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NC Plumbing Code 2011
March 2011
Table of Contents
Chapter 1 Administration
Chapter 3 General Regulations
Chapter 5 Water Heaters
Chapter 7 Sanitary Drainage
Chapter 9 Vents
Chapter 11 Storm Drainage
POLICY
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Chapter 2 Definitions
Chapter 4 Fixtures, Fau & Fit.
Chapter 6 Water Supply & Dist.
Chapter 8 Ind./Special Waste
Chapter 10 Traps, Inter. & Sep.
Appendix A-H
OTHER
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Chapter 3 General Regulations:
1)
(Q) Is a check valve required on the water supply to a mobile home?
No. Water supply piping shall be directly connected to the mobile home.
The utility requirements are the same as any single family dwelling
in Mecklenburg County.
Ref: 301.3, 301.4 & North Carolina Mobile Home Code requirements.
1)
(Q) What is the maximum height of the curb on a shower pan threshold?
(A) There is not a maximum height for a non-handicap shower threshold.
The requirement is; “the remaining side (threshold) shall wrap over the
curb”.
Ref: 417.4
(B) The maximum height for the threshold of a handicap shower, (either rollin or transfer type) is ½ inch. The exception is for existing facilities where
structural reinforcement would be disturbed. If that is the case a
maximum threshold of 2 inches would be allowed.
Ref: ICC/ANSI A117.1- 2003
2)
(Q) Can standard drywall coverings be used on the walls of a shower enclosure
with shower head?
(A) No. The wall area shall be constructed of smooth, non-corrosive, nonabsorbent, and water proof materials to a height of 6 feet.
Ref: 417.4.1
3) 
(Q) I have an old existing apartment building three stories high that have no
washer and dryer facilities. I can alter the plumbing piping to provide a 2
inch drain for the washers. I have no practical way to install a horizontal 3
inch drain for the washers. Will the re-hab code offer me any relief so these
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Chapter 4 Fixturers, Faucets and Fixture Fittings:
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washers may be installed?
(A) No. The Re-hab code offers the designer no relief from the horizontal 3
Inch drain requirement, however, the plumbing official may look at the
existing DWV system to determine the feasibility of accommodating the
washers before making a final determination. Ref: 406.3
4) 
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(Q) Is a drain required for an outside shower used on a pool deck that has only
a cold water connection?
(A) No. The shower is not used for bathing and has no hot water
connection. The water could be considered clear water waste under
normal circumstances and can drain into the same system that is used for
the pool deck drainage. Similar in some respects to Emergency Showers
and Eyewash Stations.
Ref: 411
Chapter 5 Water Heaters:
(Q) may a plastic safety pan be used for a gas fired instantaneous W/H?
(A) Yes, provided that the water heaters minimum distance from
combustible material is maintained. Ref: Manufacturers Instructions
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1)
2) 
(Q) What is the minimum size of a water heater pan drain per the current North
Carolina Plumbing Code?
(A) The plumbing code minimum in 504.7.1 requires a ¾ inch drain minimum
This is incorrect and is a misprint in the code. The correct minimum size is 1
Inch. See DOI letter From Henry Webster Chief Plumbing Engineer for the
State Department of Insurance Office of the State Fire Marshall.
Chapter 6 Water Supply & Distribution:
1)
(Q) What is the maximum distance a fixture supply pipe may be from the fixture it
serves?
(A) Section 604.5 states 72”.
2)
(Q) When are water hammer arrestors required?
(A) 604.9 Water hammer. The flow velocity of the water distribution system
shall be controlled to reduce the possibility of water hammer. A water-
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hammer arrestor shall be installed where quick-closing valves (clothes
washers and dishwashers) and metallic piping is used. The water-hammer
arrestor shall not be required on any valves where plastic piping is used for
water distribution. Water-hammer arrestors shall be installed in accordance
with the manufacturer’s specifications. Water-hammer arrestors shall
conform to ASSE 1010.
