The average force in the tendon over its length, after friction and seating lossesIn: PT slab stressing
P / w (service load)
The unfactored column load in pounds, or wall load in pounds per foot, the footing carriesIn: Foundation types and footings
P abs
Absolute pressure on the water at the suction source, in feet: atmospheric on an open system, fill pressure on a closed loopIn: Pump cavitation and NPSH field guide
P and K rating
Phosphorus and potassium reported low to optimum against a turf target, telling you whether to add themIn: Turf fertilization and soil testing
P and P bonds
Performance and payment bonds, issued together, guaranteeing completion and payment to subs and suppliersIn: Contractor insurance and bonding
The failure path from potential failure (P, first detectable) to functional failure (F); the interval between is the window to actIn: Predictive maintenance guide
P-T chart
Pressure-temperature chart for a specific refrigerant, converting a measured pressure to a saturation temperatureIn: Refrigerant charging field guide
A base trap that helps lift oil up a riser; an inverted top trap that stops oil draining back when the header is above the evaporatorIn: Refrigerant line sizing field guide
P_elev
Static head loss lifting water to the highest fixture, about 0.43 psi per foot of riseIn: Water supply pipe sizing guide
P_meter / P_bf
Pressure loss through the water meter and any backflow preventer at the design flow, from the device dataIn: Water supply pipe sizing guide
P_res
Minimum residual flowing pressure the worst fixture needs to operate, left on the budgetIn: Water supply pipe sizing guide
P_supply
Minimum daily service pressure at the source, in psi, the guaranteed low, not the peakIn: Water supply pipe sizing guide
PACE
Property Assessed Clean Energy financing, repaid through an assessment on the property tax billIn: HVAC customer financing guide
Pachometer
A cover meter that uses an electromagnetic field to find shallow rebar and measure cover; steel only, not deepIn: Concrete scanning before you drill
Pack-back
Returning the cleaned and stored contents to the finished structure, reconciled and signed offIn: Contents pack-out and inventory
Whole refrigeration circuit in one cabinet, versus an indoor unit and outdoor unit joined by a refrigerant line setIn: HVAC system types field guide
Packet loss
Packets dropped in the fabric, which forces a retransmit and stalls the synchronized collective the GPUs are waiting onIn: Network observability for the AI fabric
Packing
Braided rings squeezed around the shaft in a stuffing box; the older seal type, meant to weep a controlled dripIn: Hydronic pump install field guide
Permit authorizing individual, the trained person who surveys the area, sets the precautions and monitoring duration, and signs the permitIn: Hot work permit field guide
Panel replacement
Swapping the load center on the same service, keeping the existing amperageIn: Service and panel upgrade
Panelboard / load center
The dead-front assembly that splits a feeder into protected branch circuits; load center is the residential nameIn: Panelboard installation
PAPA
Positive air pressure attenuator, an engineered device that absorbs positive pressure transients an AAV cannot relieveIn: AAV and island vent guide
Storage that stripes files across many nodes so they serve throughput in parallel, scaling bandwidth with node countIn: AI storage tier architecture
Parallel neutral path
Neutral current riding on the grounding system because the neutral is bonded to ground in more than one place; the source of nuisance trips and shock hazardIn: Generator grounding and bonding
Parallel optics
A transceiver transmitting and receiving on multiple fibers at once, plugging into a native MPOIn: MPO/MTP polarity methods
Parallel set
One conductor of each phase, plus neutral and equipment ground, run together as one circuit's worthIn: Parallel conductors, NEC
Localized insulation breakdown at a defect that erodes the insulation before it flashes over; tested online or offlineIn: MV switchgear maintenance and testing
Partial discharge (PD)
A tiny localized discharge in a void or defect under voltage, the mechanism that erodes insulation and a key termination diagnosticIn: MV cable termination and testing
Particulate / filtration
Suspended solids in the coolant, removed by full-flow and side-stream filters rated to the cold-plate channel sizeIn: Liquid cooling loop chemistry
