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The engineer exam. Real jobs, real decisions.

Every engineer who joins 247 Rapid Response works through this exam before we put them in front of a customer. It's how we keep the bar where it is.

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Select the role you applied for. Each exam is 25 questions, 30-minute limit, 75% to pass.

Examination conditions: No external sources, no copying questions, no consulting other parties. By starting the exam you confirm you understand and accept these conditions. Your answers will be auto-marked and the result emailed to recruitment.

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Q1. Under the Water Supply (Water Fittings) Regulations 1999, what is the maximum permitted lead content of fittings used in drinking-water supply?

No restriction, lead is allowed unless the customer requests otherwise Lead is prohibited in all new fittings on potable water supply Up to 50% lead by weight Lead solder is permitted in any potable installation

Q2. Which Building Regulations Approved Document covers hot and cold water supply, sanitation and water efficiency?

Part B Part F Part G Part L

Q3. What is the minimum air gap (Type AA / AG) required at a tap discharging into a basin to prevent backflow?

The vertical distance from the lowest point of the outlet to the spillover level No air gap required if a check valve is fitted Equal to the diameter of the pipe 20mm regardless of fitting

Q4. Under WRAS Schedule 2, into which fluid category does water in a domestic toilet cistern fall?

Category 1 Category 2 Category 3 Category 5

Q5. What is the typical maximum incoming mains water pressure that a domestic combination boiler is designed to operate at?

1 bar 3 bar 10 bar No upper limit

Q6. When should a pressure-reducing valve (PRV) typically be fitted on a domestic incoming mains?

Only on commercial properties When incoming pressure exceeds approximately 5 bar Always, as standard Never, it reduces flow rate

Q7. What is the legal minimum drinking water hardness in the UK?

There is no UK minimum, water hardness is not regulated as drinking-quality criterion 20 mg/l calcium carbonate 100 mg/l calcium carbonate 250 mg/l calcium carbonate

Q8. On a vented hot water cylinder, what is the typical purpose of the cold-feed cistern?

To pre-heat cold water before reaching the cylinder To provide a constant gravity-fed water supply to the cylinder and a vent path for expansion To filter limescale Modern cylinders no longer require a cold-feed cistern

Q9. What is the minimum recommended fall on a horizontal soil pipe of 100mm diameter (Building Regs Part H)?

1:10 1:40 to 1:110 1:200 No fall required if the pipe is straight

Q10. Which colour is the band on a fully-WRAS-approved fitting label?

Red Blue Yellow Green

Q11. What is the typical operating temperature range of a domestic unvented hot water cylinder?

30,50°C 45,65°C 60,95°C 100,120°C

Q12. Under HSG274 / L8 ACoP, what is the recommended hot water storage temperature to control Legionella?

35°C 45°C Above 60°C Above 90°C

Q13. What does TMV3 stand for in plumbing?

Three-way Mixing Valve Thermostatic Mixing Valve grade 3 (healthcare standard) Total Manifold Valve Time-managed Variable valve

Q14. On a domestic combi boiler, what is the typical recommended cold-fill system pressure?

0.2 bar 1.0 to 1.5 bar 2.5 bar 4 bar

Q15. Which type of joint should NOT be used on natural gas pipework?

Compression with hemp and jointing compound Capillary soldered with low-melting-point lead solder Welded steel Approved push-fit on copper

Q16. Under Water Regulations, what colour is required for an indicator on the cold-water supply main stop valve in a non-domestic installation?

No colour required Blue Red Yellow

Q17. A property has a single 15mm cold-water supply serving 2 bathrooms. What is the most likely problem you'll diagnose?

Excess flow capacity Inadequate flow at simultaneous use Pressure too high Frozen pipe risk

Q18. What is the minimum number of isolation valves a typical washing machine connection should have?

None, supply directly One on the cold supply only One on each supply (hot and cold) plus drainage isolation Three on the cold, two on the hot

Q19. Lead pipe replacement on the public-side supply (between Thames Water main and boundary stop tap) is typically:

The owner's responsibility at full cost Funded or subsidised by Thames Water Banned in the UK Only for commercial properties

Q20. What is the standard pipework material code 'Cu' on a Bills of Quantities for plumbing?

Copper Cast iron Cement-line ductile Cu = customer-supplied

Q21. On a sealed central heating system, the function of the expansion vessel is:

To filter sludge To absorb expansion of heated water and maintain stable system pressure To control flow rate To pre-heat the water

Q22. A power flush is typically recommended at what age of central heating system without prior flushing?