3)
(Q) Does the Code require a water distribution system to be sanitized?
(A) ? (No) 602.3.4 purged and disinfected, 610.1 purged of deleterious matter.
4) 
(Q) Is an expansion device required on a tankless water heater?
(A) No. An expansion device is required only if there is a tank type water
heater installed in the residence. An expansion device is not required if hot
water distribution is from a tankless water heater. Ref: 607.3
Chapter 8 Indirect/Special Waste:
1)
(Q) What is a sacristy and what special allowances apply?
(A) It is one use where the drain is allowed to discharge directly into a
drywell outside of the structure.
2)
(Q) Can the tail piece of a lavatory or sink be used as a direct connection for
the drainage from an ice maker or medical equipment?
No. An air gap shall be provided and the waste shall discharge into an
approved receptor to protect against backflow.
Ref: Section 801.2, 802.1, and 802.1.6
3) 
(Q) Do all acid waste neutralization tanks require a monitoring device with
alarm?
(A) Yes. We require monitoring and alarms on all neutralization tanks
installed in Mecklenburg County. Ref: Code Interpretation Letter &
702.5/803.2,803.5.
4)  (Q) Can the discharge from a three compartment sink in a commercial
Restaurant be pumped to an indirect waste receptor in a remote location?
(A) Yes. The three compartment sink shall discharge through a flow control
fitting and a point of use grease interceptor before terminating in the lift
station. The lift station pumped discharge shall have a check valve and
terminate over an indirect waste receptor which must be visible from the
three compartment sink location. Ref: 802.1.1, 802.2.1
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Chapter 10 Traps, Interceptors & Seperators:
1)
(Q) What is required for laundry drain protection for lint, buttons or strings? 1st
(A) Laundries other than a single family residence, shall be equipped with a
manufactured device (not field fabricated) that will limit lint, buttons or
string larger than ½” from entering the drainage system.
2)
(Q) Is a separate draw off storage tank allowed to be installed as part of an
oil/water separator installation?
Yes. When circumstances exist on a site that would not permit the full
storage tank capacity calculated for an integral storage oil/water separator to
be installed, an integral separator sized to meet the minimum capacity of the
code may be installed with an additional draw off tank to store the remaining
capacity calculated for the separator. All other requirements for oil/water
separators installed in Mecklenburg County shall remain the same.
Ref: 1003.1, 1003.2, 1003.4, & 1003.4.2
1)
(Q) How do vertical walls affect roof drain calculations?
(A) 1106.4 Vertical walls. In sizing roof drains and storm drainage piping,
one-half of the area of any vertical wall that diverts rainwater to the roof
shall be added to the projected roof area for inclusion in calculating the
required size of vertical conductors, leaders and horizontal storm drainage
piping.
2) 
(Q) I am attaching a handmade metal box I designed to a 4 inch overflow roof
drain that terminates on the side wall of an apartment building. I am installing a
screen in the box to restrict the flow so the water will not be pouring down the
side of the building and staining the brick finish. Does this installation meet the
code?
No. The size of the drainage pipe is reduced in the direction of flow. The
fitting is not approved and retards the direction of flow. The fitting has
shoulders and/or reductions that retard flow. Strainers are allowed on roof
surfaces only for overflow drains this is a side wall mounted fitting.
Ref: 1101.5, 1101.6, 1102.7, 1105.1, 1107.2
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Chapter 11 Storm Drainage:
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1)
(Q) What is the maximum depth that a two-way C/O may be installed?
(A) The maximum depth shall not exceed 24” below grade. If deeper depths
are required, then an additional combination may be placed as close as
possible downstream of the required building drain/sewer junction C/O.
2) 
(Q) A single family home is connected to a septic tank. Can a dishwasher or
washing machine be connected to the drainage system of the house? Can the
washing machine be connected to a dry well?
(A)The homeowner would be required to contact the Environmental Health
Department for Mecklenburg County. They regulate the installation, repair,
and alteration of the septic tank systems in Mecklenburg County.
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