Nevada A-10C Repair of Pools and Spas Contractor Examination

On a residential pool, turnover time is the period required to circulate a volume of water equal to which quantity?

• AThe filter tank volume only
• BThe spa jet circuit volume only
• CThe entire pool water capacity
• DThe skimmer throat volume only

Which three filter media types are the standard residential circulation choices tested on the A-10C outline?

• ASand, cartridge, and diatomaceous earth
• BGravel, charcoal, and paper
• CZeolite only, bag filters, and sock strainers
• DUltraviolet lamps, ozone cells, and ionizers

After a residential replaster, when should the circulation system be started?

• AOnly after the plaster has air-cured for seven dry days
• BAs soon as the pool is filled to the middle of the skimmer or specified waterline
• CAfter the first weekend of swimming
• DOnly after the heater has run for two hours

Before draining a residential pool for plaster replacement, why must a working hydrostatic relief path be confirmed?

• ATo increase filter pressure during the drain
• BTo keep the spa jets primed while the pool is empty
• CTo vent air from the heater exchanger
• DTo relieve groundwater pressure that can float or crack an empty shell

What is the primary job of a surface skimmer in a residential circulation system?

• ATo heat return water before it enters the pool
• BTo draw the surface layer of water and floating debris into the filter circuit
• CTo replace the main-drain hydrostatic valve
• DTo inject muriatic acid into the deep end

Compared with a typical residential swimming pool, a residential spa circulation system is sized for which turnover?

• AA much longer turnover because spa water is hotter
• BThe same eight-to-ten-hour turnover used for large diving pools
• CNo turnover, because spas rely only on jet pumps
• DA much shorter turnover, commonly about 30 minutes

Which pair of values is required to calculate turnover time in hours?

• APool surface area and coping width
• BPool volume in gallons and circulation flow in gallons per minute
• CFilter tank diameter and sand mesh size only
• DHeater BTU rating and gas-line size

Why is the filter commonly run continuously for the first several days after a residential plaster replacement?

• ATo bake the plaster dry with pump heat
• BTo keep plaster dust suspended and captured instead of settling as scale or stain
• CTo empty the pool through the backwash line
• DTo satisfy a commercial four-hour public-pool turnover that A-10C work must meet

A 18,000-gallon residential pool is circulating at 50 gpm. What is the turnover time?

• A3.0 hours
• B6.0 hours
• C8.0 hours
• D12.0 hours

During plaster start-up, when should a residential sand filter typically be backwashed?

• AWhenever the pressure gauge has risen about 8 to 10 psi above the clean starting pressure
• BOnce a year on the anniversary of the plaster date
• COnly when the spa jets feel weak
• DEvery hour, whether pressure has changed or not

Which residential filter type typically captures the finest particles when it is properly coated and sized?

• AHigh-rate sand
• BCartridge
• CDiatomaceous earth
• DHair-and-lint strainer only

Why should a newly plastered residential pool be filled in one continuous operation?

• AStopping the fill can leave a bathtub ring or hydration stain at the waterline pause
• BCodes require the fill hose to run for exactly 24 hours
• CA paused fill is the only way to set waterline tile
• DContinuous filling replaces the need for a hydrostatic valve

NPC start-up practice commonly removes floor-return heads and directional eyeballs for the first days after plaster. Why?

• ATo increase heater flow through a bypass
• BTo prevent a hard jet from etching or streaking the fresh, still-hydrating finish
• CTo convert the system to a commercial gutter overflow
• DTo satisfy A-10E lighting and timer requirements

When may the pool heater be turned on after a residential plaster replacement?

• AAs soon as the fill hose is placed in the deep end
• BAfter 30 minutes of jet operation
• COnly after plaster dust is gone from the water
• DImmediately, to speed cement hydration

A practical field check that residential circulation and filtration are working after a plaster start-up is that:

• AThe main-drain cover remains visible from the deck through the water
• BThe pump strainer basket is always empty
• CThe filter pressure never changes from the clean reading
• DThe waterline tile stays completely dry

Why do return-inlet direction and dead spots matter on a newly plastered residential pool?

• ADead spots let plaster dust and unbalanced water sit, causing mottling or staining
• BDead spots are required so the deep end can air-cure
• CReturns are only decorative on A-10C projects
• DDead spots increase hydrostatic relief under the shell

After a plaster start-up in drought-conscious Southern Nevada, which filter type avoids a large backwash-to-waste dump when it loads with plaster dust?

