Electrical Reference Library

Published now

• Master Guide to Building Wire TypesTHHN/THWN-2, XHHW-2, RHW-2, USE-2 and other building wire types, how the letter codes decode and where each is usedRef EL-0001
• Breaker Types & Ratings ExplainedMiniature, molded-case, insulated-case and power breakers, GFCI/AFCI, supplementary protectors and what each nameplate rating meansRef EL-0002 · Safety-critical
• Nonmetallic-Sheathed Cable (NM-B)Construction, conductor count, jacket colors by size as an industry convention, and permitted and prohibited usesRef EL-0006
• Underground Feeder Cable (UF-B)Solid-jacket direct-burial cable, how it differs from NM-B and where it is usedRef EL-0007
• Service Entrance Cable (SE, SER, SEU, USE-2)Service and feeder cable styles, aluminum vs copper, and how SER differs from SEURef EL-0008
• Metal-Clad (MC) and Armored (AC) CableInterlocked armor cable types, grounding paths, MC-AP and health-care variantsRef EL-0009
• Tray Cable (TC and TC-ER)Multiconductor tray cable, exposed-run (ER) rating and industrial usesRef EL-0010
• Flexible Cords (SJOOW, SOOW, SJTW)Portable cord families and how the jacket letters decodeRef EL-0011
• Fixture, Machine Tool and Appliance Wiring Material (TFFN, MTW, AWM)Small-gauge wire types used inside equipment, panels and fixturesRef EL-0012
• Photovoltaic (PV) Wire and USE-2 for SolarPV wire vs USE-2, sunlight resistance and DC system wiringRef EL-0014
• Aluminum Building Wire (AA-8000 Series)8000-series aluminum alloy conductors, compact stranding and termination requirementsRef EL-0015
• Copper Conductor Stranding ClassesSolid, Class B, C, K and M stranding and why fine-strand needs rated terminalsRef EL-0016
• Communications and Data Cable (Cat 5e, 6, 6A)Twisted-pair categories, CM/CMR/CMP ratings and shielded vs unshieldedRef EL-0017
• Control and Instrumentation Cable (PLTC, ITC)Power-limited tray cable and instrumentation tray cable for controlsRef EL-0019
• Electrical Metallic Tubing (EMT)Thin-wall steel and aluminum tubing, fittings and where it can be usedRef EL-0020
• Rigid Metal Conduit (RMC) and Intermediate Metal Conduit (IMC)Threaded heavy-wall conduits, galvanized steel, aluminum and stainless optionsRef EL-0021
• PVC Conduit (Schedule 40 and 80)Rigid nonmetallic conduit types, expansion fittings and physical-damage locationsRef EL-0022
• Flexible Conduit (FMC, LFMC, LFNC)Flexible metal and liquidtight conduit types and their grounding limitationsRef EL-0023
• Wire Gauge (AWG) Size & Dimension ChartAWG and kcmil sizes with solid-conductor diameters and cross-sectional areasRef EL-0048
• Electrical Wire Color CodesCode-required identification for grounded and grounding conductors, common conventions for ungrounded conductors, and international colorsRef EL-0049
• Common Electrical Symbols ChartOne-line and schematic symbols used on drawingsRef EL-0060
• Electrical Formulas Wall ChartOhm's law, power and single- and three-phase current formulasRef EL-0063
• Twist-On Connector Range GuideHow to read manufacturer combination charts for twist-on connectorsRef EL-0065
• How to Identify Conduit TypesField identification of EMT, IMC, RMC, PVC, ENT and flexible conduits by wall, threads, markings and fittingsRef EL-0066

Technical Reference

Wire and cable types, raceways, overcurrent devices, wiring devices and distribution equipment, with the code articles that govern them.

