CIT common mistakes
CIT · Understand the traps and how to avoid them.
Choosing lateral and main pipe sizes by rule of thumb or by matching the existing service line instead of calculating velocity and friction loss at the design flow.
Candidates memorize pipe-size tables but skip the hydraulic calculation when the exam gives flow, length, and fittings, so they cannot see when velocity or friction loss exceeds acceptable limits.
What to do instead
Convert the design flow to GPM, calculate velocity for each pipe segment, keep laterals near or below about 5 ft/s, sum friction loss through pipe, fittings, valves, and devices, and compare the total to available dynamic pressure at the point of connection.
Using static pressure at the meter or tap as the design pressure at the farthest head.
Static pressure is easy to read and candidates forget that flow, elevation, and device losses reduce pressure along the system.
What to do instead
Start with dynamic pressure at the point of connection, subtract elevation change at about 0.433 psi per foot of rise, subtract friction and device losses, and verify the remaining pressure meets the minimum operating pressure of the selected heads.
Installing an atmospheric vacuum breaker on a zone that has a downstream shutoff valve or is under continuous pressure.
Candidates memorize the names of backflow devices but not the installation limits that make each device legal, so they treat AVBs as a generic cheap option.
What to do instead
Use an AVB only on a non-continuous-pressure application with no downstream shutoff or obstruction; where continuous pressure or a downstream valve exists, specify a PVB or RPZ as allowed by the local authority.
Mounting a pressure vacuum breaker below the highest downstream sprinkler or in a below-grade vault.
Candidates confuse PVB and RPZ installation requirements and assume all backflow assemblies can be placed wherever convenient.
What to do instead
Install the PVB at least 6 inches above the highest downstream outlet, keep it out of a pit or vault where it could be submerged, and provide proper drainage and access; use an RPZ where high-hazard protection and below-grade installation are necessary and approved.
Wiring several valve solenoids in series on one controller station to reduce wire runs.
Series wiring looks like a way to save conductors, but it increases resistance and reduces voltage at each solenoid.
What to do instead
Wire solenoids in parallel, with each solenoid receiving a station wire and a shared common, and confirm total solenoid current does not exceed the controller transformer VA rating.
Sizing valve control wire by run length alone without calculating voltage drop at the solenoid.
Candidates use a rough distance rule and ignore wire gauge, shared common conductors, and solenoid inrush versus holding current.
What to do instead
Calculate voltage drop using the solenoid current, conductor length including the common return, and wire resistance; compare the result to the manufacturer's minimum operating voltage and maximum recommended distance for that wire gauge.
Pairing a spray head body with a nozzle without checking operating pressure and precipitation rate, resulting in misting, fogging, and uneven coverage.
Candidates select heads by spacing and throw only, overlooking pressure regulation and matched precipitation among nozzles.
What to do instead
Use the nozzle performance chart at the actual dynamic pressure, select pressure-regulated heads where pressure exceeds the nozzle range, and verify that all nozzles on a zone have matched precipitation rates for the head spacing.
Backfilling pipe trenches with rocky excavated spoil and compacting only the top layer.
Speed and convenience lead crews to skip bedding and lift compaction, and candidates underestimate how point loads and settlement damage pipe and fittings.
What to do instead
Provide a stable, rock-free bedding layer, place select backfill around and over the pipe, compact in shallow lifts, keep spoil and equipment back from the trench edge, and maintain the specified slope and depth of cover.
Replacing a solenoid or controller before measuring voltage at the valve and resistance at the solenoid.
Troubleshooting by parts substitution is faster in the short term and candidates do not have a systematic electrical diagnostic sequence.
What to do instead
Check controller output voltage at the station and common terminals, measure solenoid resistance and compare to the manufacturer's range, inspect the diaphragm and bleed path, and only then replace the failed component.
Entering an unsupported trench to repair a lateral because the trench is shallow or will be open only briefly.
Candidates treat shallow trenches as automatically safe and forget that soil type, moisture, spoil placement, and nearby equipment loads control cave-in risk.
What to do instead
Use protective systems such as sloping, shoring, or trench boxes as required, keep spoil and equipment back from the edge, provide safe access and egress, and call the one-call utility locating service before any excavation.