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Sri Lanka NVQ L3 Plumber study materials
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Sri Lanka NVQ L3 Plumber practice questions

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Question 1Occupational Health, Safety and Environment on Plumbing Sites

Before entering a confined space such as a septic tank or deep inspection chamber on a plumbing site, what is the correct first step?

  1. Lower a torch to check whether the space looks clear
  2. Obtain a permit and test the atmosphere for oxygen and toxic gases Correct answer.
  3. Start work immediately if the job is expected to take under ten minutes
  4. Ask a workmate to hold the ladder steady at the opening

Explanation

Confined spaces can hold oxygen-deficient or toxic atmospheres that are invisible and can kill within minutes, so entry must be authorised by a permit and the air must be tested with a calibrated gas meter before anyone descends. Rescue arrangements and a standby person are also required. Visual inspection or a short duration does not remove the hazard.

Question 2Occupational Health, Safety and Environment on Plumbing Sites

Which item of personal protective equipment is most important when cutting galvanised steel pipe with a powered abrasive saw?

  1. A high-visibility vest
  2. Heavy cotton work gloves
  3. Close-fitting impact goggles or a face shield Correct answer.
  4. Steel-capped rubber boots

Explanation

An abrasive saw throws hot metal particles and abrasive grit at high speed towards the face and eyes, so eye and face protection is the primary control. Gloves, vests and boots protect other parts of the body but do not stop flying debris from injuring the eyes.

Question 3Occupational Health, Safety and Environment on Plumbing Sites

A plumber must carry a 6 m length of 50 mm steel pipe across a busy site compound. What is the safest method?

  1. Carry it vertically alone so it takes up less width
  2. Drag it along the ground behind you
  3. Carry it horizontally at waist height with a colleague at the other end Correct answer.
  4. Rest it on one shoulder and walk quickly through the compound

Explanation

Long pipe carried by two people at low level stays controlled, keeps the load balanced and reduces the chance of striking overhead lines, scaffolding or other workers. One person carrying a long length cannot see both ends and risks shoulder strain and collisions.

Question 4Occupational Health, Safety and Environment on Plumbing Sites

When mixing solvent-based pipe adhesive in a small unventilated bathroom, what control should be applied first?

  1. Put on a dust mask
  2. Increase ventilation by opening the window and using forced air Correct answer.
  3. Cover the floor with plastic sheeting
  4. Work faster to reduce exposure time

Explanation

Solvent vapours are the main hazard, and the hierarchy of control puts engineering measures such as ventilation ahead of administrative measures. Removing or diluting the vapour at source protects everyone in the space, whereas masks and speed of work are less reliable.

Question 5Occupational Health, Safety and Environment on Plumbing Sites

What does a safety data sheet (SDS) for a drain-cleaning chemical tell a plumber?

  1. The warranty period of the container
  2. The recommended pipe diameter for the product
  3. The wholesale price and supplier discount terms
  4. The hazards, required PPE and first-aid measures for the product Correct answer.

Explanation

A safety data sheet is the standard document that communicates a chemical's hazards, safe handling, exposure controls, first-aid and spill response. It is not a commercial or technical sizing document, so its content is entirely about health and safety information.

Question 6Occupational Health, Safety and Environment on Plumbing Sites

A worker receives a small splash of acid drain cleaner in the eye. What should happen first?

  1. Apply an eye ointment from the site first-aid box
  2. Rub the eye with a clean cloth to remove the chemical
  3. Irrigate the eye with clean water from an eyewash or gentle stream for at least 15 minutes Correct answer.
  4. Wait to see whether the eye becomes painful before acting

Explanation

Chemical eye splashes must be flushed immediately with copious clean water, continuing for at least 15 minutes while the eyelids are held open, and the casualty must then be sent for medical assessment. Delay or rubbing worsens tissue damage.

Question 7Occupational Health, Safety and Environment on Plumbing Sites

Why must a plumber never use a metal ladder near overhead power lines?

  1. Metal conducts electricity and could provide a path to earth for the current Correct answer.
  2. Metal ladders are more expensive to replace
  3. Metal ladders cannot be fitted with non-slip feet
  4. Metal ladders are heavier than fibreglass ones

Explanation

A metal ladder is a conductor, so contact with a live overhead line can pass current through the ladder and the worker to earth, causing electrocution. Non-conductive ladders and safe approach distances are the required controls near overhead lines.

