unobstructed passageway large enough to remove the largest component of the appliance, but not less than 22 inches (559 mm) high and 36 inches (914 mm) wide, nor more than 20 feet (6096 mm) long measured along the centerline of the passageway from the opening to the appliance. A level service space not less than 30 inches (762 mm) deep and 30 inches (762 mm) wide shall be present at the front or service side of the appliance. If the depth of the passageway or the service space exceeds 12 inches (305 mm) below the adjoining grade, the walls of the passageway shall be lined with concrete or masonry extending 4 inches (102 mm) above the adjoining grade in accordance with Chapter 4. The rough-framed access opening dimensions shall be not less than 22 inches high by 30 inches wide (559 mm by 762 mm), and large enough to remove the largest component of the appliance.

Exceptions:
  1. The passageway is not required where the level service space is present when the access is open, and the appliance can be serviced and removed through the required opening.
  2. Where the passageway is not less than 6 feet (1829 mm) high unobstructed and not less than 6 feet (1929 mm) high for its entire length, the passageway shall not be limited in length.

M1305.1.4.1 (304.10.1) Ground Clearance

AMENDMENT
This section has been amended at the state or city level.

M1305.1.4.1.1 (304.10.1) Exterior Grade Installations

AMENDMENT
This section has been amended at the state or city level.
Equipment and appliances installed above grade level shall be supported on a solid base or approved material a minimum of 2 inches (51 mm) thick.

M1305.1.4.1.2 (304.10.2) Under-Floor Installation

AMENDMENT
This section has been amended at the state or city level.
Suspended equipment shall be a minimum of 6 inches (152 mm) above the adjoining grade. See Section M1601.4.8 for ductwork support heights.

M1305.1.4.1.3 (304.10.3) Crawl Space Supports

AMENDMENT
This section has been amended at the state or city level.
A support shall be provided at each corner of the unit not less than 8 inches by 8 inches (203.2 mm by 203.2 mm). The unit shall be supported a minimum of 2 inches (51 mm) above grade. When constructed of brick, the bricks shall be mortared together. All units stacked shall be mortared together. Fabricated units, formed concrete, or other approved materials shall be permitted.

M1305.1.4.1.4 (304.10.4) Drainage

AMENDMENT
This section has been amended at the state or city level.
Below-grade installations shall be provided with a natural drain or an automatic lift or sump pump. For pit requirements, see Section M1305.1.4.2.

M1305.1.4.2 Excavations

AMENDMENT
This section has been amended at the state or city level.

M1305.1.4.2 (303.7) Pit Locations

AMENDMENT
This section has been amended at the state or city level.
Appliances installed in pits or excavations shall not come in direct contact with the surrounding soil. The sides of the pit or excavation shall be held back not less than 12 inches (305 mm) from the appliance. Where the depth exceeds 12 inches (305 mm) below adjoining grade, the walls of the pit or excavation shall be lined with concrete or masonry. Such concrete or masonry shall extend not less than 4 inches (102 mm) above adjoining grade and shall have sufficient lateral load-bearing capacity to resist collapse. The appliance shall be protected from flooding in an approved manner.

M1305.1.4.3 Electrical Requirements

AMENDMENT
This section has been amended at the state or city level.
A luminaire controlled by a switch located at the required passageway opening and a receptacle outlet shall be installed at or near the appliance location in accordance with the North Carolina Electrical Code. Exposed lamps shall be protected from damage by location or lamp guards.

M1306.1 (304.9) Appliance Clearance

AMENDMENT
This section has been amended at the state or city level.
Heat-producing equipment and appliances shall be installed to maintain the required clearances to combustible construction as specified in the listing and manufacturer's instructions. Such clearances shall be reduced only in accordance with Section M1306. Clearances to combustibles shall include such considerations as door swing, drawer pull, overhead projections or shelving and window swing, shutters, coverings and drapes. Devices such as doorstops or limits, closers, drapery ties or guards shall not be used to provide the required clearances.


Note: "A" equals the required clearance with no protection. "B" equals the reduced clearance permitted in accordance with Table M1306.2. The protection applied to the construction using combustible material shall extend far enough in each direction to make "C" equal to "A."
FIGURE M1306.1
REDUCED CLEARANCE DIAGRAM

M1306.2 Clearance Reduction

AMENDMENT
This section has been amended at the state or city level.
The reduction of required clearances to combustible assemblies or combustible materials shall be based on Section M1306.2.1 or Section M1306.2.2.

