Short answer: Grounding establishes an intentional connection to earth, while the equipment grounding and bonding system also serves critical fault-current-path functions. Bonding is the intentional connection of conductive parts to establish electrical continuity and conductivity. A properly installed equipment grounding and bonding path helps return fault current to its source so the overcurrent device can operate. The common mistakes: trusting the earth to clear faults, bonding neutral and ground downstream, and sizing or upsizing grounding conductors wrong.
Grounding and bonding appear in both parts of the Texas Journeyman exam. The PSI outline lists it under services, feeders and branch circuits in NEC Knowledge, and under services and branch-circuit conductors in Calculations. The Texas Journeyman Practice Pack has 1,000 practice questions on the 2026 NEC and 10 timed two-part mocks. US$39 once.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain Article 250 in our own words and quote only the values our examples need. Check every rule in your own 2026 NEC, and follow your supervising electrician on real installations. Texas uses the 2026 NEC for installations and exams from September 1, 2026 (TDLR rule adoption notice).
Grounding vs bonding: the parts
| Part | What it does |
|---|---|
| Grounding electrode | The connection to earth, such as a ground rod or a concrete-encased electrode |
| Grounding electrode conductor (GEC) | Connects the system at the service to the grounding electrode |
| Equipment grounding conductor (EGC) | A conductor or recognized wiring-method path that helps establish an effective ground-fault current path back toward the source. Under fault conditions, the complete path must permit sufficient fault current for the protective device to operate as required. |
| Main bonding jumper | The connection at the service equipment between the neutral (grounded conductor) and the equipment grounding system in a typical service-fed system |
| Bonding jumper | Any conductor that joins metal parts so they are electrically continuous |
The 2026 NEC added or revised Article 100 definitions to tell the different bonding jumpers apart, such as equipment, main, supply-side and system bonding jumpers (City of Denison 2026 NEC summary). Learn the names; exam questions use them precisely.
Mistake 1: trusting the earth to clear a fault
The NEC says the earth by itself is not an effective ground-fault current path (Section 250.4; confirm the subsection in your 2026 book). The numbers show why. These are simplified classroom calculations, not instructions for testing or intentionally creating electrical faults. Never energize or fault equipment to reproduce them.
For a simplified classroom model, assume a 120-volt fault has a hypothetical total return-path impedance of 25 ohms. This is not a measurement or prediction of an actual ground-rod fault-current path, which depends on additional soil, electrode, and source conditions.
- Fault current: 120 ÷ 25 = 4.8 amperes.
- In this hypothetical model, 4.8 amperes is below the 20-ampere breaker’s rated current, so this fault current would not be expected to cause an overcurrent trip. The exposed conductive part could remain energized and present a serious shock hazard. Actual protective-device behavior depends on the device and the complete circuit conditions.
For comparison, assume a hypothetical effective fault-current return path with a total impedance of 0.5 ohm. This is a classroom model, not a measured installation or a prediction of breaker clearing time:
- Fault current: 120 ÷ 0.5 = 240 amperes.
- That is 12 times the breaker’s rating (240 ÷ 20 = 12). The actual clearing time depends on the breaker’s time-current characteristics and the whole fault-current path.
A ground rod has important jobs, but earth alone is not an effective fault path. The equipment grounding and bonding connections must provide the path that lets the overcurrent device operate.
Mistake 2: bonding neutral and ground in a subpanel
In a typical service-fed system, the neutral (grounded conductor) is bonded to the equipment grounding system at the service equipment, through the main bonding jumper. Separately derived systems, such as a transformer, have their own bonding requirements, so check the 2026 NEC provisions before deciding where a connection belongs. In the typical arrangement described here, downstream panels in the same building keep the neutral bar isolated from the enclosure and the grounding bar.
If you bond them again in a subpanel, normal neutral current splits onto the grounding conductors, raceways and metal enclosures. Metal that should carry current only during a fault now carries it all the time. Do not install or remove a bonding screw or strap on the basis of this article. Panel work must be done by qualified personnel under the required supervision, after electrical safety procedures and a check of the code and the manufacturer’s instructions.
Mistake 3: sizing the EGC from the wire instead of the breaker
The minimum size of a wire-type equipment grounding conductor starts with the applicable overcurrent protective device rating and Table 250.122. Confirm the 2026 subsection requirements, exceptions, and any conductor-upsizing provisions before selecting the final size.
| Overcurrent device not over | Copper EGC (AWG) |
|---|---|
| 15 A | 14 |
| 20 A | 12 |
| 60 A | 10 |
| 100 A | 8 |
| 200 A | 6 |
Only the rows used on this page. Read the full table in your code book.
