NJ Master Plumber cheat sheet

New Jersey plumbing work is governed by the State Uniform Construction Code (N.J.A.C. 5:23), which adopts the National Standard Plumbing Code (NSPC) as the plumbing subcode; local ordinances cannot be less stringent.

A Master Plumber license is required to contract for plumbing work; a Journeyman Plumber may perform work only under a licensed master, and a Plumbing Contractor business must be owned or employed by a licensed master.

Permits are obtained from the local enforcing agency before work begins; ordinary minor repairs and replacement of exposed fixtures with no change in piping generally do not require a permit.

The permit fee is calculated from the plumbing fixture unit count or a flat fee schedule set by the enforcing agency; the permit card must remain on site until the certificate of approval is issued.

Required inspections typically include rough-in (before concealment), underground, and final; concealed work must be inspected before it is covered or the installer may be required to expose it.

A certificate of approval is issued after the final inspection passes; the certificate of occupancy for a new building cannot issue until plumbing final approval is granted.

License renewal and continuing education requirements are administered by the NJ Board of Examiners of Master Plumbers; working with a lapsed or suspended license is a violation subject to penalties.

The enforcing agency may issue a stop-construction order for work performed without a permit, work not conforming to the code, or an imminent hazard; work may not resume until the order is lifted.

Fixture unit: a measure of the load-producing effect of a fixture on the drainage system; one fixture unit equals 1 cubic foot per minute (about 7.5 gpm) of flow.

Drainage fixture unit (DFU) values are assigned per fixture type and are used for drain sizing; supply fixture unit (WSFU) values are used for water pipe sizing.

Developed length: the total length of pipe measured along the centerline of the pipe and fittings from the stack or main to the fixture, used to select pipe size from capacity tables.

A stack is a vertical line of piping; a stack vent is the extension of a soil or waste stack above the highest fixture, and a vent stack is a separate vertical vent line.

A horizontal branch is a drain pipe connecting fixtures to a stack; horizontal pipe in drainage is any pipe installed at a slope less than 45 degrees from horizontal.

A fixture branch is the pipe between the fixture trap and the point of connection to another pipe; a fixture drain is the drain from the trap of a single fixture to a stack or branch.

Referenced standards include ASME A112.19.2 for vitreous china fixtures, ASME A112.18.1/CSA B125.1 for supply fittings, and ASTM standards for pipe and fittings; the NSPC references these by designation.

Backflow definitions: a cross-connection is any actual or potential connection between potable water and a source of contamination; backflow is the reversal of normal flow direction.

Minimum slope for horizontal drainage pipe is 1/4 inch per foot (2 percent) for pipe 2-1/2 inches and smaller and 1/8 inch per foot (1 percent) for pipe 3 inches and larger; larger pipe may use 1/8 inch per foot where the code permits.

Drainage pipe may not be installed at a slope flatter than that required for the size, and horizontal branches must be sized from the DFU load and the slope used.

A building drain is the lowest piping that receives soil and waste from inside the building and conveys it to the building sewer; the building sewer runs from the building wall to the public sewer or private disposal.

Cleanouts are required at the base of each soil or waste stack, at the upper end of every horizontal branch, at each change in direction of more than 135 degrees, and at intervals not exceeding 100 feet in horizontal drains.

A cleanout must be the same size as the pipe it serves for pipe 4 inches and smaller, and not less than 4 inches for larger pipe; cleanouts must be accessible and provided with a gastight cover.

Fixture drains must be sized not less than the trap size of the fixture served; the trap arm length from trap weir to vent must not exceed the developed length permitted for the pipe size.

A horizontal branch with a change in direction of more than 45 degrees that is not a vent connection must be provided with a cleanout; wye fittings are used for drainage direction changes, not sanitary tees, where flow turns.

The building drain and building sewer are sized from the total DFU load using the slope-dependent capacity tables; a 4-inch building drain at 1/4 inch per foot carries roughly 216 DFU.

Every trap must be protected by a vent; vent pipe size is determined from the drainage fixture units on the stack and the developed length of the vent, per the vent sizing table.

The vent stack must extend not less than 6 inches above the roof and be sized not smaller than the stack it serves; the stack vent is the continuation of the soil stack above the highest fixture.

A vent must not be smaller than 1-1/4 inches; the minimum vent size for a water closet is 2 inches, and a vent may not be smaller than half the drain it serves for larger drains.