Cutting the highest flow rate leaving the site by storing water faster than the outlet releases it, the core job of a basinIn: Detention and retention ponds
The perc test measures how fast soil drains in minutes per inch; the soil evaluation reads texture, limiting layer, and water table to set feasibility and designIn: Septic system field guide
Perforated backing
Turf backing with drainage holes; fully permeable backing drains across the whole surface for higher flowIn: Artificial turf installation
Actual energy output divided by the energy expected from measured irradiance and rated capacity, the headline efficiency metric, referenced to IEC 61724In: Solar PV O&M field guide
Pergola
Posts and crossbeams with an open or louvered roof, for partial shade and airflow, free-standing or attachedIn: Pergola and shade structure guide
Perimeter control
Fencing, gates, and one controlled entrance that limit where the site can be entered and let you see who comes and goesIn: Jobsite security and theft prevention
Perimeter catches entry at doors and windows; interior catches movement inside with motion detectors; layered so each covers the other's missIn: Intrusion alarm field guide
Periodic inspection
The annual federal inspection of a commercial motor vehicle under 49 CFR 396.17, at least once every 12 monthsIn: Fleet maintenance program
A surface that passes water through it into a stone reservoir; porous usually means through the body (asphalt, concrete), permeable through the joints (pavers)In: Porous and permeable pavement
Permeable base / OGDL
Open-graded drainage layer under the surface that drains the whole footprint to a collector or daylightIn: Pavement subdrains and edge drains
Permeation grouting
Injecting low-viscosity grout into the pores of granular soil to bind the grains and cut permeabilityIn: Ground improvement and grouting
Permit authorizing individual (PAI)
The person under NFPA 51B who authorizes hot work, confirms the area is safe, and sets any extended monitoringIn: Fire watch and impairment
Permittivity vs transmissivity
Permittivity is water flow across the fabric; transmissivity is water flow in the plane of the fabric for drainage.In: Geotextile separation fabric
Perpetual pavement
A thick section designed so fatigue never reaches the bottom of the asphalt; renewed by resurfacingIn: Asphalt pavement thickness design
Open-graded, near-zero-fines concrete with interconnected voids that water drains through; also porous or permeable concreteIn: Pervious concrete field guide
PEX
Cross-linked polyethylene, a flexible plastic potable water tube in types a, b, and cIn: PEX, copper, and CPVC methods
Building a point cloud from many overlapping photographs, cheaper and full color, with softer geometry than lidarIn: Reality capture and scan-to-BIM
Photogrammetry / orthomosaic
Stitching overlapping aerial photos into a geometrically corrected, measurable map and a 3D model of a site or structure.In: Drone inspection field guide
Physical / gradation segregation
Separation of coarse from fine aggregate, leaving stone-rich or sand-rich areasIn: Asphalt segregation
PI (polarization index)
Ratio of the ten-minute to one-minute insulation-resistance reading; above 1.0 is the NETA floorIn: Padmount transformer energization
Pick radius
The horizontal distance from the crane's center of rotation to the load, which sets the rated capacity for that liftIn: Jobsite logistics field guide
Pickup / dropout
The voltage and frequency thresholds at which the controller accepts or rejects a sourceIn: ATS commissioning field guide
Pickup and delay
The current at which a function starts to act and the time it waits; the two settings that fit a curve between the load below and the source aboveIn: Coordination study field guide
Pickup and time delay
The ground current that triggers the trip and the deliberate wait before it actsIn: GFPE field guide
Potential-induced degradation, a voltage-driven string loss, against normal aging of roughly 0.4 to 0.5 percent per year over the module's lifeIn: Solar PV O&M field guide
PID / hunting
Proportional-integral-derivative control of modulating outputs; hunting is the oscillation of a mistuned loop around setpointIn: BMS and DDC controls commissioning
A prefabricated membrane cone that flashes a round pipe, welded or bonded at the base and clamped at the topIn: Roof penetration flashing
Pipe bursting