• AHigh-rate sand, because it never needs cleaning
• BCartridge, which is removed and rinsed rather than backwashed to waste
• CDE, because spent media may be washed into the street
• DAny filter, because Clark County requires plaster dust to go to the gutter

When fittings are plugged for a drain-and-plaster job, what must be true of suction-outlet covers before the pool is returned to service?

• AAny decorative grate is acceptable if it matches the plaster color
• BCovers may be left off so the new plaster can breathe
• CListed suction-outlet covers must be reinstalled complete, secure, and tool-removable only
• DA single unprotected main drain is preferred because it increases turnover

The day after a residential replaster, the sand-filter gauge has climbed 12 psi above the clean reading and flow has dropped. What is the most likely cause?

• AThe hydrostatic valve is stuck open
• BThe bond beam has settled
• CThe gas heater thermocouple has failed
• DPlaster dust has loaded the filter media

When replacing plaster at the waterline, the finish must be detailed so that:

• APlaster is packed into the skimmer throat until the weir cannot swing
• BThe operating waterline sits at mid-skimmer and the weir remains free to float
• CThe waterline is set 6 inches below the skimmer to hide the tile
• DAll skimmers are abandoned and replaced with a garden hose

Before plaster is applied, suction outlets and return inlets are plugged. Which statement is correct?

• ASuction and return fittings may be left open so plaster can enter the pipes as extra rein…
• BOnly returns need plugs because suction lines are self-cleaning
• CEach fitting must be plugged so plaster does not enter the piping, then reopened and cove…
• DPlugs are left in permanently to increase turnover

What minimum circulation flow is required to turn over a 24,000-gallon residential pool in 8 hours?

• A25 gpm
• B40 gpm
• C50 gpm
• D80 gpm

Why do CPO hydraulics teach that one turnover does not equal 100 percent filtered water?

• ABecause filtered water remixes with unfiltered water, so about four turnovers are needed…
• BBecause sand filters refuse to run more than 15 minutes
• CBecause turnover is measured only at the spa jets
• DBecause USPSHTC 2018 prohibits more than one turnover per day

NSF/CPO filter-media rates used to check whether an existing residential filter can carry start-up flow are closest to which set?

• AHigh-rate sand 15–20 gpm/ft², DE about 2 gpm/ft², cartridge about 0.375 gpm/ft²
• BSand 0.1 gpm/ft², DE 20 gpm/ft², cartridge 15 gpm/ft²
• CAll three media at 50 gpm/ft²
• DSand 100 gpm/ft², with DE and cartridge unregulated

A newly plastered residential pool shows a stubborn stained corner opposite the returns even though the filter is clean. The most likely circulation-related cause is:

• AA dead spot where water is not being turned over
• BToo much cyanuric acid in the bond coat
• CA missing deck isolation joint
• DThe A-10C license requiring commercial gutter conversion

What pH range is the standard target for a residential pool after plaster start-up?

• A5.0 to 5.6
• B6.0 to 6.4
• C7.2 to 7.8
• D8.8 to 9.4

Total alkalinity is maintained primarily because it:

• AReplaces the need for a filter
• BMeasures only calcium hardness
• CSanitizes the water in place of chlorine
• DBuffers the water so pH does not swing

During the first week after a residential plaster replacement, how often does NPC start-up tell the contractor or owner to brush the entire surface?

• AOnce a month
• BOnly if algae is visible
• CAt least twice daily
• DNever; brushing scratches new plaster

NPC recommended start-up says not to add chlorine for how long after a new plaster fill?

• A15 minutes
• B48 hours
• C28 days
• DOne year

When adding muriatic acid during plaster start-up, the safe practice is to:

• APour acid into a dry plaster hopper
• BAdd a chemical to water, never water to the concentrated chemical
• CDump full-strength acid on the steps so it etches evenly
• DMix acid and chlorine in the same bucket to save trips

Water that is under-saturated (aggressive) after a plaster job typically does which damage?

• ADeposits a thick calcium scale that protects the finish
• BHas no effect on cementitious finishes
• CEtches plaster by dissolving calcium from the surface
• DRaises the spa temperature above 104°F

NAC 444.476 sets water chemistry for Nevada public spas. A-10C covers repair of both pools and spas, so which total-alkalinity band does that rule state?