TABLE M1306.2
REDUCTION OF CLEARANCES WITH SPECIFIED FORMS OF PROTECTIONa, c, d, e, f, g, h, i, j, k, l
TYPE OF PROTECTIVE
ASSEMBLYa
REDUCED CLEARANCE WITH PROTECTION
(inches)b
Horizontal
combustible
assemblies located
above the heat
source
Horizontal combustible
assemblies located beneath the
heat source and all vertical
combustible assemblies
Required clearance
to combustibles
without protection
(inches)a
Required clearance to
combustibles without protection
(inches)
36 18 9 6 36 18 9 6
Galvanized sheet steel, having a minimum thickness of 0.0236 inch (No. 24 gage), mounted on 1-inch glass fiber or mineral wool batt reinforced with wire on the back, 1 inch off the combustible assembly 18 9 5 3 12 6 3 3
Galvanized sheet steel, having a minimum thickness of 0.0236 inch (No. 24 gage), spaced 1 inch off the combustible assembly 18 9 5 3 12 6 3 2
Two layers of galvanized sheet steel, having a minimum thickness of 0.0236 inch (No. 24 gage), having a 1-inch air-space between layers, spaced 1 inch off the combustible assembly 18 9 5 3 12 6 3 3
Two layers of galvanized sheet steel, having a minimum thickness of 0.0236 inch (No. 24 gage), having 1 inch of fiberglass insulation between layers, spaced 1 inch off the combustible assembly 18 9 5 3 12 6 3 3
0.5-inch inorganic insulating board, over 1 inch of fiberglass or mineral wool batt, against the combustible assembly 24 12 6 4 18 9 5 3
31/2-inch brick wall, spaced 1 inch off the combustible 12 6 6 6
31/2-inch brick wall, against the combustible wall 24 12 6 5
For SI: 1 inch = 25.4 mm, 1 pound per cubic foot = 16.019 kg/m3, °C = [(°F)-32/1.8], 1 Btu/(h × ft2 × °F/in.) = 0.001442299 (W/cm2 × °C/cm).
  1. Reduction of clearances from combustible materials shall not interfere with combustion air, draft hood clearance and relief, and accessibility of servicing.
  2. Clearances shall be measured from the surface of the heat producing appliance or equipment to the outer surface of the combustible material or combustible assembly.
  3. Spacers and ties shall be of noncombustible material. Spacers and ties shall not be used directly opposite appliance or connector.
  4. Where all clearance reduction systems use a ventilated air space, adequate provision for air circulation shall be provided as described. (See Figures M1306.1 and M1306.2.)
  5. There shall be not less than 1 inch between clearance reduction systems and combustible walls and ceilings for reduction systems using ventilated air space.
  6. If a wall protector is mounted on a single flat wall away from corners, adequate air circulation shall be permitted to be provided by leaving only the bottom and top edges or only the side and top edges open with not less than a 1-inch air gap.
  7. Mineral wool and glass fiber batts (blanket or board) shall have a minimum density of 8 pounds per cubic foot and a minimum melting point of 1,500°F.
  8. Insulation material used as part of a clearance reduction system shall have a thermal conductivity of 1.0 Btu inch per square foot per hour °F or less. Insulation board shall be formed of noncombustible material.
  9. There shall be not less than 1 inch between the appliance and the protector. The clearance between the appliance and the combustible surface shall not be reduced below that allowed in this table.
  10. All clearances and thicknesses are minimum; larger clearances and thicknesses are acceptable.
  11. Listed single-wall connectors shall be permitted to be installed in accordance with the terms of their listing and the manufacturer's instructions.
  12. For limitations on clearance reduction for solid-fuel-burning appliances see Section M1306.2.3.

For SI: 1 inch = 25.4 mm.
FIGURE M1306.2
WALL PROTECTOR CLEARANCE REDUCTION SYSTEM

M1306.2.1 (308.4.1) Labeled Assemblies

AMENDMENT
This section has been amended at the state or city level.
The allowable clearance reduction shall be based on an approved reduced clearance protective assembly that has been tested and bears the label of an approved agency.

