(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
CHAPTER 3 GENERAL REGULATIONS
1) (Q) A cooling tower is being erected on the roof of a High Rise building. It is being
assembled using parts that are individually listed. Would this installation be allowed
under the 2012 code?
(A) No. The inspector would not allow the installation to be constructed, however, if the
design is sealed by a professional engineer, registered in the State of North Carolina, the
inspector must accept the design and construction of the equipment. Ref: 301.4,
Exception 2 (MC). (2012)
2) (Q) Exhaust Ductwork is installed on the back wall of a garage. It extends out about 4 feet
from the wall into the garage area at an elevation of 6 feet above the floor. How
should the ductwork be protected from vehicle damage per code?
(A) Protection may not be required depending on what types of vehicles are worked on in
the garage, however, reflective tape or a bollard would provide adequate protection.
Ref: 303.4 (MC). (2012)
3) (Q) A tractor trailer has a trailer 11 feet 6 inches high. It is backing into a loading dock
inside a public garage. The ceiling of the garage is 20 feet high. What is the minimum
height to the bottom of the unit heater from the top of the trailer if the unit heater is
installed directly over the trailer?
(A) Unless the manufacturers installation instructions specify a greater height the unit
heater shall be at least 1 foot 6 inches from the top of the trailer to the bottom of the
unit heater. Ref: 304.6 (MC). (2012)
4) (Q) I am installing a wood burning stove in my home. When installing the appliance I
should always be able to use table 308.6 for unlisted equipment to reduce clearances.
Is this a true statement?
(A) No. If the solid fuel burning appliance is labeled with clearances those
clearances shall be used when installing the solid-fuel burning appliance. Ref:
308.7 (MC). (2012)
1st Quarter
Land Use and Environmental Service Agency
(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
5) (Q) What improvement in sizing mechanical equipment for single family dwellings and
duplexes has made it possible in the 2012 code to provide equipment that will help
reduce either under or over sizing equipment?
(A) The use of Manual S for sizing requirements. Ref: 312.1 (MC). (2012)
CHAPTER 4 VENTILATION
1) (Q) To properly balance air flow and have a constant temperature exchange between all
spaces in an occupied building should ventilation be required at a constant value for
building occupants?
(A) NO. Ventilation shall be provided during the periods that a room or space is occupied.
Ref: 401.3 (MC). (2012)
2) Situation: We are working on a Nail Salon that will be going in a building downtown.
From speaking with the owner they will not be doing acrylic nails, and nearly all their
products will be organic. In moving forward with the design it has been determined that
per 2012 NCMC (table 403.3 footnote b) we are not allowed to retcirculate any air,
therefore, one would think all the air conditioning in the space must be exhausted. This is
not the case per DOI. In conversations with Billy Hinton concerning this section, it is his
interpretation that the reference to, “all air supplied to such spaces” meas the
ventilation air supplied, and does not include the air for conditioning the space, therefore,
air for conditioning the space could be returned to the space, but not returned to any
other spaces. Due to the occupancy location on a lower floor of a multi-story building the
designer would like to utilize one of the existing exhaust shafts near the space. One of the
shafts is for toilet exhaust; one shaft is for the pool equipment room. Both exhaust fans
are located on the roof; therefore the shafts are negatively pressurized.
(Q) From reading through Chapter 5 of the code I cannot find any section that will not
allow me to combine the exhaust from the nail salon with either of the existing shafts.
Is this allowed?
1st Quarter
Land Use and Environmental Service Agency
(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
(A) Yes. The ventilation requirement for a nail salon, (as determined by 2012 NC
mechanical code and footnote b in table 404.3), would require mechanical exhaust for
the amount of ventilation air supplied for the space for the nail stations. The code
would not require all the conditioned air be exhausted from the space. The
exhaust from the nail stations may be connected to the exhaust for environmental air
since the system is negatively pressurized. Ref: 403.2.1, Table 403.3 foot note b. (MC).
(2012)
CHAPTER 5 EXHAUSTS SYSTEMS
1) (Q) What would be an adequate amount of make-up air in a residential occupancy if the
dryer is exhausting 50 cfm and the Kitchen hood is exhausting through the roof at the
same time at 40 cfm. How much make- up air would be required?
(A) It depends. Make up air is not required in residential occupancies if natural ventilation
is used per 402, however , if 403 is used then make up air would be required.
Ref: 501.3 exception. (MC). (2012)
2) (Q) The contractor has the installation instructions for dryer vents for a specific make of
Maytag dryer that will be installed in all the apartments in a 40 unit complex. The
Manufacturers’ instructions show lengths of duct runs that exceed the minimum code
but no equivalent length for the fittings used with the dryer duct. Should the inspector
approve the installation?
(A) NO. The inspector should require the contractor to supply an equivalent length chart
for fittings from the manufacturer or re-calculate the runs using the equivalent length
chart in the code (table 504.6.4.1) Ref: 504.6.4.2 (MC). (2012)
3) Situation: A restaurant has installed two barbeque cookers under type I hoods which
exhaust high-medium- & low heat cooking appliances without permits. The food services
inspector discovered the cookers and reported it to the Code Enforcement Department.
