Emergency stop device; a pull-cord runs the length of the conveyor and drops the line when pulled from anywhere along itIn: Conveyor system installation
Installed quantity times the budgeted hours per unit, the credit the estimate gives for work in place; also percent complete times budgeted hoursIn: Construction labor productivity tracking
Earned revenue
Percent complete times the revised contract value; what you have earned regardless of what you billedIn: WIP report and over/under billing
An engineered structure that holds back soil for a deep excavation and limits ground movement, distinct from an OSHA trench protective system that protects the worker.In: Excavation shoring field guide
Earthwork / grading
Moving and shaping soil to bring a site to the design elevations and slopesIn: Site grading and earthwork
East-west / north-south
Server-to-server traffic inside the data center versus traffic in and out of the buildingIn: Spine-leaf network architecture
EATR
Exhaust air transfer ratio, the percent of exhaust air carried back into the supply streamIn: ERV commissioning field guide
Equal-cost multi-path routing, which hashes flows across parallel paths and can overload one link when large flows collide on the same pathIn: Network observability for the AI fabric
The distance from the compression face to the tension steel, what gives the section its strengthIn: Rebar pre-pour inspection
Effective ground-fault current path
The intentionally constructed, low-impedance bonded metal route fault current takes back to the sourceIn: Grounding vs bonding explained
Effective ground-fault path
The permanent, low-impedance path required by 250.4 that carries fault current back to the source to trip the deviceIn: EGC sizing (NEC 250.122)
Effectiveness
The ratio of energy actually transferred to the maximum possible, reported as sensible, latent, or total percentIn: ERV commissioning field guide
Efficacy (lm/W)
Lumens of light produced per watt of power, the measure that drives the energy savingsIn: LED lighting retrofit
Effluent filter
Screened cartridge in the tank outlet that catches fine solids before they reach and clog the field; cleaned on a scheduleIn: Septic system field guide
Electric field vector mapping, an electronic leak detection method that pinpoints a membrane breach, usable through overburdenIn: Green roof installation
Exterior insulation and finish system: foam board, base coat, mesh, and a thin synthetic finishIn: Stucco and EIFS
Elastomeric / urethane membrane
A flexible, usually polyurethane, liquid-applied coating that cures to a continuous waterproof film with enough elongation to bridge cracksIn: Traffic deck coating
Elastomeric coating
Silicone, acrylic, or polyurethane top layer applied in dry mils for UV and weather protectionIn: SPF roof field guide
Elbow (ell)
A change of direction, drawn as a bend; the angle (90, 45, eighth bend) is noted or implied by the axesIn: Plumbing isometric reading guide
ELD
Electronic leak detection, locating a membrane breach by the electrical current that flows through it to a grounded conductive substrateIn: Electronic leak detection
Electric shock drowning (ESD)
Drowning caused when AC leakage into the water paralyzes a swimmer's muscles so they cannot swim; the deadly hazard at powered docksIn: Boat dock and marina construction
Electric sign
A self-illuminated display fed by building power, generally a UL 48 listed assembly installed under NEC Article 600In: Electric sign installation
Electric stress field
The electric field through the cable insulation between the conductor and the grounded shield, intense enough to need control at any cut endIn: MV termination and splicing
Electric strike vs maglock
A strike releases a latch and is usually fail-secure with mechanical free egress; a maglock holds by magnet, is fail-safe, and needs separate egress releaseIn: Access control system field guide
Electrically safe work condition (ESWC)
A state where a circuit is de-energized, locked and tagged, tested to verify the absence of voltage, and grounded where requiredIn: Lockout/tagout field guide
Electronic leak detection (ELD)
Locating a membrane breach electrically, including under overburdenIn: Roof leak diagnosis
Electronic leak detection / EFVM
A method that runs a current to pinpoint a membrane breach to within inches, usable through media and ballast without removing the overburdenIn: Green roof maintenance program
Elevator modernization
Planned replacement of an aging car's worn systems, mainly the controller, drive, and door operator, to restore reliability, ride, and code complianceIn: Elevator modernization and maintenance
Elongation
The measured stretch of the strand under load, the independent proof the design force went inIn: PT slab stressing
Embed plate
Steel plate cast into a member, anchored by headed studs, that field connections weld or bolt toIn: Precast erection and connections
Temporary securing of wall openings with exterior-grade plywood or OSB to keep weather and intruders out after a lossIn: Emergency board-up and tarping
Emergency floor drain
A floor drain placed for an occasional spill or washdown that gets little regular water and is prone to a dry trapIn: Trap primer field guide