Example: a 40-ampere breaker. 40 is more than 20 and not more than 60, so the copper EGC is at least 10 AWG.
Mistake 4: forgetting to upsize the EGC
When ungrounded conductors are increased in size under conditions covered by the applicable NEC equipment-grounding-conductor upsizing rule, the wire-type EGC may also need to be increased proportionally by circular mil area. Apply the applicable 2026 NEC conditions and exceptions when selecting the final EGC size. Conductor areas come from Chapter 9, Table 8.
Example: a 20-ampere circuit is run in 10 AWG instead of 12 AWG copper because of a long run.
- Areas: 12 AWG is 6,530 circular mils; 10 AWG is 10,380 circular mils.
- Ratio: 10,380 ÷ 6,530 = 1.5896.
- Required EGC area: 6,530 × (10,380 ÷ 6,530) = 10,380 circular mils. Keep the full ratio during the calculation and select the conductor size required by the applicable NEC rule.
- Result: a 10 AWG copper EGC.
Check: the ratio is exact here because the EGC and the circuit conductors started at the same size, so the EGC simply follows them up to 10 AWG.
Mistake 5: mixing up the GEC and the EGC
They have different jobs and different sizing tables. For applicable service installations, GEC sizing begins with Table 250.66 and the relevant service-conductor size; electrode-specific sizing rules and exceptions must then be checked. The EGC is sized from the overcurrent device using Table 250.122.
Example: a service with 2/0 copper service-entrance conductors.
- Table 250.66, for 2/0 or 3/0 copper: a 4 AWG copper GEC.
- A separate sizing exception may apply to a grounding electrode conductor connected only to qualifying rod, pipe, or plate electrodes; check the applicable 2026 NEC requirements for that electrode arrangement.
According to the City of Denison summary above, the 2026 NEC also allows a GEC to be spliced in an accessible location with listed grounding and bonding fittings; confirm the conditions in your book.
Disclosure: If you buy through the Amazon link below, Tsai Electro may earn a commission at no extra cost to you. As an Amazon Associate I earn from qualifying purchases.
The code book for grounding and bonding
NFPA 70, National Electrical Code (NEC) 2026, softbound. The sections in this article, including 250.66 and 250.122, are in Article 250 of the 2026 edition. Read each one in your own copy before you rely on it.
Check yourself
Our own practice questions. Answers below each.
- A 100-ampere breaker protects a feeder. What is the minimum copper EGC? Answer: 8 AWG, from Table 250.122.
- A 30-ampere circuit is run in 8 AWG instead of 10 AWG copper. What size copper EGC? Answer: Ratio 16,510 ÷ 10,380 = 1.5906. The 10 AWG EGC becomes 10,380 × 1.5906 = 16,510 circular mils (rounded), which is 8 AWG.
- A house has a main panel at the service and a subpanel in the same building. Where are neutral and ground bonded? Answer: In the typical arrangement described here, at the service through the main bonding jumper. Other system configurations, such as separately derived systems, have their own bonding rules.
FAQ
What is the difference between grounding and bonding?
Grounding connects the electrical system or equipment to the earth. Bonding establishes electrical continuity between conductive parts. When properly integrated with the equipment grounding and bonding system, it helps establish an effective ground-fault current path that allows the protective device to operate as required.
Why are neutral and ground separated in a subpanel?
So that normal neutral current returns only on the neutral. In the typical service-fed arrangement, the neutral stays isolated from the equipment grounding system downstream of the service bonding point. Other system configurations have their own rules. Bonding them again downstream puts neutral current on grounding conductors and metal parts.
How do you size an equipment grounding conductor?
From the rating of the overcurrent device protecting the circuit, using Table 250.122. If the ungrounded conductors are upsized, the wire-type EGC is generally increased in proportion by circular mil area, subject to the code’s conditions.
Does a ground rod trip the breaker during a fault?
Not by itself. The earth is not an effective fault path. In a simplified example with a hypothetical 25-ohm return path on a 120-volt circuit, fault current is only about 4.8 amperes, far below the rating of a 20-ampere breaker. The equipment grounding and bonding path provides the route that lets the device operate.
Sources checked October 2026
- TDLR rule adoption notice, 2026 NEC: https://www.tdlr.texas.gov/news/rulemaking/2026/09/01/commission-adopts-rules-12/
- PSI Candidate Information Bulletin for TDLR (updated 9/15/2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- City of Denison, 2026 NEC significant changes: https://denisontx.gov/DocumentCenter/View/4131/2026-National-Electrical-Code-Significant-Changes
- NFPA 70 (NEC), 2026 edition, Article 250 and Chapter 9 Table 8, read in your own copy: https://www.nfpa.org/codes-and-standards/nfpa-70-standard-development/70