Question 8Occupational Health, Safety and Environment on Plumbing Sites

A plumber is about to solder joints in a roof void where dry timber and insulation batts are stored. Which precaution is most appropriate?

  1. Use a heat mat or shield and keep a fire extinguisher and watch for smouldering after finishing Correct answer.
  2. Open a window and continue soldering as normal
  3. Ask the client to leave the building during the work
  4. Wet the timber lightly before starting

Explanation

Hot-work in a combustible environment needs a fire watch, shielding of nearby combustibles and suitable extinguishing equipment, plus a check of the area after work stops because smouldering can start a fire later. Ventilation or dampening timber does not control the ignition source.

Question 9Occupational Health, Safety and Environment on Plumbing Sites

Why are trench excavations for underground drainage particularly dangerous even when they look shallow and stable?

  1. Walls can collapse suddenly without warning and bury a worker Correct answer.
  2. They always contain flammable gas
  3. They attract vermin that bite workers
  4. They are usually too narrow for tools

Explanation

Excavation sides can fail without warning, and a cubic metre of soil weighs over a tonne, so a collapse can crush or suffocate a worker very quickly. Support, battering back the sides and safe access are required, and spoil must be kept back from the edge.

Question 10Occupational Health, Safety and Environment on Plumbing Sites

What is the correct way to store compressed gas cylinders used for plumbing heating work?

  1. Upright, secured against falling, with valves closed and caps fitted when not in use Correct answer.
  2. Chained together loosely in a locked vehicle overnight
  3. Stored next to oily rags to keep them dry
  4. Laid flat in a corridor so they cannot topple

Explanation

Cylinders must be kept upright and restrained so they cannot fall and shear the valve, with caps fitted and valves closed during storage and transport. They must also be separated from oxidisers and combustibles and kept in a ventilated area.

Question 11Occupational Health, Safety and Environment on Plumbing Sites

A plumber needs to work at height on a scaffold platform to install rainwater downpipes. Which control is required before use?

  1. Stand on the top guardrail to reach the highest bracket
  2. Remove guardrails where they obstruct the pipe run
  3. Confirm the scaffold has a current handover tag and guardrails with toe boards Correct answer.
  4. Climb the outside of the scaffold to save time

Explanation

Scaffolds must be erected and inspected by competent people, with a handover certificate or tag showing the last inspection, and must have guardrails, toe boards and safe access. Altering the scaffold or climbing its frame defeats the fall protection.

Question 12Occupational Health, Safety and Environment on Plumbing Sites

Which practice best reduces the risk of musculoskeletal injury when tightening large pipe unions by hand?

  1. Use a correctly sized wrench and keep the work at waist height where possible Correct answer.
  2. Kneel on the floor and reach overhead to tighten the union
  3. Grip the pipe with one hand and strike the wrench with the other
  4. Use an extension bar on a small wrench and twist with the back

Explanation

Correct tool sizing and good working height reduce the force needed and keep the body in a neutral posture. Extension bars, twisting, overhead reaching and striking tools all increase strain or the risk of sudden loss of control.

Question 13Occupational Health, Safety and Environment on Plumbing Sites

A worker is found collapsed inside a manhole. A colleague is about to climb down to pull them out. What should the colleague do?

  1. Climb down immediately and hold their breath
  2. Enter with a dust mask and pull the worker up quickly
  3. Lower a rope and ask the collapsed worker to tie it on
  4. Stay out, raise the alarm and use rescue equipment only if trained and breathing apparatus is available Correct answer.

Explanation

Most confined-space multiple fatalities occur when untrained rescuers enter without protection and are overcome by the same atmosphere. The correct action is to raise the alarm, call for trained rescuers with breathing apparatus and rescue equipment, and never enter unprotected.

Question 14Occupational Health, Safety and Environment on Plumbing Sites

When using a petrol-driven compactor or generator in a partly enclosed basement, what is the main hazard and control?