M1306.2.2 (308.4.2) Reduction Table

AMENDMENT
This section has been amended at the state or city level.
Reduction of clearances shall be in accordance with the appliance manufacturer's instructions and Table M1306.2. Forms of protection with ventilated air space shall conform to the following requirements:
  1. Not less than 1-inch (25 mm) air space shall be provided between the protection and combustible wall surface.
  2. Air circulation shall be provided by having edges of the wall protection open not less than 1 inch (25 mm).
  3. If the wall protection is mounted on a single flat wall away from corners, air circulation shall be provided by having the bottom and top edges, or the side and top edges not less than 1 inch (25 mm).
  4. Wall protection covering two walls in a corner shall be open at the bottom and top edges not less than 1 inch (25 mm).
Table M1306.2 shall not be used to reduce the clearance required for solid-fuel appliances listed for installation with minimum clearances of 12 inches (305 mm) or less. For appliances listed for installation with minimum clearances greater than 12 inches (305 mm), Table M1306.2 shall not be used to reduce the clearance to less than 12 inches (305 mm).

M1306.2.4 (308.4.2.2) Masonry Chimneys

AMENDMENT
This section has been amended at the state or city level.
The clearance reduction methods specified in Table M1306.2 shall not be utilized to reduce the clearances required for masonry chimneys as specified in Chapter 10 and the International Building Code.

M1306.2.5 (308.4.2.3) Chimney Connector Pass-Throughs

AMENDMENT
This section has been amended at the state or city level.
The clearance reduction methods specified in Table M1306.2 shall not be utilized to reduce the clearances required for chimney connector pass-throughs as specified in Table M1803.3.5 and Figure M1306.1.


FIGURE M1306.2.5
CHIMNEY CONNECTOR SYSTEMS

M1306.2.6 (308.4.2.4) Masonry Fireplaces

AMENDMENT
This section has been amended at the state or city level.
The clearance reduction methods specified in Table M1306.2 shall not be utilized to reduce the clearances required for masonry fireplaces as specified in Chapter 10 and the International Building Code.

M1307.1 (304.1) General

AMENDMENT
This section has been amended at the state or city level.
Equipment and appliances shall be installed as required by the terms of their approval, in accordance with the conditions of the listing, the manufacturer's installation instructions and this code. Manufacturer's installation instructions shall be available on the job site at the time of inspection.

M1307.2 Anchorage of Appliances

AMENDMENT
This section has been amended at the state or city level.

M1307.3 (304.3) Elevation of Ignition Source

AMENDMENT
This section has been amended at the state or city level.
Appliances having an ignition source shall be elevated such that the source of ignition is not less than 18 inches (457 mm) above the floor in garages. For the purpose of this section, rooms or spaces that are not part of the living space of a dwelling unit and that communicate with a private garage through openings shall be considered to be part of the garage.

Exception: Elevation of the ignition source is not required for appliances that are listed as flammable-vapor-ignition resistant.

M1307.3.1 Protection From Impact

AMENDMENT
This section has been amended at the state or city level.
Appliances located in private garages and carports shall be installed with a minimum clearance of 6 feet (1829 mm) above the floor. Appliances located out of the normal path of travel are not required to be protected.

Exception: The requirements of this section shall not apply where the appliances are protected from motor vehicle impact and installed in accordance with Section M1307.3.