• A10 to 20 ppm, never above 30 ppm
• B80 to 120 ppm, and alkalinity must not exceed 150 ppm
• C400 to 600 ppm
• D1,000 ppm minimum

Per NPC start-up, when should calcium hardness first be raised, and to what minimum?

• AOn fill day, dump 50 lb of dry calcium chloride on the steps
• BNever; plaster supplies all the calcium the pool will ever need
• COn day 4, slowly, to a minimum of about 200 ppm
• DAfter one year, to 1,000 ppm

After the first start-up days, NPC tells the contractor to begin cyanuric acid in which outdoor range, and NAC 444 caps CYA at what maximum?

• ANPC 30–50 ppm; NAC 444 maximum 100 ppm
• BNPC 0 ppm; NAC 444 maximum 5 ppm
• CNPC 200–300 ppm; no legal maximum
• DNPC 8–10 ppm; NAC 444 maximum 15 ppm

NAC 444 approves which method for measuring residual chlorine and rejects which older reagent?

• AApproves DPD; does not approve orthotolidine (OTO)
• BApproves OTO only; rejects DPD
• CApproves litmus paper only
• DApproves smell-and-guess

Soft fill water with very low calcium hardness is a risk to new plaster because it:

• ALeaches calcium from the finish and leaves a soft, etched surface
• BAutomatically balances the Langelier index
• CPrevents the need for brushing
• DHardens plaster faster than saturated water

High pH together with high calcium hardness on a brand-new plaster surface most often produces:

• AA glass-smooth etched finish
• BCalcium scale and cloudy water
• CA drop in spa temperature
• DImmediate hydrostatic uplift

Why are automatic pool cleaners left off during plaster start-up?

• AThey are illegal on all Nevada residential pools
• BThey can scar the still-soft finish and trap debris against the plaster
• CThey raise cyanuric acid above 100 ppm by themselves
• DNPC requires them to run 24 hours a day

If fill water or Southern Nevada source water tests high in metals, what start-up chemical is used to reduce staining of new plaster?

• AA sequestering or chelating agent
• BExtra dry chlorine dumped on the shallow end
• CUndiluted muriatic acid on the waterline
• DCopper algaecide as the first fill-day dose

High total alkalinity on start-up day is lowered with prediluted muriatic acid. What is the correct sequence after the dose?

• AShut the pump off for 24 hours so the acid can sink
• BBrush the entire surface and keep circulating so the acid does not sit in one spot
• CAdd chlorine immediately in the same bucket
• DTurn the heater to maximum to drive off carbon dioxide

What is the maximum water temperature commonly allowed for a residential spa?

• A90°F
• B98°F
• C104°F
• D120°F

The Langelier Saturation Index used to protect new plaster is built from which factor set?

• ApH, temperature, calcium hardness, total alkalinity, and TDS (with CYA correction as requ…
• BFree chlorine and cyanuric acid only
• CFilter pressure and pump horsepower only
• DCoping width and deck slope only

Widespread mottling that appears during the first weeks after a residential plaster job is most often blamed on:

• AA missing commercial gutter
• BUneven hydration, poor start-up chemistry, or inconsistent troweling
• CAn isolation joint that is too flexible
• DCalling 811 before the drain

Raised calcium nodules on new plaster are most often associated with which condition?

• AUnhydrated or poorly compacted plaster that later weeps calcium to the surface
• BA cartridge filter that was rinsed on the lawn
• CA deck coating that is too light in color
• DA spa temperature held at 98°F

A homeowner reports hairline map cracks in 10-year-old plaster but the shell does not leak. What is the usual maintenance interpretation?

• AThe pool must be abandoned
• BThose are typically check (shrinkage) cracks in the finish, not a structural shell failure
• CThe skimmer weir has failed
• DNAC 624 requires an immediate commercial conversion

NAC 624.150 limits A-10C Repair of Pools and Spas to which residential scope?

• AConstruction of commercial fountains, waterfalls, and ponds
• BInstallation of new heaters, timers, controls, and wet-niche lights
• CRepair and replacement of plaster, coping, and coating of pool decks
• DNew water and gas service lines from the meter to the equipment pad

Traditional white pool plaster is a mixture of which two primary ingredients?

• AAsphalt and silica sand
• BPortland cement and marble or similar aggregate
• CEpoxy resin and rubber crumbs only
• DGypsum plaster and wood fiber