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TL;DR

Grounding and Bonding: Grounding connects systems to earth for voltage stabilization. Bonding connects metallic parts for electrical continuity.

By Valenke Exam Prep Team·Last updated 2026-06-02

Grounding and Bonding

JOURNEYMAN ELECTRICIANMASTER ELECTRICIAN

Definition

Grounding connects systems to earth for voltage stabilization. Bonding connects metallic parts for electrical continuity.

Calculation Methods

Calculations for grounding and bonding:

FormulaEquationExample
Voltage dropVD = (2 x K x I x D) / CM20A, 150ft, 12AWG (6530CM): VD = (2 x 12.9 x 20 x 150)/6530 = 11.87V (9.9%)
Power (3-phase)P = 1.732 x E x I x PF480V x 20A x 0.85 x 1.732 = 14,117W

Differential Diagnosis

When studying grounding and bonding, carefully distinguish it from related but distinct concepts: nec code, overcurrent protection, ohms law. Exam questions often test your ability to select the most specific and appropriate answer when multiple options seem partially correct. Look for the option that most completely addresses the scenario presented.

Equipment & Tools

Tools and equipment for grounding and bonding include multimeters (for voltage, current, and resistance measurement), clamp meters (for non-contact current measurement), megohmmeter (for insulation resistance testing), and conduit benders (for EMT and rigid conduit). All test equipment must be rated for the voltage being measured. A Category III meter minimum for distribution-level work, Category IV for service entrance.

Overview

Grounding connects systems to earth for voltage stabilization. Bonding connects metallic parts for electrical continuity. Among the most heavily tested JE and ME topics. Must distinguish GECs, EGCs, and bonding jumpers.

Relevant formula: Conduit fill is 1 wire=53%, 2 wires=31%, 3+ wires=40% of conduit area. Variables: Wire area from Chapter 9 Table 5, conduit area from Table 4.

Why It Matters

Among the most heavily tested JE and ME topics. Must distinguish GECs, EGCs, and bonding jumpers.

Related Terms

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Frequently Asked Questions

What NEC articles cover grounding and bonding?
For grounding and bonding: Article 430 (Motors): 430.6: use FLC from Table 430.248/250 not nameplate for conductor/OCP sizing. Article 334 (Nonmetallic-Sheathed Cable (NM/Romex)): Not permitted in commercial buildings over 3 stories.
What are common code violations related to grounding and bonding?
For grounding and bonding: Missing GFCI: Bathroom, kitchen, garage, outdoor, and crawl space receptacles require GFCI per 210.8. Backstab connections: Push-in connections on receptacles fail more often than screw terminals, poor practice though not a code violation. Improper grounding: Bootleg ground (jumping neutral to ground at receptacle) or missing EGC.
What formulas are needed to calculate grounding and bonding?
For grounding and bonding: Box fill: Sum of: conductors x volume + clamp allowance + device allowance + EGC allowance. Variables: Per Table 314.16(B): 14AWG=2.0 cu in, 12AWG=2.25 cu in, 10AWG=2.5 cu in. Example: 4 x 12AWG + 1 device + 1 EGC = (4+2+1) x 2.25 = 15.75 cu in minimum.