M1307.4 (304.5) Hydrogen Generating and Refueling Operations

AMENDMENT
This section has been amended at the state or city level.
Ventilation shall be required in accordance with Section M1307.4.1, M1307.4.2 or M1307.4.3 in private garages that contain hydrogen-generating appliances or refueling systems. For the purpose of this section, rooms or spaces that are not part of the living space of a dwelling unit and that communicate directly with a private garage through openings shall be considered to be part of the private garage.
Indoor locations intended for hydrogen-generating or refueling operations shall be limited to a maximum floor area of 850 square feet (79 m2) and shall communicate with the outdoors in accordance with Sections M1307.4.1.1 and M1307.4.1.2. The maximum rated output capacity of hydrogen-generating appliances shall not exceed 4 standard cubic feet per minute (1.9 L/s) of hydrogen for each 250 square feet (23 m2) of floor area in such spaces. The minimum cross-sectional dimension of air openings shall be 3 inches (76 mm). Where ducts are used, they shall be of the same cross-sectional area as the free area of the openings to which they connect. In those locations, equipment and appliances having an ignition source shall be located so that the source of ignition is not within 12 inches (305 mm) of the ceiling.
Two permanent openings shall be constructed within the garage. The upper opening shall be located entirely within 12 inches (305 mm) of the ceiling of the garage. The lower opening shall be located entirely within 12 inches (305 mm) of the floor of the garage. Both openings shall be constructed in the same exterior wall. The openings shall communicate directly with the outdoors and shall have a minimum free area of 1/2 square foot per 1,000 cubic feet (1.7 m2/1000 m3) of garage volume.
In calculating free area required by Section M1307.4.1, the required size of openings shall be based on the net free area of each opening. If the free area through a design of louver or grille is known, it shall be used in calculating the size opening required to provide the free area specified. If the design and free area are not known, it shall be assumed that wood louvers will have a 25-percent free area and metal louvers and grilles will have a 75-percent free area. Louvers and grilles shall be fixed in the open position.
Indoor locations intended for hydrogen-generating or refueling operations shall be ventilated in accordance with Section 502.16 of the International Mechanical Code. In these locations, equipment and appliances having an ignition source shall be located so that the source of ignition is below the mechanical ventilation outlet(s).
As an alternative to the provisions of Sections M1307.4.1 and M1307.4.2, the necessary supply of air for ventilation and dilution of flammable gases shall be provided by an approved engineered system.

M1307.5 Electrical Appliances

AMENDMENT
This section has been amended at the state or city level.
Electrical appliances shall be installed in accordance with Chapters 14, 15, 19, and 20 of this code and the North Carolina Electrical Code.
Potable water and drainage system connections to equipment and appliances regulated by this code shall be in accordance with Chapters 29 and 30.

M1308.1 (302.3, 302.5) Drilling and Notching

AMENDMENT
This section has been amended at the state or city level.
Wood-framed structural members shall be drilled, notched or altered in accordance with the provisions of Sections R502.8, R602.6, R602.6.1 and R802.7. Holes in load-bearing members of cold-formed steel light-frame construction shall be permitted only in accordance with Sections R505.2.6, R603.2.6 and R804.2.6. In accordance with the provisions of Sections R505.3.5, R603.3.4 and R804.3.3, cutting and notching of flanges and lips of load-bearing members of cold-formed steel light frame construction shall not be permitted. Structural insulated panels (SIPs) shall be drilled and notched or altered in accordance with the provisions of Section R610.7.

M1308.2 (305.5) Protection Against Physical Damage

AMENDMENT
This section has been amended at the state or city level.
Where piping will be concealed within light-frame construction assemblies, the piping shall be protected against penetration by fasteners in accordance with Sections M1308.2.1 through M1308.2.3.

Exception: Cast iron piping and galvanized steel piping shall not be required to be protected.

M1308.2.1 Piping Through Bored Holes or Notches

AMENDMENT
This section has been amended at the state or city level.
Where piping is installed through holes or notches in framing members and is located less than 11/2 inches (38 mm) from the framing member face to which wall, ceiling or floor membranes will be attached, the pipe shall be protected by shield plates that cover the width of the pipe and the framing member and that extend 2 inches (51 mm) to each side of the framing member. Where the framing member that the piping passes through is a bottom plate, bottom track, top plate or top track, the shield plates shall cover the framing member and extend 2 inches (51 mm) above the bottom framing member(s) and 2 inches (51 mm) below the top framing member(s).

M1308.2.2 Piping in Other Locations

AMENDMENT
This section has been amended at the state or city level.
Where piping is located within a framing member (i.e. steel studs) and is less than 11/2 inches (38 mm) from the framing member face to which wall, ceiling or floor membranes will be attached, the piping shall be protected by shield plates that cover the width and length of the piping. Where piping is located outside of a framing member and is located less than 11/2 inches (38 mm) from the nearest edge of the face of the framing member to which the membrane will be attached, the piping shall be protected by shield plates that cover the width and length of the piping.
Shield plates shall be of steel material having a thickness of not less than 0.0575 inch (1.463 mm) (No. 16 gage).

M1308.3 (305.5) Piping Support

AMENDMENT
This section has been amended at the state or city level.
Piping systems shall be supported in accordance with Section M2101.9.
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