• Master Guide to Building Wire TypesTHHN/THWN-2, XHHW-2, RHW-2, USE-2 and other building wire types, how the letter codes decode and where each is usedRef EL-0001
• Breaker Types & Ratings ExplainedMiniature, molded-case, insulated-case and power breakers, GFCI/AFCI, supplementary protectors and what each nameplate rating meansRef EL-0002 · Safety-critical
• Conductor Ampacity: How to Read the NEC TablesHow ampacity tables, temperature columns, correction and adjustment factors work, pointing to the governing tables (no values)Coming soon
• Overcurrent Protection Sizing BasicsConductor protection, the next-size-up rule and small-conductor limits explained in plain terms, with code referencesComing soon
• Terminal Temperature Ratings (60/75/90 °C)Why the lowest-rated termination in the circuit limits the usable conductor ampacityComing soon
• Nonmetallic-Sheathed Cable (NM-B)Construction, conductor count, jacket colors by size as an industry convention, and permitted and prohibited usesRef EL-0006
• Underground Feeder Cable (UF-B)Solid-jacket direct-burial cable, how it differs from NM-B and where it is usedRef EL-0007
• Service Entrance Cable (SE, SER, SEU, USE-2)Service and feeder cable styles, aluminum vs copper, and how SER differs from SEURef EL-0008
• Metal-Clad (MC) and Armored (AC) CableInterlocked armor cable types, grounding paths, MC-AP and health-care variantsRef EL-0009
• Tray Cable (TC and TC-ER)Multiconductor tray cable, exposed-run (ER) rating and industrial usesRef EL-0010
• Flexible Cords (SJOOW, SOOW, SJTW)Portable cord families and how the jacket letters decodeRef EL-0011
• Fixture, Machine Tool and Appliance Wiring Material (TFFN, MTW, AWM)Small-gauge wire types used inside equipment, panels and fixturesRef EL-0012
• Medium-Voltage Power Cable (MV-90, MV-105)Shielded MV cable construction, insulation levels and terminations at a distributor levelComing soon
• Photovoltaic (PV) Wire and USE-2 for SolarPV wire vs USE-2, sunlight resistance and DC system wiringRef EL-0014
• Aluminum Building Wire (AA-8000 Series)8000-series aluminum alloy conductors, compact stranding and termination requirementsRef EL-0015
• Copper Conductor Stranding ClassesSolid, Class B, C, K and M stranding and why fine-strand needs rated terminalsRef EL-0016
• Communications and Data Cable (Cat 5e, 6, 6A)Twisted-pair categories, CM/CMR/CMP ratings and shielded vs unshieldedRef EL-0017
• Fire Alarm and Power-Limited Cable (FPL, FPLR, FPLP)Fire alarm cable types, ratings and where circuit integrity cable is required insteadComing soon
• Control and Instrumentation Cable (PLTC, ITC)Power-limited tray cable and instrumentation tray cable for controlsRef EL-0019
• Electrical Metallic Tubing (EMT)Thin-wall steel and aluminum tubing, fittings and where it can be usedRef EL-0020
• Rigid Metal Conduit (RMC) and Intermediate Metal Conduit (IMC)Threaded heavy-wall conduits, galvanized steel, aluminum and stainless optionsRef EL-0021
• PVC Conduit (Schedule 40 and 80)Rigid nonmetallic conduit types, expansion fittings and physical-damage locationsRef EL-0022
• Flexible Conduit (FMC, LFMC, LFNC)Flexible metal and liquidtight conduit types and their grounding limitationsRef EL-0023
• Electrical Nonmetallic Tubing (ENT)Corrugated nonmetallic tubing and where it is permittedComing soon
• Conduit Fittings (Set-Screw, Compression, Threaded)Fitting styles, concrete-tight and raintight ratings and when each is requiredComing soon
• Outlet and Device BoxesMetallic and nonmetallic boxes, mud rings, extension rings and listingsComing soon
• Box Fill Calculations ExplainedHow box volume and conductor allowances work, pointing to the code tablesComing soon
• Conduit Fill: How to Use NEC Chapter 9How conductor areas, fill percentages and Annex C tables are used togetherComing soon
• Wire Connectors (Twist-On, Push-In, Lever, Split-Bolt)Connector types, listings and the wire combinations they are rated forComing soon
• Compression Lugs and TerminalsLug types, barrel styles, die codes and CU/AL ratingsComing soon
• Grounding and Bonding HardwareGround clamps, bonding bushings, jumpers and listed connectorsComing soon
• Ground Rods and Grounding ElectrodesElectrode types, rod materials and the code rules that govern installationComing soon
• Fuse Classes (J, RK1, RK5, T, CC, L)UL fuse classes, rejection features, time-delay vs fast-actingComing soon
• Panelboards and Load CentersMain breaker vs main lug, bus ratings, plug-on vs bolt-on and listingsComing soon
• Safety Switches (General Duty vs Heavy Duty)Fusible and non-fusible disconnects, enclosure types and duty classesComing soon
• Receptacle Types and NEMA ConfigurationsStraight-blade and locking configurations, grades and tamper/weather resistanceComing soon
• GFCI and AFCI DevicesReceptacle and breaker types, where required and dual-function optionsComing soon
• Surge Protective Devices (SPD Types 1-4)SPD types, locations and nameplate ratingsComing soon
• Dry-Type TransformersConstruction, taps, K-factor and efficiency regulationComing soon
• Motor Starters, Contactors and Overload RelaysStarter types, IEC vs NEMA sizing and overload classesComing soon
• Motor Nameplate Data ExplainedHorsepower, FLA, service factor, frame, enclosure and code letterComing soon
• Enclosure Types: NEMA vs IP RatingsNEMA type numbers vs IP codes and why they are not directly interchangeableComing soon
• Cable Tray Types and SelectionLadder, ventilated trough, solid-bottom and wire-basket trayComing soon
• Strut Channel and Support HardwareStrut profiles, fittings, finishes and conduit supportsComing soon
• Hazardous Locations: Classes, Divisions and ZonesClass/Division vs Zone systems and what distributors must ask before quotingComing soon
• EV Charging Equipment BasicsLevel 1/2 and DC fast charging, receptacles vs hardwired EVSEComing soon
• Luminaires and LED Retrofit KitsFixture listings, retrofit kit classification and Type A/B/C LED lampsComing soon