  1. Carbon monoxide build-up, controlled by moving the equipment outside and ventilating the space Correct answer.
  2. Noise, controlled by ear defenders alone
  3. Vibration, controlled by job rotation only
  4. Fuel spillage, controlled by a drip tray only

Explanation

Petrol engines produce carbon monoxide, an odourless gas that can accumulate to lethal levels in enclosed or partly enclosed spaces. The correct control is to site engine-driven plant outdoors and ventilate the work area; hearing and vibration controls do not address the fatal risk.

Question 15Occupational Health, Safety and Environment on Plumbing Sites

What is the purpose of a permit-to-work system for high-risk plumbing tasks such as confined-space entry or hot work?

  1. To record the hours each worker spends on site for payroll
  2. To formally record that hazards have been assessed and controls are in place before work starts Correct answer.
  3. To transfer legal responsibility to the client
  4. To replace the need for a site induction

Explanation

A permit-to-work is a formal documented control that confirms the hazard assessment, isolations and precautions are in place before a high-risk task begins and that the area is made safe afterwards. It does not replace training, induction or legal duties.

Question 16Occupational Health, Safety and Environment on Plumbing Sites

A plumber discovers damaged asbestos insulation board around a pipe in an older building. What is the correct immediate action?

  1. Seal the area with tape and continue working nearby
  2. Wet the board and carry on fitting the new pipe
  3. Stop work, leave the area undisturbed and report it so a licensed assessor can deal with it Correct answer.
  4. Break off the damaged section and bag it for disposal

Explanation

Damaged asbestos-containing material can release fibres that cause fatal lung disease, so work must stop, the area must be left undisturbed and the find must be reported for assessment and removal by trained, licensed specialists. Disturbing or sealing and continuing still risks fibre release.

Question 17Occupational Health, Safety and Environment on Plumbing Sites

Which statement correctly describes the use of residual current devices (RCDs) on a plumbing site?

  1. An RCD removes the need for earthing of tools
  2. An RCD should be bypassed if it trips repeatedly during a shift
  3. Portable tools should be supplied through a 30 mA RCD that is tested before use Correct answer.
  4. An RCD prevents all electrical faults from occurring

Explanation

A 30 mA RCD rapidly disconnects the supply if current leaks to earth, greatly reducing the severity of electric shock, and it must be tested with its test button before use. It does not replace earthing, prevent faults, and must never be bypassed.

Question 18Occupational Health, Safety and Environment on Plumbing Sites

What is the correct disposal route for waste solvent-based cement, contaminated rags and empty containers from a plumbing job?

  1. Pour liquid residues down the foul drain and bin the containers
  2. Burn the rags on site to reduce volume
  3. Mix everything into general building waste for the skip
  4. Segregate and consign them as hazardous waste through an authorised carrier with a waste transfer note Correct answer.

Explanation

Solvent-based products and contaminated materials are hazardous waste and must be segregated, stored safely and consigned through an authorised carrier with the correct documentation. Draining, burning or mixing with general waste causes pollution and breaches waste duty of care.

Question 19Occupational Health, Safety and Environment on Plumbing Sites

A plumber is pressure-testing a newly installed pipework system. Which precaution protects people in the area?

  1. Leave the test unattended while collecting materials
  2. Barricade the test area and exclude people while pressure is held Correct answer.
  3. Test at the highest possible pressure to finish quickly
  4. Ask occupants to stand behind a door during the test

Explanation

Stored energy in a pressurised system can release violently if a joint or fitting fails, so the test area must be barricaded, people excluded and the test supervised. Over-pressurising or leaving the test unattended increases the chance of injury.

Question 20Occupational Health, Safety and Environment on Plumbing Sites

Which combination of factors best shows that a task on a plumbing site should be treated as high risk requiring a written risk assessment?

  1. The task requires the use of more than one power tool
  2. The task is being done by a subcontractor rather than an employee
  3. The task involves several hazards that interact, such as work at height near live services Correct answer.
  4. The task is likely to take more than one working day

Explanation

Risk assessment focuses on the severity and likelihood of harm, and interacting hazards such as height work close to live electrical or gas services clearly raise the risk level. Duration, employment status and tool count are not measures of risk.

Question 21Occupational Health, Safety and Environment on Plumbing Sites

A worker is using a cartridge-type sealant gun and complains of headache and dizziness in a sealed plant room. What is the most likely cause and correct response?

