Electrical how-to guides, written by the trade
Practical, NEC-referenced field guides from a licensed commercial contractor — the same fundamentals our crews use every day. Pair them with our free calculators.
Power & Distribution
Power & Distribution
How to Wire a Three-Phase Transformer →
Wire a 480V delta to 208Y/120V dry-type step-down: conductors, OCPD per 450.3(B), 250.30 grounding, taps, torque, and energization.
Power & DistributionHow to Size a Bonding Jumper →
Which table applies to which jumper, the 12.5% rule over 1100 kcmil, parallel runs, and worked examples you can check your math against.
Power & DistributionHow to Size a Grounding Electrode Conductor →
Size the GEC from Table 250.66, apply the rod and Ufer caps, and bond the whole electrode system right the first time.
Power & DistributionHow to Install a Commercial Subpanel →
Feeder sizing, isolated neutral, working clearances, and AIC — the right way to add a panelboard downstream of the service.
Wiring Methods
Wiring Methods
How to Wire a Commercial Outlet →
Box selection, MC makeup, pigtails vs feed-through, 210.8(B) GFCI rules, and torque specs for a 20A commercial receptacle.
Wiring MethodsHow to Bend EMT Conduit →
Take-up, offset multipliers, shrink, kicks, and saddles — plus the 360° rule — so your EMT runs come out clean the first time.
Wiring MethodsHow to Pull Wire Through Conduit →
Verify fill, set up the pull right, and land conductors without damage — from pull string to bushings.
Wiring MethodsHow to Identify Commercial Wire Colors →
Read phase, neutral, and ground colors on 120/208V and 277/480V systems — and know which colors the NEC actually mandates.
Wiring MethodsHow to Terminate MC Cable →
Cut the armor clean, use listed fittings, secure within 12 inches — MC terminations done right, per NEC Article 330.
Motors & Controls
Motors & Controls
How to Wire a Three-Phase Motor Starter →
Power wiring, 3-wire control with seal-in, overload settings per 430.32, and branch-circuit sizing per 430.22 — start to bump test.
Motors & ControlsHow to Wire a 480V Disconnect →
Size, mount, and terminate a 480V safety switch for RTUs and motors — fusible vs non-fusible, NEC 430.110 and 440.14, phase rotation.
HVAC & Mechanical
HVAC & Mechanical
How to Wire a Rooftop Unit (RTU) →
Read MCA/MOP off the nameplate, size the circuit, mount the disconnect per 440.14, land the whip, and handle the Arizona rooftop ampacity adder.
HVAC & MechanicalHow to Install a VFD (Variable Frequency Drive) →
Size input conductors at 125% of rated input current per 430.122, protect per 430.130, run shielded output cable, and bond it like the noise source it is.
HVAC & MechanicalHow to Run Thermostat & BAS Control Wiring →
Class 2 rules under Article 725, CL2P in plenums, keeping control apart from power, R-C-G-Y-W conventions, and clean BAS network topology.
Underground & Site Work
Underground & Site Work
How to Install Underground Conduit →
Table 300.5(A) cover depths, the 352.44 expansion-fitting math Arizona forces on you, warning ribbon, long-radius sweeps, and clean backfill.
Underground & Site WorkHow to Build a Duct Bank →
Lay out the window, set conduits on spacers, pour without floating the bank, understand mutual-heating derates, and proof every duct before turnover.
Underground & Site WorkHow to Set a Light Pole Base →
Template the anchor bolts, land the conduit inside the bolt circle, ground per 410.30(B), and set poles plumb — with the 480V height rule in mind.
Testing & Workmanship
Testing & Workmanship
How to Megger Test a Motor or Feeder →
Insulation resistance testing done right: voltages, minimum megohms, temperature correction, and clean baseline records.
Testing & WorkmanshipHow to Torque Electrical Terminations →
NEC 110.14(D) makes torqued terminations mandatory. Finding the values, using the right tools, and skipping the retorque myths.
Testing & WorkmanshipHow to Test Ground Resistance →
The 25-ohm rule, running a proper three-point fall-of-potential test with the 62% method, when a clamp-on tester is valid, and what desert soil does to your numbers.
Testing & WorkmanshipHow to Verify Phase Rotation & Voltage →
Meter every new service and motor circuit: rotation before load, voltage line-to-line and line-to-ground, the high-leg trap, and a disciplined bump test.
Testing & WorkmanshipHow to Read an Arc Flash Label →
Decode incident energy, working distance, arc flash boundary, and PPE requirements — and know when a label is stale enough to distrust.
Lighting & Life Safety
Lighting & Life Safety
How to Wire a Lighting Contactor →
Mechanically vs electrically held contactors, photocell/time clock logic, HOA switches, and sizing for parking lot and site lighting.
Lighting & Life SafetyHow to Wire an Exit Sign and Emergency Light →
The unswitched-hot rule, the three-wire hookup, and the testing duties for battery-backup exit signs and emergency lights.
Service & Energy
Service & Energy
How to Wire a Generator Transfer Switch →
Classify the system first — 700, 701, or 702 — then size per the article, and answer the neutral-switching question before you buy the switch.
Service & EnergyHow to Install a Commercial EV Charger →
Size at 125% per 625.41, use the 625.42 EMS allowance to fit more chargers on the service, and get the site details — mounting, protection, signage — right.
Service & EnergyHow to Terminate Aluminum Feeders →
Modern AA-8000 aluminum terminates reliably — with dual-rated lugs, a brushed and inhibited conductor, the right torque, and no copper-era shortcuts.
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