Wall Charts

Printable one-page shop and counter charts for quick lookup.

• Wire Gauge (AWG) Size & Dimension ChartAWG and kcmil sizes with solid-conductor diameters and cross-sectional areasRef EL-0048
• Electrical Wire Color CodesCode-required identification for grounded and grounding conductors, common conventions for ungrounded conductors, and international colorsRef EL-0049
• AWG to Metric (mm²) Conversion ChartNearest metric conductor sizes to AWG and kcmil sizesComing soon
• Conduit Trade Size and Metric Designator ChartTrade sizes and their metric designatorsComing soon
• NEMA Receptacle Configuration ChartFace diagrams of common straight-blade and locking configurationsComing soon
• NEMA Enclosure Type ChartWhat each NEMA enclosure type protects againstComing soon
• IP Code ChartFirst and second digit meanings in IP ratingsComing soon
• Flexible Cord Letter-Code DecoderWhat S, J, E, O, OO, T, W and other cord letters meanComing soon
• Building Wire Letter-Code DecoderWhat T, H, HH, W, N, X, R, U and -2 meanComing soon
• Fuse Class Comparison ChartFuse classes side by side with rejection features and typical applicationsComing soon
• Breaker Trip Curve BasicsHow to read time-current curves and the meaning of B, C, D and K curvesComing soon
• Hazardous Location Marking DecoderHow to read Class/Division and Zone equipment markingsComing soon
• Common Electrical Symbols ChartOne-line and schematic symbols used on drawingsRef EL-0060
• Motor Full-Load Current: Where to Find ItWhich NEC tables to use for motor FLC and why nameplate FLA is differentComing soon
• Arc-Flash Label AnatomyWhat each field on an arc-flash warning label meansComing soon
• Electrical Formulas Wall ChartOhm's law, power and single- and three-phase current formulasRef EL-0063
• Lockout/Tagout Steps ChartThe sequence of an energy-control procedure for electrical workComing soon
• Twist-On Connector Range GuideHow to read manufacturer combination charts for twist-on connectorsRef EL-0065

Measure & Identify

How to identify, measure and match electrical products at the counter and in the field.