Replacing a pipe by pulling a bursting head through it that shatters the old pipe and pulls in new HDPEIn: Trenchless sewer repair field guide
Pipe-clamp probe
A thermocouple or thermistor strapped to a refrigerant line; accuracy and insulation from ambient air decide superheat and subcoolingIn: HVAC test instruments field guide
PIR senses a moving heat signature; dual-tech adds microwave and alarms only when both agree, which cuts false alarms from HVAC and sunIn: Intrusion alarm field guide
PIR / ultrasonic / dual-tech
Heat-motion line-of-sight, sound-echo fine motion, and both combined to cut false tripsIn: Lighting controls and dimming
Piston / cup
The molded cup that meters a piston flushometer; more tolerant of dirty water than a diaphragm.In: Flushometer flush valve types
Pitch / slope
Rise over run in inches per 12 in, written like 6:12, which sets the slope factorIn: Roof measurement and squares
A pourable sealer pocket flashed around an odd penetration and filled with sealant; the last-resort detailIn: Roof flashing types
Pitch pocket
A sealant-filled box sealing an odd-shaped penetration; the filler shrinks and needs topping on a scheduleIn: Roof maintenance program
Pitch pocket / pourable pocket
An open metal collar around an irregular penetration filled with pourable sealer; a maintenance item and last resortIn: Rooftop equipment supports and walkways
Pitless adapter
The fitting that takes water out of the casing horizontally below the frost line, replacing the old well pitIn: Water well drilling and well systems
Pitot traverse
A grid of velocity-pressure readings across a duct, averaged to get true average velocity and then airflowIn: Air balancing report field guide
Pixels per foot (ppf)
Horizontal pixels landed on each foot of the scene at the target distance; the metric that decides whether footage is usableIn: CCTV system design field guide
Placement
Getting fresh concrete into the forms and around the reinforcement near its final positionIn: Placement and consolidation
Placement temperature
The air and surface or base temperature at the time of paving; many specs require both above the minimum and risingIn: Cold-weather asphalt paving
Placing drawings
The detailer's plans and sections showing every bar set in place and tagged with its markIn: Rebar detailing and the BBS
Planarity / flatness tolerance
The allowed surface deviation under a straightedge, commonly 3 mm under 1 m and 6 mm under 4 mIn: Running track surfacing
Plant coverage
The percentage of the media surface the intended plants cover, commonly targeted near 80 to 90 percent within about two yearsIn: Green roof maintenance program
Plant factor / water budget
A plant's water use as a fraction of reference ET, used in ordinances like MWELO to cap a project's landscape waterIn: Xeriscape and drought-tolerant design
Plant health care (PHC)
A proactive program of scheduled inspection and care that keeps plants healthy by managing soil, roots, water, and nutrition, with pest control as one partIn: Plant health care (PHC)
Plant schedule
The table on a planting plan listing each plant by botanical name, size, quantity, spacing, and conditionIn: Landscape design and plant selection
A priced promise to replace plants that die within a set period, bounded by written exclusionsIn: Landscape estimating and bidding
Plaster start-up
The procedure for a new plaster or aggregate finish: a continuous fill, frequent brushing, and careful chemistry through the first days so the curing surface does not stain or etch.In: Commercial pool construction
A device connected to the water system that delivers water for use or receives waste, such as a toilet, lavatory, sink, urinal, shower, or drinking fountainIn: Fixtures and water efficiency
Plumbing rough
The main drains, returns, skimmers or gutter, and supply lines set and pressure-tested before the shell, so the shotcrete encases them in the structure.In: Commercial pool construction
Plumbing-up
Pulling the frame true with guys and come-alongs to within AISC 303 tolerance before connections are finalizedIn: Steel erection and connections
Plus or minus 7 percent
The common acceptance band for measured versus calculated elongation, per ACI 318 and PTIIn: PT slab stressing
Plus/minus 400 V
A DC bus referenced 400 V each side of a center point, 800 V rail to rail, which lowers the touch voltage to either railIn: Rack DC power distribution (HVDC)
Ply / ply felt