Answer a. through e. below.
1st Quarter
Land Use and Environmental Service Agency
(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
a. (Q) The owner says the cookers are safe as installed and they are code compliant. (1) Is
the owner correct? (2) What are the obvious code violations related to this
installation?
(A) (1) The owner is not qualified to determine the safety of the equipment. The restaurant
installed the cookers without plans or permits. Triple fee. Require cookers to meet the
code. Ref: 106.1, 106.2.1 Administrative Code.
(2) Since the cookers use solid fuel and gas for heat for cooking they are classified as
extra-heavy-duty cooking appliances and cannot be located under the same type I
hood with high-medium & low heat appliances. Ref: 507.3.4 MC
b. (Q) Three Type 1 hoods for the cooking equipment are connected to single grease
exhaust duct that exits the building into a covered parking garage. (1) Can the separate
hoods required for the two Extra-heavy-duty cooking appliances be combined with the
existing grease duct exhaust if properly sized? (2) May the grease duct from the extraheavy-duty appliances exhaust into the covered Parking deck?
(A) (1) No. Hoods for the two extra-heavy–duty barbeque cookers shall exit the building
through a separate exhaust duct system. The two cookers may, however, be under the
same Type 1 hood rather than having separate hoods or under a hood or hoods listed
for the application by the manufacturer. The exhaust systems may also be combined
since both are extra-heavy-duty cooking appliances. Ref: 507.2.4, 506.3.5 exception # 4
(2) No. It is a violation to have the current hood system grease duct exit the building
into a parking garage. The new grease duct shall exit the building either vertically or
horizontally to the outside. Ref: 506.3.12.2, 506.3.12.3, 506.5.5
c. (Q) Are there more stringent exhaust requirements for hood exhaust CFM and safety
devices for a hood over an extra-heavy-duty cooking appliance than over high-mediumlow & heat cooking appliances?
(A) Yes, see ventilation tables. Ref: 507.13.1
d. (Q) The manufacturer of the barbeque cookers sends a letter to the Code Administrator
with information on the engineering of the cookers. The letter explains how the cookers
are engineered/designed to make it virtually impossible for a spark or ember to be
exhausted into the exhaust duct system. The letter also states the cookers can be located
1st Quarter
Land Use and Environmental Service Agency
(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
under the same type I hood with high-medium-low heat cooking appliances. Further, the
letter states the information will be included in the manufacturers literature in the future
on the two cookers installed at the restaurant plus 5 other models of cookers with similar
exhaust characteristics. Should the Code Administrator accept the manufacturer’s letter
and approve the cookers? (note: The manufacturer does not have a registered PE on
their staff.)
(A) The code official may accept the letter under the conditions stated above if a
professional engineer who works directly for the factory provides a letter under his seal
that the changes to the literature will be made. The letter must also provide information
as to how the engineering/design of the product is such that a spark or ember can never
be exhausted from the cookers that may cause a grease fire in the ductwork and ignite
fires in heavy-medium or light duty appliances that may also be under the hood. Ref:
105.2 MC
e. (Q) Should the Code Administrator require a third party test that confirms the cookers
will not emit sparks or embers into the grease duct system before he approves the
cookers?
(A)This may be one solution the Code Administrator would allow. Ref: 105.3, 105.3.1,
105.3.2 (MC).
4)(Q) a. What is the new clearance requirement in the 2012 Mechanical Code from operable
openings for all environmental air ducts? b. Can environmental air ducts ever be
considered hazardous or noxious?
(A) a. Three feet, Ref: 501.2.1 (MC)
b. No. Ref: 501.2.1 (MC)
5) (Q) Is exhausted air ever allowed to discharge into walkways or hallways?
(A) No. Ref: 501.2.1.1
1st Quarter
Land Use and Environmental Service Agency
(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
CHAPTER 6 DUCT SYSTEMS
1) (Q) What method can be used to protect the openings in a floor/ceiling or roof/ceiling
assembly where supply air duct from the HVAC unit penetrates the membrane of the
assembly? The type of occupancy is R2 multi-story with type V construction.
Note: The Mechanical Code calls for either a shaft, 607.6.2 #1, or a listed ceiling
radiation damper installed at the ceiling line, 607.6.2 #2, and a listed ceiling radiation
damper installed at the diffuser with no duct attached 607.6.2 #3 (supply plenum).
