MHE Field Notes
Plain-language writing on the code, the exams and the reasoning behind the rules — written for people already on the tools, not for a classroom.
MHE Field Notes
The Terminal Rating Decides, Not the Wire Insulation
Why sizing a conductor from the 90-degree column and stopping there gets you written up, where the twenty-amp rule for #12 actually comes from, and how the two rules f...
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Same Wire, Different Attic, Different Ampacity
Ambient temperature correction and conductor-count adjustment are two separate multipliers that stack, and they are applied in an order most people reconstruct from me...
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A Breaker Protects the Wire, Not the Person
Overcurrent devices watch how much current flows. Ground-fault devices watch where it goes. Confusing the two is the most common and most consequential misunderstandin...
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The Six-Foot Rule and the Reasoning Behind It
Receptacle spacing in dwellings is not an outlet every six feet, and wall space is a defined term that is broader than the plaster. The rule exists so nobody reaches f...
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Two Small-Appliance Circuits and What They May Serve
The kitchen rule is about two appliances running at once, not about total load. Understanding it that way explains what the circuits may cover and the three things ins...
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NM, UF, THHN, MC and SE in Their Proper Places
Each of these was designed and listed for a particular set of conditions. Substituting one for another produces an installation that works perfectly right up until it ...
Read more →Code reasoning, in plain language.
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