• How to Identify Conduit TypesField identification of EMT, IMC, RMC, PVC, ENT and flexible conduits by wall, threads, markings and fittingsRef EL-0066
• How to Read a Building Wire Print LegendDecoding the surface printing on wire and cableComing soon
• How to Measure Wire Gauge in the FieldUsing a wire gauge, calipers and stripping tool marks, and the stranded-wire trapComing soon
• How to Identify Solid, Stranded and Compact ConductorsVisual identification and why it matters for terminationsComing soon
• How to Identify Copper, Aluminum and Copper-Clad AluminumColor, scratch test, markings and termination implicationsComing soon
• How to Identify a Breaker for ReplacementBrand, type, frame, poles, rating and listed/classified replacementsComing soon
• How to Read a Breaker LabelLocating ampere, voltage, interrupting rating, HACR/SWD and wire rangeComing soon
• How to Identify Fuse Class from the LabelReading class, voltage, interrupting rating and time-delay markingsComing soon
• How to Identify a NEMA Plug or ReceptacleMatching blade shape, ground pin and locking style to a configurationComing soon
• How to Measure Conduit Trade SizeWhy trade size is not the measured diameter and how to confirm itComing soon
• How to Identify Conduit FittingsTelling set-screw, compression, threaded and liquidtight fittings apartComing soon
• How to Identify Box Types and VolumesFinding marked volume and identifying box styleComing soon
• How to Read a Motor NameplateField-by-field reading of a NEMA motor nameplateComing soon
• How to Read a Transformer NameplatekVA, primary/secondary voltages, taps, impedance and connection diagramsComing soon
• How to Identify Cord Type from Jacket PrintReading and verifying cord markingsComing soon
• How to Read Hazardous-Location Equipment MarkingsLocating class, group, temperature code and protection techniqueComing soon
• How to Identify Lamp Base TypesMedium, candelabra, bi-pin and other basesComing soon
• How to Identify LED Driver TypesConstant current vs constant voltage, dimming protocols and class ratingsComing soon
• How to Read Lug and Terminal RatingsCU/AL marking, wire range and temperature markings on lugsComing soon
• How to Identify Ground Rod MaterialCopper-bonded, galvanized and stainless rods and their markingsComing soon
• How to Measure Cable OD for Glands and ConnectorsMeasuring jacket and armor OD to select a cord grip or MC connectorComing soon
• How to Identify Counterfeit Electrical ProductsWarning signs on breakers, cords, connectors and listing marksComing soon
• How to Identify Legacy Wiring (Knob-and-Tube, Cloth, Aluminum Branch)Recognizing older wiring methods customers bring inComing soon

Insulation, Jackets & Ratings

Insulation and jacket materials, temperature, voltage, location and fire ratings, plus electrical PPE ratings.