(A) There is an issue that needs to be addressed with 607.6.2 #2. UL 555C and 607.3.1
would require the radiation damper to have dynamic closure because the unit fan will
continue to run in a fire or smoke condition. 607.3.1 states; “Only fire dampers listed
or labeled for dynamic systems shall be installed in heating, ventilating, an airconditioning systems designed to operated with fans on during a fire.” There is no
shut down required by code for the fan of an air handler in an apartment HVAC
system for example, therefore, the code and UL 555C require a dynamic type
damper for this installation. Per current DOI information a dynamic radiation damper
listed for mounting in the membrane ceiling of the penetration shall be used. As an
alternate method the air handler must be shut down in case of fire. This can be
accomplished by installing a smoke detector in the room adjacent and open to the air
handler and tying it into the smoke detector system of the apartment unit. If you
opted for the smoke detector you still are required to protect the penetration with a
radiation damper, however, since you have provided a means to shut the air down via
the smoke detector you can install a standard radiation damper with static and not
dynamic closure. These are the only two methods approved at the present time.
Ref: 607.6.2 #2, 607.3.1, UL 555 C (MC). (2012)
.
GENERAL INFORMATION (Admin. Code/ Mech. Code Admin. Section/ Policy)
1) (Q) Are permits required for B vents when a re-roof permit is pulled for a building with gas
flues penetrating the roof?
1st Quarter
Land Use and Environmental Service Agency
(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
(A) Yes. Alteration of the vent will require a permit. Ref: (102.1/GS 87-21/GS 153-327
Admin. Code), (102.9 MC). A letter is on the Meckpermit.com web site under the
Mechanical Section click on “news and updates” there is a link on that page for the reroof permit requirements.
2) (Q) Unitary equipment is being installed in a hotel room. E.g. ptac unit in a hotel. Are
permits required for this installation?
(A) If this is a like for like change out permits are not required. If it is a new installation it
should have permits and inspections if it has a hidden drain/ electrical connection.
Ref: 106.1 Administrative codes.
3) (Q) What types of installations do not apply to a refrigeration trade or business and are not
required to be installed by a refrigeration contractor?
(A) House Bill 1105 was recently passed by the General Assembly and signed into law by
Governor Perdue. Changes to the law are summarized as follows:
Section 1 provides that “refrigeration trade or business” does not apply to the following: (1)
The installation of self-contained commercial refrigeration units equipped with an original
equipment manufacturer (OEM) molded plug that does not require the opening of service
valves; (2) the replacement of lamps, fuses and door gaskets; and (3) the installation and
servicing of domestic house-hold self-contained refrigeration appliances equipped with an
OEM molded plug connected to suitable receptacles which have been permanently installed
and do not require the opening of service valves.
4) Situation per Designer: A couple of weeks ago we discussed an old (approx. 35 years)
building (approx. 15,000 sq. ft.) utilizing the original hallway for the return. The ceiling is
extremely tight and there is no real room or access or practical method for adding a return
duct. It is served now by a couple of self-contained single zone units utilizing boiler hot water
and condenser water. We want to replace the ancient units with split systems with the AHU
installed in the same mechanical rooms, with condensing units on the roof and utilizing the
same single zones – no changes to ductwork. There is really no other practical/efficient/cost
effective way to replace the ancient units and get rid of the ancient boilers and cooling
towers. We know we need to submit the mechanical, electrical, and structural but really
need to know about the hallway return before we spend a lot of effort and money. When we
1st Quarter
Land Use and Environmental Service Agency
(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
talked before you indicated that this hallway return could be grandfathered since it is very
close to being like-for-like and there is no work other than replacing the central unit.
(Q) Can we still utilize the hallways for returns?
(A) Yes. Since you are doing away with an ancient cooling tower and boiler you we will
need a split system with a condenser on the roof. There will be no changes outside of
the mechanical room and roof. The installation will be allowed per the conditions
specified. 105.3 (MC)
5) (Q) What are the current requirements for installing Carbon Monoxide detectors in
residential single family dwellings, duplexes and townhomes? Is the requirement
the same for commercial construction?
(A) In general, a change out of fossil fuel equipment in a residence will require the addition
of a Carbon Monoxide Detector per GS. CO2 detectors are currently required adjacent
to each sleeping area per BCC rules. An all electric residence is exempt unless
they currently have an existing attached garage or are adding a new attached garage
or have or are adding a fireplace. If these conditions are present Carbon Monoxide
Detectors are required even if they do not have fossil fuel equipment. Fossil fuel fired
equipment such as a hot water heaters in a hut attached to the house are exempt from
the CO2 detector requirements, however, a gas pack or other appliance that is
communicating with the inside of the house is not exempt. The “special exemptions”
only apply to single family dwellings, duplexes and townhomes. All other
commercial occupancies shall have Carbon Monoxide Detectors per current code
requirements. If a “plug in type or table model” Carbon Monoxide detector will be
used the inspector shall have ready access to the detector on the premises. It must be
in the box and readily accessible for the inspector. Having an empty box for
the inspector or taping a box to the inside of a window is not acceptable.
1st Quarter
Land Use and Environmental Service Agency
(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
1st Quarter
Land Use and Environmental Service Agency
(Code Enforcement)
NC Mechanical Code 2012
st
1 Quarter Q&A in Brown, 3rd Quarter Q&A in blue
nd
th
2 Quarter Q&A in green, 4 Quarter Q& A in red
1st Quarter
Land Use and Environmental Service Agency