Emergency spillway
The armored overflow path that safely passes the storm bigger than the outlet can handle, protecting the embankment from overtoppingIn: Detention and retention ponds
Emergency system (NEC 700)
Backup for code-mandated life-safety loads; the strictest class, with the fast transfer, the wiring independence, and selective coordinationIn: Emergency and standby power systems
Electromagnetic and radio-frequency interference, the electrical noise an isolated ground aims to keep off the ground pathIn: Isolated ground receptacles
Emissivity
The fraction of energy a surface radiates compared to a perfect emitter, 0 to 1; bare metal is low, painted or oxidized surfaces are highIn: Infrared thermography field guide
The point where the asphalt separates from the water in the emulsion and the surface turns from brown to black before it curesIn: Fog seal and rejuvenator preservation
A closed-cell foam core sealed in a polyethylene shell, which stays buoyant if punctured and does not shed foam; bare foam is restrictedIn: Boat dock and marina construction
Encapsulation
A coating applied to a cleaned, dried surface after remediation, never a substitute for removalIn: Mold remediation field guide
A base-mounted pump with axial suction and top discharge through a single impeller; the common mid-size hydronic pumpIn: Hydronic pump install field guide
Energy audit
A systematic study of where a building wastes energy and money, ending in energy conservation measures ranked by payback.In: Energy audit and management field guide
The share of a data center's energy reused outside the facility, higher is better; relates to PUE via ERE = (1 minus ERF) times PUEIn: Data center waste heat reuse
Energy-reducing maintenance switch (NEC 240.87)
A means to put a breaker into no-intentional-delay mode during work so the arc clears fast, resolving the conflict between coordination delay and arc-flash energyIn: Coordination study field guide
Engineering control
Source control at the tool: water to the cut, or a tool-mounted shroud on a HEPA dust collector, run ahead of any respiratorIn: Silica dust control methods
Engineering control (water vs vacuum)
Source control by wetting the cut (water) or capturing dust with a tool-mounted HEPA collector (vacuum), ahead of any respiratorIn: Silica exposure control program
Engineering survey
The OSHA Subpart T assessment of the structure's condition and unplanned-collapse risk by a competent person before demolition, kept in writing.In: Building demolition planning
Entanglement / protrusion
A projection that catches clothing or a drawstring; controlled by closing S-hooks, capping bolts, and the protrusion testIn: Playground safety surfacing
Enterprise data center
A facility an organization owns and runs for its own IT, single-tenant and owner-operatedIn: Data center types field guide
The share of the total energy difference between exhaust and outdoor air that the recovery device transfersIn: DOAS field guide
Entitlement / zoning
The land-use approvals that allow a data center on a parcel, by right or by special exception, granted by the jurisdictionIn: Data center site selection
Deliberate microscopic air bubbles that give freezing water room to expand, for in-service freeze-thaw durabilityIn: Air entrainmentCold weather concreting
The contracted, prioritized response to a passenger trapped in a stalled car, performed by the qualified mechanic, not building staffIn: Elevator modernization and maintenance
Accidental large voids from mixing and placing that do not aid durability and are removed by vibrationIn: Air entrainment
Entrapped vs entrained air
Entrapped air is the unwanted voids consolidation removes; entrained air is the deliberate bubbles for freeze-thaw that it must not destroyIn: Placement and consolidation
Entry point / breach
Where water actually crosses the membrane, often uphill of and away from the interior stainIn: Roof leak diagnosis
Environmental sensor
A device measuring site conditions such as temperature, humidity, concrete maturity, silica dust, noise, or waterIn: Connected jobsite and RTLS
EOP
Emergency operating procedure, the response procedure for an abnormal or failure eventIn: Data center MOP SOP EOP
A disinfectant registered with the EPA for a stated kill; dwell or contact time is how long it must stay wet on the surface to achieve itIn: Biohazard and trauma cleanup guide
Electrical power monitoring system and data center infrastructure management, the systems that log power and temperature during the testIn: Integrated systems test (IST)
EPO
Emergency power off, the manual disconnecting means that drops the IT load and its support so a responder can enter a dead roomIn: EPO testing field guide
Three-component resin, hardener, and aggregate grout for dynamic, chemical, and high-precision serviceIn: Grout types and baseplate grouting
Epoxy injection
Rigid, structural injection that welds a dormant crack back to monolithic strengthIn: Concrete crack injection
Epoxy vs cementitious terrazzo
Epoxy uses a thin bonded resin matrix; cementitious uses a thicker portland cement matrix, bonded or isolated from the slabIn: Terrazzo flooring install and polish