• Insulation Materials (PVC, Nylon, XLPE, EPR, Silicone)Common insulation compounds and their propertiesComing soon
• Conductor Temperature RatingsWhat 60, 75, 90 and higher temperature ratings mean and where they applyComing soon
• Wet, Damp and Dry Location RatingsLocation definitions and how wire and devices are rated for themComing soon
• Voltage Ratings of Wire and Cable300 V, 600 V, 1000 V and MV ratings and why they matterComing soon
• Sunlight-Resistant and UV-Rated JacketsWhat "sunlight resistant" marking means and where it is requiredComing soon
• Direct-Burial RatingsWhich cables and conduits are marked for direct burialComing soon
• Plenum, Riser and General-Purpose Fire RatingsCMP/CMR/CM and similar hierarchies and permitted substitutionsComing soon
• Low-Smoke Zero-Halogen (LSZH) CableWhat LSZH means and where it is specifiedComing soon
• Oil-Resistant Ratings (Oil Res I / II)Oil-resistance markings on MTW, tray cable and cordsComing soon
• Circuit Integrity and Fire-Rated CableCables and systems that maintain operation during a fireComing soon
• Electrical Tape Types and RatingsVinyl, rubber, mastic and varnished cambric tapesComing soon
• Heat-Shrink Tubing (Shrink Ratios and Wall Types)Thin, medium and heavy wall, adhesive-lined and ratingsComing soon
• Wire Markers and Labeling MaterialsLabel materials, durability and code-required markingComing soon
• Conduit Coatings (Galvanized, PVC-Coated, Stainless)Corrosion-resistant conduit optionsComing soon
• Corrosive Environment Selection GuideChoosing raceway and enclosures for chemical, coastal and washdown areasComing soon
• Rubber Insulating Gloves and Sleeves (Classes 00-4)Glove classes, testing intervals and the federal ruleComing soon
• Arc-Rated Clothing and PPE CategoriesArc ratings, PPE categories and label readingComing soon
• Insulated Hand Tools (1000 V)What 1000 V rated tools are and how they are markedComing soon

Engineering & Failure Analysis

Why electrical products fail, how problems are diagnosed and the engineering concepts behind common field issues.

• Voltage Drop: Why It Matters and How to Estimate ItCauses of voltage drop and the code informational notesComing soon
• Loose Connections and Thermal FailureHow loose terminations overheat and how to prevent itComing soon
• Torque for Electrical TerminationsWhy marked torque values must be followed and how to verifyComing soon
• Aluminum Wiring Termination FailuresOxidation, creep and listed remediesComing soon
• Insulation Resistance (Megger) Testing BasicsWhat an IR test shows and safe practiceComing soon
• Ground Resistance Testing BasicsFall-of-potential and clamp-on methodsComing soon
• GFCI and AFCI Nuisance TrippingCommon causes and diagnostic stepsComing soon
• Harmonics and Neutral OverheatingNonlinear loads, triplen harmonics and shared neutralsComing soon
• Motor Failure ModesWinding, bearing, voltage imbalance and single-phasing failuresComing soon
• Conduit and Box Corrosion FailuresGalvanic, chemical and moisture-related raceway failuresComing soon
• Cable Pulling Damage and Jacket FailurePulling tension, sidewall pressure and lubricant compatibilityComing soon
• Arc Flash: How Incident Energy Is DeterminedIncident energy analysis vs PPE category methodComing soon
• Shock Protection Boundaries ExplainedLimited and restricted approach boundaries and who may cross themComing soon
• Surge Damage and SPD FailureRecognizing surge damage and SPD end of lifeComing soon
• Thermal Imaging for Electrical MaintenanceWhat infrared surveys find and their limitsComing soon
• Transformer Overheating and LoadingOverload, harmonics and ventilation issuesComing soon
• Selective Coordination BasicsWhat coordination means and where the code requires itComing soon
• Water Intrusion in Conduit and BoxesCondensation, raceway seals and drainageComing soon

Specification & Engineering Control

Writing, reading and controlling electrical specifications, listings and substitutions.

