On the job
The diagrams teach you how a circuit works; these pages teach the things you get handed on site and are expected to already know. The meter in your pouch and what its rating actually promises. The lock you put on a disconnect and why nobody else's lock will do. The panel schedule that is half wrong. The devices in the box, and how to tell a 3-way from a single-pole without reading the packet. The motor nameplate, the little transformer feeding the control circuit, the data cable somebody wants run beside the power, and the bender that will eat your first ten sticks of EMT.
None of this is install instructions. It is the idea behind each thing and the habit that goes with it, so that when a journeyman says "go lock that out" or "what's the FLA on that motor" you know what is being asked and where the real answer lives.
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Meter safety and CAT ratings
What the rating on your meter means, why the leads matter as much as the meter, and the live-dead-live habit.
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Using a multimeter
Voltage, continuity, resistance and current — how to take each reading so it tells the truth, and the two readings that lie.
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Lockout / tagout, walked through
Every energy source isolated, your own lock on it, proven dead — step by step, and why a tag alone is not a lock.
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Reading a panel schedule
How breaker numbers run, why a two-pole lands on two legs, and how to find the circuit you are after.
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Common wiring devices
Switches, receptacles, GFCIs and the rest — what the screws tell you and how to know which device is in the box.
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Reading a motor nameplate
Horsepower, volts, full-load amps, service factor, frame, code letter — what each field is for.
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Transformer basics
Turns ratio, step-up and step-down, kVA, and the control transformer with its H and X terminals.
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Low-voltage and data basics
Twisted pairs, why they twist, separation from power, bend radius, and what a patch panel is for.
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Conduit bending basics
The bender, its marks, the three bends you learn first, and where the math lives when you need it.
How these pages are written
Each page explains the idea and the habit — what the thing is for, how to read it, what goes wrong, and what the person checking your work is looking for. What each page does not do is hand you a number that belongs somewhere else. Where a value is set by the code, the page says "that is in your book". Where it is set by the manufacturer, it says "read the nameplate" or "read the label". Where it is set by your employer's written procedure — lockout is the big one — it says so and stops. That is not caution for its own sake: a number quoted out of its book, without the conditions attached, is how the wrong one gets applied.
Read them in any order. If you are brand new, the meter page and the lockout page come first, because everything else assumes you can prove a circuit dead and keep it that way.
The bending page here explains the bender and the marks. When you are actually at it and need an offset or a saddle worked out, bentright.com does the numbers.
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