The residential sizing method that holds the same friction rate across every run, dropping velocity as the trunk reducesIn: Manual D duct design field guide
Machine-reported data including GPS location, engine hours, idle time, fuel, and fault codesIn: Connected jobsite and RTLS
Equipment warranty
The manufacturer's promise that the parts are free of defects for their term. Defective parts route to a manufacturer claim, often with a labor allowance. Terms vary by manufacturer.In: Warranty reserve and cost management guide
Equipotential
The condition where bonded parts sit at the same potential, so no noise, fault, or surge current is driven between themIn: Data center grounding and SRG
Building up and taking down the machine, the most dangerous phase, done by a manufacturer-trained crew to a set sequenceIn: Mast-climbing work platform safety
Erection drawings
The manufacturer's set with frame lines, part marks, bracing, connections, panel layout, and the erection sequenceIn: Metal building erection
Erection sequence / EOR
The engineered order of raising the frame to keep it stable; the engineer of record designs the structure and connections, the erection engineer the means of raising itIn: Steel erection and connections
Energy-reducing maintenance switch, a second trip setting that lowers clearing time and arc-flash energy during workIn: Selective coordination field guide
ERMS / maintenance mode
Energy-reducing maintenance switch; a worker-flipped mode that drops the instantaneous pickup for faster clearing during energized workIn: Arc energy reduction methods
Erosion control
Measures that keep soil from detaching in the first place, such as cover, mulch, seed, and blanketsIn: Erosion control and SWPPP
Wall thinning in copper from high-velocity hot water, worst at fittings and direction changesIn: Hot water recirculation loops
ERV / HRV
Energy recovery ventilator transfers heat and moisture (total energy); heat recovery ventilator transfers heat only (sensible)In: ERV commissioning field guide
ESAL
Equivalent single axle load: damage equal to one pass of a standard 18,000 lb single axle on dual tiresIn: Asphalt pavement thickness design
The rise in material and labor cost over a long schedule, priced separately from contingency and supported by a published index or actual cost.In: Contingency and risk pricing
External static pressure; TESP is the total across both sides of the air handler, return plus supply as magnitudesIn: External static pressure field guide
Stratification efficiency, the usable fraction of the tank volume, commonly 0.85 to 0.95In: Thermal energy storage tank
Ethylene glycol
The lower-viscosity glycol with better heat transfer and a lower freeze point, but toxic, so it is kept out of occupied potable-risk systemsIn: Hydronic water and glycol field guide
Energy use intensity, a building's annual energy per square foot in kBtu, compared against similar buildings to judge performance.In: Energy audit and management field guide
The cold plate or surface where the fluid boils and takes heat off the chipIn: Two-phase cooling
Evapotranspiration (ET / ETo)
Water lost from soil and plants to the air; reference ET (ETo) is the loss from a standard grass surface, the demand a controller replacesIn: Smart irrigation field guide
A physical barrier that keeps the animal off the plant: fencing, tree guards, cages, netting; the only layer that reliably holds under high pressureIn: Deer and wildlife protection
Exclusion / drop zone
The area where material can fall, the machine can swing, or a collapse can reach, kept clear of people during active demolition.In: Building demolition planning
Exclusion zone
The barricaded, cleared area behind every live tendon and the jack during stressingIn: PT slab stressing
Mechanical removal of air from a space to carry off odor, moisture, heat, or contaminants and set its pressureIn: Commercial exhaust ventilation guide
Existing conditions
The pre-existing state and damage photographed before work starts, the set that protects you from being charged for what you inheritedIn: Field photo documentation
A full gap through the structure that lets parts move apart and back, mainly for thermal and moisture movementIn: Building movement joint systems
Expansion joint / bearing
The joint that lets the deck move and the bearing the structure sits on; a leaking joint corrodes the bearing belowIn: Bridge deck construction
Expansion joint cover
The factory or field assembly of a bellows and two metal flanges that spans the curbs and flashes to the membrane on each sideIn: Roof expansion joint installation
An enclosure that contains an internal explosion and cools the escaping gas below ignition so it cannot light the outside atmosphereIn: Hazardous classified locations
Shallow media (~2 to 6 in), sedum and groundcovers, low load (~15 to 30 psf saturated), low maintenanceIn: Green roof installation
Extensive vs intensive
Extensive is shallow media and sedum with low maintenance; intensive is deep media and garden plantings with high, garden-level maintenanceIn: Green roof maintenance program
External equalizer
A line feeding coil-outlet pressure to the TXV diaphragm, needed on distributor and high-drop coilsIn: Metering devices field guide