A reinforcing sheet of organic or fiberglass felt; the layers built up into the membraneIn: Built-up roof installation
PM
Preventive or planned maintenance, the scheduled servicing done on an interval rather than after failureIn: Fleet maintenance program
PM / PdM
Preventive maintenance on a schedule; predictive maintenance driven by condition data and trendingIn: HVAC preventive maintenance guide
PM compliance
Percentage of scheduled PM completed on time within its window; the program's core metricIn: Data center PM program
PM program
The full scheduled and condition-based maintenance regime for the critical power and cooling plantIn: Data center PM program
Protected membrane or inverted assembly, with the insulation and ballast placed on top of the membraneIn: Ballasted roof systems
Pneumatic test
A pressure test using air or gas, allowed only when hydrostatic is impractical, because compressed gas stores far more energy and fails dangerouslyIn: Chilled water hydro test package
Verifying each physical point one at a time so the field device matches the BMS value and each output moves the right equipmentIn: BMS and DDC controls commissioning
Poisson effect
The pressure-driven shortening of HDPE that can pull an unrestrained transition joint apartIn: Thrust restraint field guide
Water standing on a low-slope roof more than 48 hours after rain in drying weather, per NRCAIn: Roof ponding water
Pondless
A feature with no standing water; it recirculates into a hidden gravel or matrix basinIn: Water feature installation
Pool circulation
Pulling the water from the main drain and skimmers through the pump, filter, and heater and back through the returns, continuouslyIn: Pool and spa mechanical systems
Popout
A conical hole with fractured aggregate at the bottom, from unsound, reactive, or frozen aggregateIn: Concrete surface defects diagnosis
Porous / permeable asphalt
Full-depth open pavement over a stone reservoir for stormwater infiltrationIn: Asphalt mix types by layer
Porous vs non-porous
Porous materials like drywall and insulation are removed; non-porous like studs, metal, and glass are cleanedIn: Mold remediation field guide
Positive displacement
Compression by trapping a fixed volume of vapor and shrinking it; recip, scroll, screw, rotaryIn: HVAC compressor types
Stressing tendons after the concrete has cured, putting the slab into compressionIn: PT slab stressing
Post-tension (PT)
Tensioned steel tendons in a slab; cutting one releases stored energy explosivelyIn: Concrete cutting and coring
Post-tension tendon
A high-strength strand stressed to load the slab in compression; cutting one releases stored energy and weakens the structureIn: Concrete scanning before you drill
Post-tension tendon corrosion
Corrosion of stressed high-strength strand in PT slabs, from lost grease or void grout, that can fail suddenly; specialty workIn: Parking structure restoration
Post-work monitoring
The period after the fire watch ends during which the area is checked for smoldering fire, set by the PAI to the riskIn: Hot work permit field guide
A metal or molded box flashed to the roof and filled with pourable sealant; the last-resort penetration detail, also called a pitch pocket or pitch panIn: Roof penetration flashing
Power budget
Transmitter power minus receiver sensitivity, the loss the optics tolerateIn: Fiber splice loss budget
Power cabinet vs dispenser
In a split architecture, the central rectifier cabinet against the stall unit with the connector and cableIn: DC fast charging station design
Power capping
A hard limit on how much a device, rack, or row can draw, enforced by throttling before the budget is exceededIn: Power capping and oversubscription
Prefabricated electrical plant: switchgear, transformer, UPS, transfer switches, and distributionIn: Modular data center deployment
Power shelf
Centralized rectifier shelf that converts facility AC to the rack DC bus, replacing per-server power supplies, usually N+1In: Rack DC power distribution (HVDC)
Power is a short hard burst (ride-through); energy is sustained output over hours (autonomy and grid services)In: Data center battery and storage types
Power-vented / Category III
A gas unit with a powered vent that pushes flue products out, often a sidewall, against positive pressureIn: Unit heater field guide
Powered anode
Impressed-current titanium rod that protects the tank without being consumedIn: Water heater maintenance
Pozzolanic reaction