Every 6 months Every 5,7 years if a magnetic filter is fitted Every 25 years Only on commercial systems

Q23. What is the minimum height a cold water cistern in a loft should be supported off the joists?

No requirement On a continuous bearer not directly on the ceiling joists 100mm above the joists Hanging from the rafters

Q24. What is the typical cause of 'water hammer' in a domestic plumbing system?

Quick-closing valves causing pressure shock waves Calcium carbonate build-up Air in the system Low system pressure

Q25. Under the Building Regulations Part G, what is the minimum number of WCs required in a domestic dwelling?

None, no minimum One Two One per bedroom

Q1. Working on natural gas in the UK requires registration with which body?

NICEIC Gas Safe Register HETAS CORGI (now defunct)

Q2. What is the commonly required ACS competency to work on domestic gas boilers?

CCN1 + CENWAT ELEC1 CSCS Gold CCN1 alone is sufficient

Q3. Under the Gas Safety (Installation and Use) Regulations 1998, what is the legal duty regarding suspected gas leaks?

Repair within 28 days Make safe by isolating the supply and notifying the responsible body without delay Test the next working day Annotate on the next CP12

Q4. What is the recommended carbon monoxide concentration limit in flue gas for a properly commissioned modern condensing boiler?

Below 100 ppm in normal operation Up to 1000 ppm is acceptable No limit specified Above 500 ppm only

Q5. What is the standard ratio used to assess combustion efficiency expressed as CO/CO₂?

Should be greater than 0.01 Should be less than 0.0040 Equal to 1 Not relevant for domestic boilers

Q6. A landlord gas safety record (CP12) must be renewed how often by law?

Every 6 months Every 12 months Every 5 years Only on tenant change

Q7. What is the minimum gas working pressure for a typical domestic natural gas appliance?

10 mbar 20 mbar (standard) 50 mbar 100 mbar

Q8. On a sealed central heating system, what pressure typically opens the pressure relief valve (PRV)?

1 bar 3 bar 6 bar 10 bar

Q9. What is a tightness test under BS 6891?

A test of pipework structural strength A standardised pressure-decay test of gas pipework A test of insulation thickness A flue gas analysis

Q10. Yellow flames on a natural gas appliance typically indicate:

Correct combustion Incomplete combustion and possible carbon monoxide production Excess oxygen Pilot light only

Q11. Under the Smoke and Carbon Monoxide Alarm (England) Regulations 2022, where must a CO alarm be fitted in a rented property?

No requirement In every room with a fixed combustion appliance (excluding gas cookers) Only in the kitchen Only in bedrooms

Q12. What is the typical primary cause of 'kettling' noises in a boiler heat exchanger?

Air in the system Limescale and sludge build-up High mains pressure Faulty fan

Q13. A condensing boiler's condensate pipe must terminate where, externally?

Into a soil stack only To an appropriate drain via an approved fall and frost-protected route Into a soakaway Into rainwater downpipe (acceptable)

Q14. What does 'Benchmark' refer to in boiler installation?

A test bench at the factory The commissioning record book that validates manufacturer warranty The benchmark price An industry training body

Q15. Under Part L of the Building Regulations, what is the minimum SEDBUK efficiency rating for a new domestic gas boiler installation?

No requirement Currently A-rated (≥92%) Minimum E-rated Minimum 70%

Q16. What is OpenTherm in the context of heating?

A type of underfloor heating A modulating boiler-control protocol allowing variable boiler output A pressure release valve A type of pump

Q17. A magnetic system filter (e.g. Adey MagnaClean) is fitted primarily to:

Reduce limescale Capture iron-oxide sludge to protect the heat exchanger Improve water taste Filter chlorine

Q18. A boiler displays Worcester error code 'EA'. This typically indicates:

Low gas pressure Flame loss / ignition failure Pump failure PCB failure

Q19. The minimum required service interval for boiler manufacturer warranty validity is typically:

Every 5 years Every 12 months Never, service is optional Every 6 months

Q20. What does an 'unvented' hot water cylinder require in addition to a sealed central heating circuit?

G3 unvented certification for the installer Extra insulation only No additional certification An open vent pipe

Q21. What is the typical inhibitor concentration recommended for a sealed central heating system (e.g. Sentinel X100)?