  1. Solvent vapour exposure; stop work, evacuate and ventilate before resuming with suitable controls Correct answer.
  2. Carbon dioxide build-up; open a door slightly and continue
  3. Low blood sugar; take a break and return without changes
  4. Dehydration; drink water and continue working

Explanation

Headache and dizziness in a sealed space during solvent-based work point to vapour exposure, and the response is to stop work, get the person to fresh air and ventilate the space before resuming with appropriate extraction and respiratory protection. Continuing work risks loss of consciousness.

Question 22Occupational Health, Safety and Environment on Plumbing Sites

Two plumbers disagree about whether a gas-fired appliance can be commissioned. One wants to proceed because the pressure test passed, the other is unsure about the flue. What is the correct decision?

  1. Do not commission until the flue is verified as safe by a competent person Correct answer.
  2. Commission because the pressure test is the only relevant check
  3. Commission and note the flue concern in the handover file
  4. Ask the client to sign a waiver and then commission

Explanation

Commissioning a gas appliance requires all safety checks, including flue performance and ventilation, to be confirmed by a competent person, because a faulty flue can release carbon monoxide into the building. A passed pressure test covers gas tightness only, and a client waiver cannot make an unsafe installation acceptable.

Question 23Occupational Health, Safety and Environment on Plumbing Sites

On a site where several trades work at once, what is the most effective way to control the risk of a plumber being struck by an excavator?

  1. Plan segregated pedestrian routes and exclusion zones, with a trained banksman directing the machine Correct answer.
  2. Rely on machine operators to sound the horn before moving
  3. Ask plumbers to wear high-visibility clothing and keep working
  4. Post a warning sign at the site entrance only

Explanation

The most effective control is physical separation of people and plant through planned routes and exclusion zones, supported by a trained banksman. High-visibility clothing and horns are useful secondary measures but rely on being seen or heard in time.

Question 24Occupational Health, Safety and Environment on Plumbing Sites

A plumber's work requires an isolation of the electrical supply to a pump before replacing a valve. Which sequence is correct?

  1. Ask a colleague to watch the switch and start work
  2. Isolate, lock off and prove dead at the point of work before starting Correct answer.
  3. Isolate and attach a warning tag only, without proving dead
  4. Switch off at the local switch and begin work immediately

Explanation

Safe isolation requires isolating the supply, locking it off with a personal lock and proving the circuit dead with an approved voltage tester at the point of work. Switching off without locking or proving dead allows accidental re-energisation or a wrong circuit.

Question 25Plumbing Tools, Equipment and Materials

When selecting a hacksaw blade for cutting a 50 mm diameter galvanised steel water pipe, which blade specification is most appropriate?

  1. A 24 TPI flexible blade with a hardened high-speed steel edge Correct answer.
  2. A 32 TPI blade intended for thin-wall copper tube
  3. A tungsten carbide grit blade for cast iron
  4. A 14 TPI wood-cutting blade with coarse set teeth

Explanation

Medium-pitch blades of about 18 to 24 TPI give a good balance of speed and finish on standard steel pipe, and a hardened HSS edge resists wear on galvanised surfaces. At least three teeth should be in contact with the wall thickness at all times to avoid tooth stripping.

Question 26Plumbing Tools, Equipment and Materials

Which tool is the correct choice for tightening a compression nut on a 15 mm copper fitting without damaging the nut?

  1. A pipe wrench with serrated jaws
  2. A Stillson wrench
  3. A cold chisel and hammer
  4. An adjustable spanner set to the nut flats Correct answer.

Explanation

Compression nuts are hexagon fittings and must be tightened on the flats with a spanner of the correct size so the faces are not chewed. Serrated gripping tools crush and score the nut and can distort the olive inside.

Question 27Plumbing Tools, Equipment and Materials

A plumber needs to join two lengths of 110 mm PVC soil pipe permanently. Which material is designed for this joint?

  1. Silicone sealant smeared on the socket
  2. PTFE tape wound around the spigot
  3. Solvent cement applied to both mating surfaces Correct answer.
  4. Linseed oil putty packed into the socket

Explanation

PVC soil pipe is joined by solvent welding, where cement softens both surfaces so they fuse into a single continuous joint. The cement is applied to the spigot and socket, then the pipe is pushed home and held briefly.

Question 28Plumbing Tools, Equipment and Materials

What is the main purpose of a pipe bending spring when working with copper tube?