The slow lime-clay reaction at high pH that forms cementitious bonds and long-term strengthIn: Subgrade stabilization
Permit-required confined space: a confined space that also holds a serious hazard such as bad air, engulfment, or entrapmentIn: Confined space entry field guide
Dry system whose valve is released by the fire alarm panel, keeping water out of the pipe until a fire is confirmedIn: Dry-pipe and pre-action trip test
An herbicide that stops weed seed before it germinates versus one that kills a weed already growingIn: Landscape IPM field guide
Pre-engineered metal building (PEMB)
A steel building system the manufacturer engineers and fabricates as a kit of rigid frames, secondary, bracing, and panels, shipped to the site to erectIn: Metal building erection
The daily living hazard plan a crew completes for the actual conditions that morning, derived from the JHA or AHAIn: Daily huddle field guide
Pre-task plan / FLRA
The crew's field-level risk assessment of today's specific work and conditions, done before the task startsIn: JHA, toolbox talks, pre-task planning
Pre-wetting
Soaking the aggregate before batching so it does not steal mix water or lose slumpIn: Lightweight concrete
Preaction system
Dry pipe with water held back until fire detection (single- or double-interlock) acts; used for sensitive contentsIn: Fire sprinkler system design guide
The air pressure on the dry side of the expansion tank, set to the cold fill pressure before the loop is filledIn: Hydronic water and glycol field guide
Precipitation rate
The depth a zone applies per hour, in inches per hour, used to set run timeIn: Sprinkler system design
The planning phase before construction, where the team prices the design, checks constructability, value-engineers, schedules, and locks the budget.In: Preconstruction field guide
Predictive maintenance (PdM)
Condition-based maintenance triggered by measured data (IR, vibration, oil, ohmic) before failureIn: Data center PM program
Predictive twin
A connected twin plus simulation that forecasts behavior and runs what-if scenariosIn: Digital twin for operations
Prefabricated vs modular
Prefabricated means built off site in a plant; modular means designed in repeatable blocks that scale by additionIn: Modular data center deployment
A vent that opens only during the discharge pressure spike so a sealed room is not damagedIn: Clean agent room integrity
Pressure switch
The safety that proves the inducer is moving air before the gas valve can openIn: Gas furnace field guide
Pressure switch (well)
The control that starts and stops a well pump at a cut-in and cut-out, commonly 40/60 psi, with the tank pre-charged just below cut-inIn: Low water pressure guide
Pressure washing
Cleaning hard, durable surfaces with high-pressure water, commonly 2,500 to 4,000 PSI, that mechanically blasts dirt offIn: Pressure and soft washing
A box with no flow sensor that commands a damper position only, so airflow rides with duct staticIn: VAV box commissioning field guide
Pressure-equalized rainscreen
A drained, vented glazing pocket that equalizes air pressure so water is not driven in, then weeps out what gets past the outer seal.In: Curtain wall and glazing
Pressure-independent
A VAV box with a flow sensor that holds its airflow setpoint regardless of upstream duct pressure changesIn: VAV box commissioning field guide
Pressure-injection injury
A high-pressure stream puncturing skin and injecting fluid into tissue, a surgical emergency that looks minor at firstIn: Pressure and soft washing
Facility water (FWS) on the building side, technology cooling system (TCS) coolant on the clean rack side, separated by the CDU heat exchangerIn: CDU commissioning
Primary air
The ducted, dehumidified ventilation air supplied to an active beam, which also drives the inductionIn: Chilled beam commissioning
Pipe systems carrying process fluids, chemicals, gases, and steam in a plant at pressure and temperature, under ASME B31.3In: Industrial process piping
Proctor / percent compaction
A lab test of maximum dry density and optimum moisture; field fill is compacted to a percentage of itIn: Site grading and earthwork
Proctor density
The lab maximum dry density a soil or aggregate compacts to; base targets are a percent of it, commonly 95In: Paver hardscape installation
Production derate
The drop in pounds per day from rated ideal conditions to the real higher air and water temperatures of the roomIn: Commercial ice machine field guide