• Writing a Clear Wire and Cable Spec LineElements of a complete wire and cable descriptionComing soon
• CSI MasterFormat Division 26 OverviewHow electrical spec sections are organizedComing soon
• Listed vs Labeled vs Recognized ComponentsWhat each term means and why it mattersComing soon
• Electrical Submittals and Cut SheetsPreparing complete submittalsComing soon
• Substitutions and "Or Equal" in Electrical SpecsHandling substitution requestsComing soon
• Series-Rated Breaker CombinationsWhat series ratings are and the labeling rulesComing soon
• Short-Circuit Current Rating (SCCR) ExplainedSCCR vs interrupting rating and panel markingComing soon
• Industrial Control Panel Specs (UL 508A)What UL 508A listing coversComing soon
• Buy America / BABA for Electrical ProductsDomestic content rules on funded projectsComing soon
• Energy Code Requirements for Lighting and ControlsLighting power and control requirementsComing soon
• NEC Code Cycle AdoptionHow code editions are adopted locally and why it matters for stockComing soon
• Hazardous Location Specification ChecklistInformation needed before quoting classified-area productsComing soon
• Labeling Requirements for Electrical EquipmentField-marking and warning label rulesComing soon
• Prefabrication and Kitting SpecsSpecifying pre-made whips, assemblies and kitsComing soon

Procurement & Cost Reduction

Buying, pricing and cost-reduction topics for electrical distribution.

• Copper Price Volatility and Metals EscalatorsHow copper pricing moves wire quotes and escalator clausesComing soon
• Cut-to-Length vs Full-Reel PricingPricing cut charges, minimums and remnant costComing soon
• Reel Deposits, Returns and Reel SizesManaging reel deposits and returnable reelsComing soon
• Lot Pricing vs Item Pricing for ProjectsQuoting wire and conduit packagesComing soon
• Standardizing Breaker and Device BrandsReducing SKUs without hurting serviceComing soon
• Total Cost of Ownership: Labor-Saving ProductsPre-wired, push-in and modular products vs laborComing soon
• Quoting Lighting PackagesFixture schedules, substitutions and controlsComing soon
• Lead Times on Switchgear and TransformersPlanning and expediting long-lead gearComing soon
• Avoiding Gray-Market and Unauthorized BreakersSourcing risks and authorized channelsComing soon
• Utility Rebates and IncentivesUsing lighting and motor rebates in quotesComing soon

Quality, Compliance & Traceability

Listings, product compliance, recalls and traceability for electrical products.

• Verifying UL, CSA and ETL Listing MarksHow to confirm a listing is genuineComing soon
• The OSHA NRTL Program ExplainedWhat a Nationally Recognized Testing Laboratory isComing soon
• Counterfeit Electrical Product ResponseWhat to do when a counterfeit is suspectedComing soon
• Country of Origin MarkingOrigin marking rules for imported productsComing soon
• RoHS and REACH for Electrical ProductsRestricted substances rules for export customersComing soon
• California Proposition 65 WarningsWarning requirements on wire, cords and devicesComing soon
• Reel and Lot Traceability for WireTracking reel numbers through cuts and salesComing soon
• Returns and Damaged-Goods InspectionInspecting returned devices and wire before restockComing soon
• Recall Monitoring (CPSC and Manufacturers)Tracking and acting on recall noticesComing soon
• Certificates of Compliance and Test ReportsWhat paperwork customers can ask forComing soon

Inventory, VMI & Automation

Stocking, vendor-managed inventory and automation for electrical products.

• Wire Room Management and Cut TrackingRunning a wire cutting operation accuratelyComing soon
• Reel Inventory and Remnant ControlTracking footage on partial reelsComing soon
• Jobsite Trailer Min/Max ProgramsStocking contractor trailers and gang boxesComing soon
• Kitting and Job StagingBuilding job kits and staged releasesComing soon
• Breaker and Fuse Stocking by Panel BrandChoosing which breaker families to stockComing soon
• Barcode and Labeling for Electrical SKUsUPCs, bin labels and scanningComing soon
• VMI for Industrial MRO ElectricalManaging customer storeroomsComing soon
• Dead Stock and Code-Cycle ObsolescenceProducts made obsolete by code changesComing soon
• Vending for Consumables (Tape, Connectors, Ties)Using vending machines for small consumablesComing soon
• Cycle Counting High-Value ItemsCounting copper, breakers and gearComing soon