  1. To support the tube wall internally and prevent it collapsing during the bend Correct answer.
  2. To heat the tube so it softens before bending
  3. To measure the exact bend angle required
  4. To clean oxide from the inside of the tube

Explanation

A bending spring is inserted into the bore so the tube wall is supported from inside, which stops it flattening or kinking as it is bent. The correct spring size must match the tube bore, and it is removed by twisting after the bend.

Question 29Plumbing Tools, Equipment and Materials

Which personal protective equipment is essential when using a blowtorch to solder copper pipe indoors?

  1. Leather gloves, eye protection and a fire extinguisher within reach Correct answer.
  2. A dust mask and ear defenders
  3. A full-face respirator with acid-gas cartridges
  4. Anti-vibration gloves only

Explanation

Soldering with an open flame creates fire risk and hot flux spatter, so leather gloves, goggles and immediate access to a fire extinguisher are required. A fire watch and removal of combustible material around the joint are also standard precautions.

Question 30Plumbing Tools, Equipment and Materials

Which type of valve is installed to allow one-directional flow and prevent backflow in a domestic cold water supply?

  1. A gate valve
  2. A pressure reducing valve
  3. A double check valve Correct answer.
  4. A drain cock

Explanation

A double check valve contains two independent non-return mechanisms and is used to prevent backflow contamination of the supply. It is a recognised backflow prevention device for domestic installations.

Question 31Plumbing Tools, Equipment and Materials

A plumber is cutting a thread on a 25 mm galvanised steel pipe. Which sequence of equipment is used?

  1. Tube bender, then a compression fitting
  2. Pipe reamer, then a flaring tool
  3. Pipe cutter, then a die stock with the correct die, lubricated with cutting oil Correct answer.
  4. Hacksaw, then a tap wrench with a plug tap

Explanation

Steel pipe threads are cut with a die held in a die stock, after the pipe is cut square and reamed. Cutting oil is applied continuously to cool the die and produce a clean thread.

Question 32Plumbing Tools, Equipment and Materials

Which material is most suitable for underground cold water service pipe because it resists corrosion and is flexible?

  1. Medium-density polyethylene (MDPE) Correct answer.
  2. Annealed copper in long straight lengths
  3. Cast iron
  4. Galvanised mild steel

Explanation

MDPE is the standard material for buried service pipes because it does not corrode, tolerates ground movement and can be joined with mechanical fittings. It is supplied in coils so fewer joints are needed underground.

Question 33Plumbing Tools, Equipment and Materials

What does the term 'water hammer' describe, and which component is fitted to reduce it?

  1. Vibration from a loose pump, reduced by a flexible coupling
  2. Scale build-up in the pipe, reduced by a strainer
  3. Noise from air in the pipe, reduced by a foot valve
  4. Pressure surge from sudden valve closure, reduced by an arrestor Correct answer.

Explanation

Water hammer is the pressure surge caused when moving water is stopped abruptly, producing a bang and stress on fittings. A water hammer arrestor contains a trapped air or gas cushion that absorbs the surge.

Question 34Plumbing Tools, Equipment and Materials

When assembling a screwed joint in steel pipe, what is the correct order of operations?

  1. Coat both threads with solvent cement before assembly
  2. Tighten dry first, then wrap tape over the assembled joint
  3. Apply PTFE tape to the male thread, hand-tighten, then tighten with a wrench Correct answer.
  4. Apply PTFE tape to the female thread, then force the pipe in

Explanation

Thread sealant such as PTFE tape is wrapped around the male thread in the direction of the thread helix, then the joint is assembled by hand before final tightening with a wrench. This prevents cross-threading and ensures the tape is drawn into the joint.

Question 35Plumbing Tools, Equipment and Materials

Which property makes cross-linked polyethylene (PEX) popular for domestic hot and cold distribution?

  1. It is flexible, resists scale and tolerates expansion Correct answer.
  2. It can be solvent-welded like PVC
  3. It is rigid and can be threaded
  4. It has a higher melting point than copper

Explanation

PEX is flexible, so it can be routed in long runs with few fittings, and it resists scale and corrosion while accommodating thermal expansion. It is joined with mechanical or press fittings, never solvent cement.