The trap arm length between the trap weir and the vent connection is limited by pipe size (for example, 2-inch trap arm about 5 feet at 1/4 inch per foot) to prevent self-siphoning.

A common vent may serve two fixtures only when both are on the same floor and the vent is installed per the common vent rules; a wet vent may serve only fixtures on the same floor as permitted by the code.

A vent stack must terminate in open air with a screened or open fitting; vents may not terminate under a window, in a chimney, or within 10 feet of an air intake or property line where the code prohibits it.

An island vent (loop vent) uses a foot vent and a loop above the flood level rim to vent a fixture that cannot be vented conventionally; it must be installed with a cleanout at the base of the foot vent.

A vent offset of more than 45 degrees must be installed using drainage-type fittings and must be vented; flat and dry vents must be installed with the proper slope back to the drain.

Each fixture must have a separate trap with a liquid seal of not less than 2 inches and not more than 4 inches; the trap must be self-cleaning and accessible.

A trap must be installed level and within the distance from the fixture outlet permitted by the code; a fixture with a concealed trap must have a cleanout on the drain.

No trap may be double-trapped or double-vented, and a trap may not be installed on a fixture that is not vented; trap arms must be vented within the permitted length.

Grease interceptors are required for commercial kitchens and other fixtures discharging fats, oils, and grease; they must be sized by capacity and installed outside the building or in a vented location.

A grease interceptor must be provided with a flow-control fitting and must be located so it can be cleaned and inspected; the grease-retaining capacity is based on the fixture flow rate and retention time.

A sand or solids interceptor is required for fixtures that discharge sand, grit, or similar solids; the interceptor must be accessible for cleaning and must not be connected to the sanitary drainage in a way that bypasses it.

An oil separator is required for commercial garages and similar facilities where petroleum products may enter the drainage; the separator must be vented and provided with a cleanout.

Chemical waste must be discharged to a dilution or neutralizing tank where the code requires; neutralized waste may then discharge to the sanitary system, and the tank must be vented and accessible.

Water supply pipe sizing uses the total water supply fixture units (WSFU) and the developed length of the pipe, corrected for pressure loss in fittings and elevation, from the sizing tables.

The minimum residual pressure at a fixture is generally 8 psi for flush tanks and 15 psi for flush valves; the street pressure must be adequate or a booster pump is required.

The developed length of the water distribution system is the longest run from the water meter or source to the farthest fixture, including fittings, used with the sizing table.

Copper tubing, PEX, CPVC, and galvanized steel are accepted materials; lead pipe and lead solder are prohibited, and the lead content of pipe, fittings, and solder is limited by law.

Water pipe must be protected from freezing, and buried pipe must be installed below the frost line or otherwise protected; pipe must be supported at intervals required by the code.

A water service line must be installed at a depth below the frost line or protected, and a main shutoff valve must be installed inside the building near the point of entry.

A pressure-reducing valve is required when the street pressure exceeds the code limit (typically 80 psi); a thermal expansion tank or relief device is required on a closed system.

Water hammer arrestors are required on quick-closing valves and appliances, and the water distribution system must be protected from backflow by the required devices.

Water closets must be of the water-saving type with a flush volume not exceeding 1.6 gallons per flush; urinals are limited to 1.0 gallon per flush.

Fixture clearances: a water closet must have at least 15 inches from the centerline to a side wall and 21 inches in front; the minimum compartment width is 30 inches.

A water heater must be equipped with a temperature and pressure relief valve, piped full size to a safe discharge point, and the discharge pipe must not be trapped or reduced.

A water heater installed in a location where leakage could cause damage must have a pan with a drain; the T&P relief valve must be installed within the top 6 inches of the tank.

Backflow protection is required on the cold water inlet of a water heater where a check valve or other device creates a closed system; a thermal expansion tank or relief device protects the system.

A water heater must be accessible for service, and gas-fired heaters require combustion air, venting, and a sediment trap on the gas line per the gas code.

Fixture fittings must be of an approved type and installed per the manufacturer's instructions; shower valves must be of the pressure-balancing or thermostatic type to limit temperature variation.

A floor drain must have a trap with a seal and must be provided with a trap primer where the trap may evaporate; a fixture with an integral trap must be installed per the listing.