1% of system volume No specific quantity 2 litres regardless of system size 10 litres for any system

Q22. In a hard-water London area, what additional protection should typically be specified for a new combi boiler?

No special action Magnetic filter + system inhibitor + (in hard zones) scale reducer or softener Higher gas pressure Larger heat exchanger only

Q23. A Vaillant boiler displays error 'F22'. This typically means:

No water pressure High gas pressure Fan failure PCB failure

Q24. The diaphragm in a domestic combi expansion vessel typically fails after how many years?

1 year 5,10 years 20 years Never fails

Q25. After fitting a new boiler, what test is required before commissioning is signed off?

Visual inspection only Tightness test, gas pressure check, flue gas analysis (FGA), water pressure test Customer signature only No test required

Q1. Under Building Regulations Part H, what is the typical minimum fall on a 100mm horizontal soil pipe?

1:5 1:40 to 1:110 1:200 No fall required

Q2. What does a CCTV drain survey typically use for defect classification?

No standard WRc coding BS EN 1994 Local council standards only

Q3. The transfer of private sewers to water companies in England occurred under which legislation?

Water Industry Act 1991 Private Sewer (Adoption) Regulations 2011 Drainage Act 2000 Pipework Regulations 1998

Q4. A typical high-pressure drain jetting unit operates at what pressure?

100 PSI 1,500 to 4,000 PSI 20 bar No pressure rating

Q5. What is CIPP in drainage?

Cast Iron Pipe Profile Cured-in-Place Pipe, no-dig drain repair Compressive Internal Pressure Pipe Cement-Infused Plastic Pipe

Q6. Tree-root infiltration in clay drains is typically the result of:

Poor pipe material Failed joints providing entry points and water/nutrient access Undersized pipework No common cause

Q7. What is a typical sign of a collapsed drain in CCTV survey?

Smooth pipe Visible ovality, sagging, fractures or partial cavity in the pipe wall Limescale build-up Discoloured water

Q8. A Build-Over Agreement is required when:

Building any extension Building over or near a public sewer Building a swimming pool Always required for any new build

Q9. Sewage backup into a property is classified under industry-standard IICRC S500 as:

Category 1, clean Category 2, grey Category 3, black water (biohazard) Category 4, sterile

Q10. What is the typical lifespan of a CIPP relined drain?

1,5 years 10,20 years 50+ years Indefinite

Q11. What is the principal cause of FOG (fat-oil-grease) blockages in commercial kitchens?

Hot water Improperly maintained or absent grease traps and customer waste discharge Excess detergent No identifiable cause

Q12. Under Building Regs Part H, the minimum diameter for a domestic foul soil pipe is typically:

50mm 100mm 150mm 200mm

Q13. What is a typical sonde used for in drainage?

Measuring water hardness Locating drain runs and depth using a transmitter and detector Cleaning drains Pressure testing

Q14. A combined sewer system carries:

Only foul waste Only surface water Foul waste and surface water in one pipe Only commercial effluent

Q15. Most central London is served by:

Modern separated drainage The Victorian-era Bazalgette combined sewer network Private septic tanks No sewer system

Q16. What is the Trade Effluent Consent process?

A free service for all businesses A formal authorisation from the water company for non-domestic discharges Only required for industrial premises Never required

Q17. For a domestic property in London, the responsibility for the underground drain typically transfers to Thames Water at:

The kitchen sink The boundary of the property The road Never, it's always private

Q18. A sewer surcharge means:

The water company is increasing prices The sewer is full and overflowing back into the system A new connection is being made The pipes are being cleaned

Q19. A typical residential drain inspection chamber cover bears the marking:

No marking Indicating minimum loading capacity (e.g. A15, B125, C250) Always cast iron Always concrete

Q20. What is the typical clearance method for a drain blocked with hair and soap scum?

Acid Mechanical augering or low-pressure jetting Replacement of all pipework High explosives

Q21. Under the Water Industry Act 1991, an unauthorised discharge into a public sewer can result in:

A warning letter only Significant fines and prosecution No legal consequence Free remediation by the water company

Q22. On a CCTV survey, defect code 'JD' typically refers to:

Junction defect Joint Displaced Joint Defective Various interpretations, refer to WRc Manual of Sewer Condition Classification

Q23. Routine drain maintenance for a commercial restaurant might be scheduled at what frequency?

Once every 5 years Monthly to quarterly depending on FOG load Daily Never required

Q24. What is the typical purpose of a 'gully trap' in domestic drainage?