Question 36Plumbing Tools, Equipment and Materials

A plumber must support a horizontal 22 mm copper pipe run. What is the practical purpose of the pipe clips?

  1. To insulate the pipe against frost
  2. To hold the pipe at the correct fall and stop movement and noise Correct answer.
  3. To increase water pressure in the pipe
  4. To earth the pipe electrically

Explanation

Clips secure the pipe at spacing that keeps it aligned and at the required gradient, and they stop vibration and expansion noise. Plastic clips also allow slight movement while supporting the weight.

Question 37Plumbing Tools, Equipment and Materials

Which fitting is used to connect a copper tube to a threaded tap shank?

  1. A tap connector with a fibre or rubber washer Correct answer.
  2. An end feed stop end
  3. A straight coupling
  4. A compression tee

Explanation

A tap connector joins copper tube to a threaded tap shank and seals against the tap face with a fibre or rubber washer. The tube side is made off by compression or solder depending on the connector type.

Question 38Plumbing Tools, Equipment and Materials

What is the correct procedure for pressure testing a new domestic water installation before commissioning?

  1. Apply soap solution to joints without pressurising
  2. Run the taps briefly and check for drips
  3. Fill with water, bleed air, pressurise to the specified test pressure and hold with a gauge Correct answer.
  4. Fill with air only and listen for leaks

Explanation

A water pressure test requires the system to be filled, air vented, then raised to the specified test pressure and held while a gauge monitors for loss. Air must be removed because trapped air makes the test unreliable.

Question 39Plumbing Tools, Equipment and Materials

Which material is normally used for a soil and waste stack because it is lightweight, corrosion-resistant and easily jointed?

  1. Galvanised steel
  2. Lead
  3. Asbestos cement
  4. uPVC Correct answer.

Explanation

uPVC is the standard material for soil and waste stacks: it is light, does not corrode and is jointed with solvent cement or push-fit rings. It also gives a smooth bore that resists blockage.

Question 40Plumbing Tools, Equipment and Materials

A plumber is choosing a tool to cut 15 mm copper tube with a clean square end. Which tool is correct and why?

  1. A wheel-type tube cutter, because it produces a square cut with minimal burr Correct answer.
  2. A hacksaw with a fine blade, because it leaves a burr-free edge
  3. A bolt cropper, because it shears the tube cleanly
  4. A reciprocating saw with a coarse wood blade

Explanation

A wheel-type tube cutter rolls a cutting wheel around the tube and produces a square, controlled cut on copper. The burr left inside must then be removed with a reamer before jointing.

Question 41Plumbing Tools, Equipment and Materials

A plumber finds a compression joint leaking on a 15 mm copper pipe. Which action best addresses the most likely cause before replacing the fitting?

  1. Reduce the system pressure permanently
  2. Apply silicone around the outside of the nut
  3. Wrap more PTFE tape over the nut
  4. Check that the pipe end is clean, square and fully inserted, then re-tighten the nut Correct answer.

Explanation

Most compression leaks come from a damaged olive, a scored or out-of-square pipe end, or the tube not being fully inserted. Cleaning and squaring the pipe and re-tightening the nut on the olive usually restores the seal.

Question 42Plumbing Tools, Equipment and Materials

A plumber must join MDPE service pipe to a copper tail underground. Which approach is correct?

  1. Use a purpose-made mechanical transition fitting rated for buried service Correct answer.
  2. Solder the MDPE to the copper with lead-free solder
  3. Solvent-weld the MDPE directly to the copper
  4. Clamp the two pipes together with a hose clip and tape

Explanation

MDPE and copper are dissimilar materials and cannot be welded or soldered together, so a mechanical transition fitting designed for buried service is used. The fitting must be rated for the pressure and protected against ground movement.

Question 43Plumbing Tools, Equipment and Materials

A plumber is installing a thermostatic mixing valve on a domestic hot water outlet. Which installation detail is essential for it to control temperature correctly?

  1. Matching the hot and cold connections to the valve markings and keeping the strainers and check valves in place Correct answer.
  2. Removing the integral strainers to increase flow
  3. Fitting it on the cold inlet only
  4. Installing it downstream of a single outlet tap

Explanation

A thermostatic mixing valve blends hot and cold, so the hot and cold ports must be connected as marked and the integral strainers and check valves must remain fitted. The strainers protect the thermostatic element and the check valves prevent cross-flow between supplies.