Earned hours divided by actual hours; above 1.0 the crew beats the budget, below 1.0 it loses (confirm which way your report runs)In: Construction labor productivity tracking
The estimated job margin dropping from one WIP update to the next; an early warning a job is going badIn: WIP report and over/under billing
Prohibited practices
Methods banned on lead paint: open-flame burning, power sanding or grinding without HEPA, heat guns above about 1100 degrees F, and dry scraping or sanding beyond small areasIn: Lead-safe renovation (RRP)
State statutes setting payment and retainage release deadlines and interest for late or wrongful withholding; nearly every state has one and the details differ.In: Retainage and retention field guide
Proof of work
A photo that backs a billed item, milestone, or completed scope, answering whether the work was actually performedIn: Field photo documentation
Proof packet
The single reviewable record that proves a scope was installed, tested, and accepted: the photos, tests, checklists, punch closeout, material records, and signoffs, tied to a locationIn: Proof packet assembly
Proof roll
Driving a loaded truck over the subgrade to find soft spots by rutting, deflection, or pumpingIn: Subgrade stabilization
The located, dated photo record that follows the building into operations, the as-built and equipment set the owner runs againstIn: Field photo documentation
The low-toxicity glycol (FDA generally recognized as safe) used in occupied-building HVAC; higher viscosity, slight heat-transfer penaltyIn: Hydronic water and glycol field guide
Propylene glycol (PG)
The common glycol in the secondary loop, often near 25 percent (PG25), for freeze protection and biostatic effect at a heat-transfer penaltyIn: Liquid cooling loop chemistry
A detection system that senses when a person or object enters a zone around a machine and alerts the operator, the worker, or both. Also called a proximity detection system.In: Proximity warning and struck-by safety tech
The pressure and temperature ports on a balancing valve, read with a DP gauge for flow and a probe for water temperatureIn: Hydronic balancing field guide
PTAC
Packaged terminal air conditioner: self-contained through-wall unit with cooling and electric-strip heatIn: PTAC and PTHP field guide
Enclosure where conductors are pulled, routed, or spliced between raceways, sized by 314.28 geometryIn: Pull box sizing, 314.28
Pull planning
The trades planning backward from a milestone together, each owning its durations and handoffs, so the plan has buy-inIn: Lean construction field guide
Pull planning / Last Planner
Trades build the sequence backward from a milestone so they own itIn: Project scheduling
Piping the pump to pump away from the expansion tank so its differential pressure adds to the suction, raising NPSHaIn: Pump cavitation and NPSH field guide
Placing the pump so it pushes water away from the expansion tank, adding its head to the loop instead of subtracting itIn: Expansion tank and air field guide
A sector on a wheel that flushes carried-over exhaust before the matrix rotates into the supply streamIn: ERV commissioning field guide
Purlin / girt (secondary)
Cold-formed Z or C members that span between frames to carry the roof (purlins) and wall (girts) panels and brace the framesIn: Metal building erection
Purple pipe
The purple-colored or purple-marked piping that identifies non-potable reclaimed, rain, or graywaterIn: Graywater and rainwater harvesting
Purple pipe / Pantone 512
The reclaimed identification color, carried in pipe, tape, tags, and boxes with a do-not-drink warningIn: Reclaimed water and purple pipe
Push (resistance) pier
A steel pier driven by hydraulic ram using the building's weight as reaction, for settlement repair and liftIn: Foundation underpinning and repair
Push-pull
A fast recovery method for large liquid charges that drives liquid into the cylinder using machine-generated pressureIn: Refrigerant leak detection field guide
Pressure or atmospheric vacuum breaker; protects against back-siphonage only, not backpressureIn: Cross-connection control
PVB / SVB
Pressure vacuum breaker and its spill-resistant version, a check plus an air inlet for backsiphonage only (ASSE 1020 / 1056)In: Backflow test procedure guide
PVC
Polyvinyl chloride, a heat-weldable thermoplastic membrane, the chemical and grease resistance leaderIn: TPO vs EPDM vs PVC