To collect rainwater only To provide a water-filled trap preventing sewer gas escape To filter solids To increase pressure

Q25. A property suffering recurring drain blockages despite repeat clearance most likely has:

Insufficient water pressure An underlying structural defect (collapse, root intrusion, dropped joint) Too much water usage No cause, random recurrence

Q1. What is the typical duration of a Level 2 plumbing apprenticeship in the UK?

3 months 12,24 months 5 years No defined duration

Q2. Under the Health and Safety at Work Act 1974, an employer's primary duty is to:

Ensure profitability Ensure, so far as is reasonably practicable, the health, safety and welfare of employees and others affected by their work Ensure all work is rapid Hold annual meetings

Q3. PUWER 1998 stands for:

Plumbing Universal Workshop Equipment Regulations Provision and Use of Work Equipment Regulations Pressure Under Water Equipment Regulations Plumber's Universal Worksite Emergency Rules

Q4. Under COSHH 2002, an MSDS or SDS is:

A type of pipe A Material/Safety Data Sheet outlining the hazards and safe handling of a substance A safety mask A monthly safety drill

Q5. At minimum, what PPE should be worn when soldering copper pipework?

No PPE required Safety glasses and heat-resistant gloves at minimum Full SCBA breathing apparatus Steel-toed boots only

Q6. A plumber's mate or apprentice should NOT carry out:

Holding pipework while a senior solders Carrying tools Sole responsibility for gas appliance work Cleaning the worksite

Q7. The typical minimum age to start a plumbing apprenticeship in the UK is:

12 16 21 25

Q8. In a written quote, 'POA' typically means:

Per-occasion adjustment Price On Application Plumbing Owner Approval Pre-Order Audit

Q9. A 'compression fitting' joins copper pipe by:

Heat soldering An olive crushed between nut and body to form a seal Welding Glueing

Q10. 'Backflow' in plumbing means:

Water flowing in the correct direction Reverse flow that could contaminate the supply Water heating up A type of valve

Q11. The colour of natural gas pipework in a UK installation is conventionally:

Blue Yellow Red Green

Q12. Cold-water supply pipework is conventionally coloured:

Yellow Blue Red Green

Q13. What is a 'stop tap'?

A type of dishwasher The main isolating valve for the property's water supply A toilet flush mechanism A radiator valve

Q14. A 'BSP' thread is:

A type of solder British Standard Pipe thread, UK plumbing thread standard A British Safety Plumber A type of tile

Q15. When working at height above 2 metres, the regulations that primarily apply are:

No specific regulations The Working at Height Regulations 2005 Working from Above Act 1990 Working High Up Order 2010

Q16. A 'TRV' is:

Tap Replacement Valve Thermostatic Radiator Valve Toilet Repair Valve Trade Reference Volume

Q17. Under the Manual Handling Operations Regulations 1992, an employer should:

Insist all tasks are done manually Avoid manual handling so far as reasonably practicable, assess unavoidable lifting, and reduce risk Ban manual handling completely Provide no training

Q18. Lead is no longer permitted in solder for potable (drinking) water plumbing because:

It is too expensive It is a toxic heavy metal contaminating water supplies It melts at the wrong temperature Aesthetic preference

Q19. The CSCS card is:

A drainage qualification A scheme indicating training and competence to work on construction sites in the UK A type of fitting A water meter

Q20. Apprentice attendance at college (block release / day release) typically forms part of the apprenticeship because:

It is optional It provides the structured theoretical and assessed portion of the qualification It reduces wages Apprentices need a holiday

Q21. A plumber's typical first response to a leak should be to:

Begin repair immediately without isolation Isolate the supply and assess the situation safely first Take photographs only Charge the customer extra

Q22. A first-fix plumbing stage typically refers to:

The final installation Pipework and connections installed before walls/floors are closed up Customer hand-over Annual servicing

Q23. What is the legal minimum ventilation requirement for a room containing a flueless gas appliance?

No requirement Permanent ventilation per the appliance manufacturer and Building Regulations Part J No ventilation needed Ventilation only required when in use

Q24. Why is a 'gas tightness test' important after gas pipework alteration?

It confirms no gas escape under operating pressure, required for safety It tests pipe colour It is not legally required It tests water pressure

Q25. As an apprentice, the most important attribute on the job is:

Working faster than seniors Asking questions, learning the regulations and never working beyond your competence Taking shortcuts Avoiding all manual work

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