Question 44Plumbing Tools, Equipment and Materials

A plumber is selecting fixings to support a run of 110 mm cast iron drainage pipe beneath a concrete soffit. Which fixing choice is most appropriate?

  1. Metal expansion anchors or through-bolts rated for the pipe weight Correct answer.
  2. Plastic plugs and wood screws into the concrete
  3. Double-sided adhesive pads
  4. Cable ties looped around a nearby conduit

Explanation

Cast iron drainage pipe is heavy and needs brackets fixed with metal expansion anchors or through-bolts that transfer the load into the concrete. Plastic plugs and adhesives cannot carry the weight and will pull out.

Question 45Reading and Interpreting Plumbing Drawings, Specifications and Standards

On a plumbing drawing, a soil pipe is shown as a thick continuous line and a vent pipe as a thinner dashed line. What does a dashed line most commonly indicate in this convention?

  1. A pipe under pressure testing
  2. A pipe carrying hot water only
  3. A pipe that has been deleted from the design
  4. A pipe hidden above the ceiling or inside a wall Correct answer.

Explanation

In plumbing drafting conventions, dashed (hidden) lines represent components not visible in the view, such as pipes concealed in walls or above ceilings. Line weight and line type together convey both the service and the visibility of the pipe.

Question 46Reading and Interpreting Plumbing Drawings, Specifications and Standards

A drawing legend shows '100 mm dia. uPVC SWR'. What does the abbreviation SWR denote in this context?

  1. Soil, waste and rainwater Correct answer.
  2. Standard water riser
  3. Sealed water return
  4. Storm water reduction

Explanation

SWR stands for soil, waste and rainwater, the drainage service category of pipe. It tells the plumber the pipe is intended for gravity drainage of soil, waste and rainwater rather than for a pressure supply.

Question 47Reading and Interpreting Plumbing Drawings, Specifications and Standards

A floor plan shows a scale of 1:50. A pipe run measures 80 mm on the drawing. What is the actual installed length?

  1. 0.4 m
  2. 16.0 m
  3. 40.0 m
  4. 4.0 m Correct answer.

Explanation

At 1:50, one unit on the drawing represents 50 units on site, so 80 mm multiplied by 50 gives 4000 mm, or 4.0 m. Always convert the result to metres for ordering pipe lengths.

Question 48Reading and Interpreting Plumbing Drawings, Specifications and Standards

A drawing carries the note 'FALL 1:60'. What does this instruction require the plumber to do?

  1. Reduce the pipe diameter by 1 mm for every 60 m of run
  2. Install the pipe 60 mm below the finished floor level
  3. Lay the pipe level and fit a 60 mm vent at the end
  4. Lay the pipe so it drops 1 unit vertically for every 60 units horizontally Correct answer.

Explanation

A fall expressed as a ratio gives the vertical drop per unit of horizontal run, so 1:60 means 1 mm down for every 60 mm along. This gradient keeps drainage flowing by gravity without letting solids settle.

Question 49Reading and Interpreting Plumbing Drawings, Specifications and Standards

A drawing shows a symbol of a circle with a diagonal cross placed on a branch drain. What does this symbol normally represent?

  1. A gate valve
  2. A water meter
  3. A floor drain or gully trap Correct answer.
  4. A clean-out access point

Explanation

A circle with a diagonal cross is the conventional symbol for a floor drain or gully, which receives surface water and connects to the drainage system through a trap. The trap seal prevents sewer gases from entering the space.

Question 50Reading and Interpreting Plumbing Drawings, Specifications and Standards

A sanitary schedule lists a WC outlet as '100 mm dia., 1:40 fall'. Why must this fall be verified against the drawing before setting out?

  1. The fall only affects the colour of the pipe to be ordered
  2. The fall can be increased freely on site to save pipe
  3. The gradient must match the approved design so the drain self-cleans without scouring Correct answer.
  4. The fall determines the water pressure at the tap outlets

Explanation

Drainage gradients are designed to give self-cleansing velocity while avoiding excessive scour, and the schedule gradient must agree with the drawing. If the drawing and schedule conflict, the plumber should raise a query rather than choose arbitrarily.