CT Electrician cheat sheet

Ohm's law: E = I × R, with rearranged forms I = E/R and R = E/I for DC and resistive AC circuits.

Power relationships: P = E × I = I² × R = E²/R; 1 horsepower = 746 watts; 1 kWh = 1,000 watts for one hour.

Balanced three-phase power: P = √3 × E(line) × I(line) × power factor.

Single-phase voltage drop: VD = (2 × K × I × L) ÷ circular mils, where K = 12.9 for copper and 21.2 for aluminum.

Conductors in parallel must be 1/0 AWG or larger and identical in material, size, length, insulation, and termination method.

In a 3-wire 120/240 V single-phase system the neutral carries only the unbalanced current; a 240 V load connects line-to-line.

Ampacity is first corrected for ambient temperature, then derated when more than three current-carrying conductors share a raceway.

Skin effect raises effective AC resistance above the DC value listed in Chapter 9, Table 8, especially in large conductors.

GFCI protection is required for 125 V, 15- and 20-A receptacles in bathrooms, garages, outdoors, crawl spaces, unfinished basements, and kitchen countertop areas.

AFCI protection is required for branch circuits supplying outlets in dwelling unit kitchens, bedrooms, living rooms, laundry areas, and similar rooms.

Dwelling receptacle spacing: no point along a wall line may be more than 6 ft from a receptacle, and wall spaces 2 ft or wider require one.

The next-size-up rule allows an overcurrent device rated 800 A or less to exceed conductor ampacity where ampacity falls between standard ratings.

Working space at electrical equipment: 3 ft deep, 30 in wide, 6½ ft high, with depth increased for exposed live parts.

Equipment grounding conductors are sized from Table 250.122 using the rating of the circuit overcurrent protective device.

Up to six service disconnects are permitted in a single service, grouped in one location and marked as service equipment.

The grounding electrode conductor is sized from Table 250.66 based on the largest service-entrance conductor.

Conduit fill limits: 53% for one conductor, 31% for two conductors, 40% for three or more, based on Chapter 9, Table 1.

Box fill: each 14 AWG conductor counts 2.0 cu in, 12 AWG counts 2.25, 10 AWG counts 2.5; each yoke counts as two of the largest conductor.

Type NM cable must be secured within 12 in of a box and supported at intervals not exceeding 4½ ft.

Type NM cable is not permitted in wet locations, in masonry or concrete, or where subject to physical damage.

Direct-buried residential branch circuits at 120/240 V need 24 in of cover, reduced to 18 in with GFCI protection and a 20 A maximum.

EMT must be supported at intervals not exceeding 10 ft and within 3 ft of each box or fitting.

Rigid metal conduit must be supported within 3 ft of termination and at intervals not exceeding 10 ft.

The grounded conductor is identified by white or gray; the equipment grounding conductor by green, green with yellow stripes, or bare.

Motor branch-circuit conductors are sized at 125% of the full-load current taken from the code tables, not the nameplate current.

Motor overload protection is sized to nameplate current; short-circuit and ground-fault protection is selected from Table 430.52.

A motor disconnecting means must be within sight of the motor and controller, or capable of being locked in the open position.

Flexible cords may not be used as a substitute for the fixed wiring of a structure or run through walls, ceilings, or floors.

Switches and circuit breakers must be installed so the highest position does not exceed 6 ft 7 in above the floor.

Receptacles installed in dwelling units must be listed tamper-resistant.

Transformer overcurrent protection must comply with Table 450.3(B), which sets the permitted primary-only and primary-and-secondary arrangements.

Luminaires in clothes closets must maintain the storage-space clearances specified by code.

Class I locations contain flammable gases or vapors; Class II locations contain combustible dust; Class III locations contain easily ignitable fibers or flyings.

Division 1 covers conditions expected under normal operation; Division 2 covers conditions expected only under abnormal operation.

Zone systems classify gases as Zone 0, 1, or 2 and dusts as Zone 20, 21, or 22.

Patient care areas of health care facilities require redundant grounding: a metallic raceway or armored cable plus an insulated copper conductor.

Critical care areas use isolated power systems with line isolation monitors that alarm at 5 mA.

In commercial garages the space within 18 in of the floor is classified as a Class I, Division 2 location.

Assembly occupancies require emergency lighting and exit illumination with an approved power source.

Swimming pools require an equipotential bonding grid for the shell, metal fittings, ladders, and adjacent metal, using copper not smaller than 8 AWG.

Receptacles are prohibited within 6 ft of a pool's inside wall, and receptacles within 20 ft require GFCI protection.

Photovoltaic systems require a rapid shutdown function that limits conductor voltage within the array boundary.

A PV system disconnecting means must be installed at a readily accessible location and marked with a plaque.

Fire pump conductors must have continuity of power and may not be protected by a ground-fault device that opens the circuit.

Electric vehicle supply equipment rated over 60 A or over 150 V to ground requires a listed disconnecting means.

Elevators, escalators, and moving walks are covered by Article 620, including traveling cables and machine room bonding.