Sanitary drainage conveys sewage and liquid waste; storm drainage conveys rainwater and surface water, and the two systems must not be connected except where the code permits combined systems.

Storm drainage pipe is sized from the rainfall intensity, the roof area, and the runoff coefficient; the roof drain and leader sizing tables use the design rainfall rate for the location.

A roof drain must be installed at the low point of the roof, and the roof must be sloped to the drain; overflow drains or scuppers are required where the code requires secondary drainage.

A storm building drain and storm building sewer must be sized from the total roof area served and the design rainfall intensity; they may not receive sanitary waste.

Sump pumps and ejectors are used where gravity drainage is not possible; a sump pit must be provided with a cover and the discharge must be piped to a legal point of disposal.

A backwater valve is required on sanitary or storm drains where the building drain may be subject to backflow from the public sewer; it must be installed so it can be serviced.

The building sewer must be installed at the required slope and with cleanouts at the required intervals; it must be tested for watertightness before backfilling.

Drainage systems must be tested with a water or air test before concealment; the test pressure and duration are set by the code and witnessed by the inspector.

Fuel gas piping must be sized from the total connected load in Btu/h and the length of run, using the gas pipe sizing tables for the gas type and specific gravity.

Gas pipe must be supported at intervals not exceeding 6 feet for horizontal runs and at each change of direction; it must be protected from physical damage and corrosion.

A shutoff valve must be installed ahead of each gas appliance, and a union or flanged connection must be provided for service; a sediment trap must be installed at the appliance.

Gas piping must be tested for leaks with air or inert gas at the pressure and duration required by the code; the test must be witnessed and the gauge must show no drop.

A gas-fired appliance must be connected with a listed connector, and the connector must not be concealed or pass through a wall, floor, or ceiling.

Combustion air and venting must be provided per the appliance listing and the code; a draft hood or power vent must be installed as required, and the vent must terminate safely.

Gas piping may not be installed in a location where it is subject to damage or in a prohibited space such as a duct or elevator shaft; concealed piping must be protected.

A gas appliance connector must not be longer than the code limit (typically 6 feet for a flexible connector) and must not be used to connect appliances in different rooms.

An air gap is the only absolute backflow protection; it must be at least twice the diameter of the supply pipe and never less than 1 inch above the flood level rim of the receiving fixture.

A reduced-pressure principle backflow preventer (RPZ) is required for high-hazard connections; it must be tested annually by a certified tester and the results reported to the water purveyor.

A double check valve assembly is used for low-hazard connections; a pressure vacuum breaker (PVB) is used for low-hazard where it can be installed above the highest downstream outlet.

A hose bibb vacuum breaker is required on all hose connections, and a backflow preventer is required on boiler feed lines, lawn irrigation systems, and swimming pool fill lines.

A cross-connection is any actual or potential connection between potable water and a source of contamination; backflow is the reversal of normal flow due to backpressure or backsiphonage.

Backsiphonage occurs when negative pressure in the supply line draws contaminant into the potable system; backpressure occurs when downstream pressure exceeds supply pressure.

A backflow prevention device must be installed in an accessible location and protected from freezing; it must not be installed below ground unless in a listed vault.

The water purveyor may require containment protection at the water service and may require isolation protection at each hazard; the property owner is responsible for annual testing.

An air gap is the only absolute backflow protection; it must be at least twice the diameter of the supply pipe and never less than 1 inch above the flood level rim of the receiving fixture.

A reduced-pressure principle backflow preventer (RPZ) is required for high-hazard connections; it must be tested annually by a certified tester and the results reported to the water purveyor.

A double check valve assembly is used for low-hazard connections; a pressure vacuum breaker (PVB) is used for low-hazard where it can be installed above the highest downstream outlet.

A hose bibb vacuum breaker is required on all hose connections, and a backflow preventer is required on boiler feed lines, lawn irrigation systems, and swimming pool fill lines.

A cross-connection is any actual or potential connection between potable water and a source of contamination; backflow is the reversal of normal flow due to backpressure or backsiphonage.

Backsiphonage occurs when negative pressure in the supply line draws contaminant into the potable system; backpressure occurs when downstream pressure exceeds supply pressure.

A backflow prevention device must be installed in an accessible location and protected from freezing; it must not be installed below ground unless in a listed vault.

The water purveyor may require containment protection at the water service and may require isolation protection at each hazard; the property owner is responsible for annual testing.