Short answer: These sections bond metal that is not part of a circuit, so a fault on it can open the breaker instead of leaving the metal energized. For piping and structural steel, the questions ask where the bonding connection goes and which table sizes the jumper. Service raceway questions ask which bonding methods are acceptable, and intersystem bonding questions ask about location and terminals. Other metal piping, including gas piping, that is likely to become energized is bonded and sized from Table 250.122 by the rating of the circuit that could energize it (NEC 250.104(B)). Exposed structural metal that is interconnected and likely to become energized is sized from Table 250.102(C)(1) (NEC 250.104(C)). At the service, raceways around concentric or eccentric knockouts get bonding jumpers (NEC 250.92(B)), and an intersystem bonding termination gives communications systems a place to bond (NEC 250.94(A)).
PSI lists grounding and bonding in the Services, Service Equipment and Separately Derived Systems subject area of the Texas Journeyman exam: 6 scored NEC Knowledge questions and 4 scored Calculations questions. PSI does not say how many cover these sections. The Texas Journeyman Practice Pack has 1,000 original questions and 10 timed mock exams in the real two-part format, with step-by-step solutions for every calculation. Try free practice questions without signing up. Get the full pack for US$39 with one payment.
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The two tables, and which one to open
| What you are bonding | Size it from | Based on |
|---|---|---|
| Other metal piping likely to become energized, such as gas piping | Table 250.122 | The rating of the circuit that could energize it |
| Exposed interconnected structural metal likely to become energized | Table 250.102(C)(1) | The service or supply conductors |
| Isolated metal water piping in one occupancy of a multiple-occupancy building | 250.102(D), which points to Table 250.122 | The overcurrent device rating, as 250.102(D) sets out |
Most wrong answers here come from opening the wrong table. Decide what is being bonded, then the table follows. For the basic difference between the equipment grounding conductor and the grounding electrode conductor, see the five common grounding and bonding mistakes; this page does not repeat it.
250.104: piping and steel
- Metal water piping, 250.104(A). The first part of 250.104(A) covers the usual building with one metal water system. Check its bonding points and sizing table in your 2026 NEC. In a multiple-occupancy building where each occupancy’s metal water piping is isolated from the others, each occupancy’s piping is permitted to be bonded to the equipment grounding terminal of the switchgear, switchboard or panelboard that supplies that occupancy, as an alternative connection point, with the jumper sized under 250.102(D) (NEC 250.104(A)(2)).
- Other metal piping, 250.104(B). Piping such as gas piping that is likely to become energized is bonded to the equipment grounding conductor of the circuit that could energize it, the service enclosure, the grounded conductor at the service, the grounding electrode conductor or an electrode. The bonding jumper is sized from Table 250.122 by that circuit’s rating (NEC 250.104(B)).
- Structural metal, 250.104(C). Exposed, interconnected structural metal that is likely to become energized is bonded to the service enclosure, the grounded conductor at the service, the disconnect of a building supplied by a feeder, a grounding electrode conductor of sufficient size or the electrodes. The jumper is sized from Table 250.102(C)(1) (NEC 250.104(C)).
250.92 and 250.94: at the service
- Knockouts at the service. Service raceways often land in boxes with concentric or eccentric knockouts. Leftover knockout rings can impair bonding continuity, so bonding jumpers are used around impaired connections, including those rings. Standard locknuts or bushings alone are not one of the permitted bonding methods there (NEC 250.92(B)).
- Over 250 volts to ground, 250.97. On circuits over 250 volts to ground, raceway continuity uses the 250.92(B) methods except the one in (B)(1). The exception for certain other connection methods does not apply where concentric or eccentric knockouts are encountered, unless the box is listed for it (NEC 250.97).
- Intersystem bonding termination. The device is outside the enclosures, accessible, has terminals for at least three intersystem bonding conductors, and sits at the service equipment or at the disconnect of a building supplied by a feeder (NEC 250.94(A)). It gives the phone, cable TV and other communications installers a place to bond without opening the panel.
Worked example 1: gas piping
A gas-fired rooftop unit is supplied by a circuit with a 60 A breaker. The gas piping is likely to become energized by that unit.
- Pick the table. Gas piping is “other metal piping,” so use Table 250.122.
- Enter with the circuit rating. 60 A.
- Read the size. The 60 A row gives 10 AWG copper (NEC Table 250.122). In practice the circuit’s own equipment grounding conductor can serve as this bond.
Worked example 2: structural steel
A building’s interconnected structural steel is exposed and likely to become energized. The service conductors are 600 kcmil copper.
- Pick the table. Structural metal uses Table 250.102(C)(1).
- Find the row. 600 kcmil is in the “over 350 through 600 kcmil” copper row.
- Read the size. That row gives 1/0 AWG copper (NEC Table 250.102(C)(1)).
Check yourself
- Gas piping may be energized by a circuit protected at 200 A. Which table, and what size? Table 250.122, 6 AWG copper.
- Can a standard locknut alone bond a service raceway at a concentric knockout? No. Use a bonding jumper or another permitted method.
- How many intersystem bonding conductors must the termination accept at minimum? Three.
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Find the bonding sections faster on exam day
NFPA 70, National Electrical Code, 2026 Edition (softcover). Mark Table 250.122 in one color and Table 250.102(C)(1) in another, then write the matching color next to each part of 250.104, so the table choice is made before you start reading. The Texas exam is open book. PSI allows a soft-bound NEC with highlighting, underlining and notes made in advance. Loose-leaf, spiral-bound and ring-bound copies are not allowed, and only permanent index tabs made or supplied by the NEC publisher are permitted; homemade and third-party tabs are not.
FAQ
How is gas piping bonded under the NEC?
Under 250.104(B), gas piping likely to become energized is bonded to the equipment grounding conductor of the circuit that could energize it or another permitted point, with a jumper sized from Table 250.122 by that circuit’s rating.
What table sizes the bonding jumper for structural steel?
Table 250.102(C)(1), based on the service or supply conductors.
Why do concentric knockouts need bonding jumpers at the service?
The rings can loosen and break the bonding path, so 250.92(B) requires a permitted bonding method around them instead of standard locknuts alone.
What is an intersystem bonding termination?
A device outside the enclosures, at the service or at a feeder-supplied building disconnect, with terminals for at least three bonding conductors from communications systems.
Are bonding rules on the Texas Journeyman exam?
PSI lists grounding and bonding in Services, Service Equipment and Separately Derived Systems: 6 scored NEC Knowledge questions and 4 scored Calculations questions.
Sources checked October 2026
- PSI Candidate Information Bulletin, Texas electrician examinations (updated September 15, 2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- NFPA 70, National Electrical Code, 2026 Edition, 250.92, 250.94, 250.97, 250.102, 250.104, Table 250.102(C)(1) and Table 250.122