Emergency systems (Article 700) serve life-safety loads; legally required standby is Article 701; optional standby is Article 702.

Emergency system wiring must be kept independent of normal wiring and protected against fire damage.

A Class 2 circuit supplied by a listed Class 2 power source is limited to 100 VA, permitting smaller conductors and reduced installation rules.

Fire alarm circuits are covered by Article 760 and must use listed fire-protection cable or raceway.

Class 1 remote-control and signaling circuits are limited only by their overcurrent protection, unlike Class 2 and 3 circuits.

Interconnected electric power production sources are governed by Article 705 and require a dedicated disconnecting means.

Sensitive electronic equipment branch circuits are addressed by Article 647 for separately derived systems.

Article 800 covers communications circuits, Article 820 covers coaxial cable distribution, and Article 830 covers network-powered broadband.

A listed primary protector is required where communications conductors enter a building and are exposed to lightning.

Communications cable must be bonded to the building grounding electrode system with copper not smaller than 14 AWG.

Communications cables must be separated from power conductors by at least 2 in where they run in close parallel paths.

Abandoned communications cable that cannot be identified for future use must be removed.

Communications cables may not occupy the same raceway or enclosure as light, power, Class 1, or non-power-limited fire alarm conductors.

A lump-sum contract fixes one price for the entire scope, shifting quantity and price risk to the contractor.

Time-and-materials contracts bill actual labor hours at a stated rate plus material cost and markup.

Retainage is a portion of each progress payment, commonly 5% to 10%, held until final acceptance.

A change order must be written and signed before the work proceeds to protect the right to payment.

Overhead covers indirect costs such as insurance, vehicles, rent, and licenses; profit is added after direct and indirect costs.

A mechanics lien is a claim against the property for unpaid labor and materials, with deadlines set by statute.

Employers in Connecticut must carry workers' compensation insurance and register for unemployment tax.

The licensed contractor obtains permits before work starts; permit fees are set by the local authority.

A drawing scale of 1/8 in = 1 ft means one inch on the plan equals 8 feet of actual dimension.

Conductor takeoff typically adds 5% to 10% waste; boxes and devices typically add 2% to 5%.

Bid price = direct material + direct labor + subcontractors + overhead + profit, plus contingency for uncertain scope.

A riser diagram shows the service, feeders, panelboards, disconnects, and grounding without physical dimensions.

A panel schedule lists circuit numbers, breaker ratings, connected loads, and phase balance.

Floor plan symbols identify lighting outlets, receptacles, switches, and special equipment locations.

Labor units expressed in hours per item are multiplied by the loaded hourly rate to produce labor cost.

Quantities are counted by item and extended to price using current supplier quotations, not catalog list prices.

Lockout/tagout: open the disconnect, apply a personal lock and tag, then verify the circuit is de-energized with a tester before work.

Rubber insulating glove classes: Class 00 rated 500 V AC, Class 0 rated 1,000 V AC, Class 2 rated 17,000 V AC.

The limited approach boundary for exposed live parts at 750 V or less is 10 ft; only qualified persons may cross it.

On construction sites all 125 V, 15- and 20-A receptacle outlets must have GFCI protection or an assured equipment grounding conductor program.

Ladder setup follows the 4-to-1 rule, with the ladder extending 3 ft above the landing.

Test the tester on a known live source before and after verifying a circuit is de-energized.

Confined space entry requires atmospheric testing, an attendant, and permit documentation before entry.

Head protection, eye protection, and arc-rated clothing are selected from the incident energy and hazard risk category of the task.

Connecticut adopts NFPA 70 with Connecticut amendments; the amended State Building Code governs permitting and inspection.

Electrical licenses are issued and renewed by the Department of Consumer Protection under Chapter 393 of the Connecticut General Statutes.

License classes include the E-1 electrical contractor and E-2 journeyman electrician, plus the limited L-5 and L-6 licenses.

Apprentices must be registered with the state and work under the supervision of a licensed electrician.

Local building officials issue electrical permits and the electrical inspector approves the work before it is concealed.

Only a licensed electrical contractor may offer or contract to perform electrical work for the public.

License renewal requires payment of the renewal fee and completion of the continuing education required for that license class.

Ohm's law: E = I × R, with rearranged forms I = E/R and R = E/I for DC and resistive AC circuits.

Power relationships: P = E × I = I² × R = E²/R; 1 horsepower = 746 watts; 1 kWh = 1,000 watts for one hour.

Balanced three-phase power: P = √3 × E(line) × I(line) × power factor.

Single-phase voltage drop: VD = (2 × K × I × L) ÷ circular mils, where K = 12.9 for copper and 21.2 for aluminum.

Conductors in parallel must be 1/0 AWG or larger and identical in material, size, length, insulation, and termination method.

In a 3-wire 120/240 V single-phase system the neutral carries only the unbalanced current; a 240 V load connects line-to-line.

Ampacity is first corrected for ambient temperature, then derated when more than three current-carrying conductors share a raceway.

Skin effect raises effective AC resistance above the DC value listed in Chapter 9, Table 8, especially in large conductors.