Short answer: Every ungrounded service conductor needs overload protection from an overcurrent device in series with it (NEC 230.90), and that device is part of the service disconnecting means or located right next to it (NEC 230.91). The device rating is normally not higher than the conductor ampacity, but when two to six circuit breakers or sets of fuses serve as the protection, their ratings may add up to more than the conductor ampacity as long as the calculated load does not. For AC services, ground-fault protection of equipment (GFPE) is required (NEC 230.95) on each service disconnect rated 1000 amperes or more when the system is solidly grounded wye, more than 150 volts to ground and not more than 1000 volts phase to phase. In practice that means 480Y/277 V services with a 1000 A or larger disconnect. The 2026 edition also requires GFPE for solidly grounded DC services of more than 150 volts to ground and not more than 1500 volts DC line to line, again for each service disconnect rated 1000 amperes or more.
PSI lists Services, Service Equipment and Separately Derived Systems (6 scored NEC Knowledge and 4 scored Calculations questions) as a subject area of the Texas Journeyman exam, and names service equipment in it. PSI does not name 230.95 or say how many questions cover GFPE. 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.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain the ideas in our own words and do not reproduce NEC text. Check every rule and table value in your own 2026 NEC, and follow your supervisor and the local inspector.
Where this fits
The services and overcurrent protection page covers service disconnects, splices in service conductors and the general overcurrent rules of Article 240. This page is the next layer in Part VII of Article 230: what the service overcurrent device must protect, where it sits, and the conditions that decide whether a service needs GFPE.
230.90: what the service overcurrent device protects
- Each ungrounded conductor. Every ungrounded service conductor has an overcurrent device in series with it. The grounded conductor does not get an overcurrent device unless the device opens all conductors of the circuit at the same time.
- Rating not above ampacity. The device rating or setting is not higher than the allowable ampacity of the conductors, with listed exceptions.
- The main exceptions to remember:
– Motor starting current, sized under the motor rules. – Fire pump supply conductors, which follow the fire pump article. – The next higher standard rating rule of 240.4(B), where its conditions are met. – Two to six devices. When two to six circuit breakers or sets of fuses act as the overcurrent protection, the sum of their ratings may exceed the conductor ampacity, as long as the calculated load does not exceed it.
Worked example: six breakers on one set of service conductors
Service entrance conductors have an allowable ampacity of 200 A. The calculated load is 185 A. The service has six breakers acting as the service disconnects: 100 A, 60 A, 60 A, 40 A, 30 A and 30 A.
- Sum of ratings. 100 + 60 + 60 + 40 + 30 + 30 = 320 A.
- Compare the load, not the sum. 185 A calculated load is not more than the 200 A conductor ampacity.
- Result. The 320 A combined rating is allowed by the 230.90(A) exception, because the 185 A calculated load is within the 200 A conductor ampacity. That settles this one rule; the installation still has to meet the other service disconnect and equipment requirements.
230.91: where the device goes
The service overcurrent device is an integral part of the service disconnecting means or is located immediately adjacent to it. A main breaker in a panelboard used as service equipment meets this because the disconnect and the overcurrent device are the same device.
230.95: does this service need GFPE?
In the 2026 NEC, 230.95 covers two kinds of service. For a solidly grounded wye AC service, GFPE is required when all four are true:
- The system is solidly grounded wye.
- The voltage to ground is more than 150 V.
- The phase to phase voltage is not more than 1000 V.
- The service disconnect is rated 1000 A or more. The rating is the largest fuse that fits the switch, or the highest continuous current trip setting the breaker is rated for or can be adjusted to.
For a solidly grounded DC service, the 2026 edition requires GFPE on each service disconnect rated 1000 A or more when the system is more than 150 V to ground and not more than 1500 V DC line to line.
| Service | GFPE at a 1200 A disconnect? | Why |
|---|---|---|
| 120/240 V single phase | No | 120 V to ground |
| 208Y/120 V | No | 120 V to ground |
| 480Y/277 V | Yes | Wye, 277 V to ground |
| 240/120 V high-leg delta | No | Not a wye system |
| 480 V corner grounded delta | No | Not a wye system |
Settings. The maximum setting of the ground-fault protection is 1200 A, and the maximum time delay is one second for ground-fault currents of 3000 A or more.
Testing. The GFPE system is performance tested when first installed on site by a qualified person using primary current injection, following the instructions provided with the equipment, and a written record of the test is made available to the authority having jurisdiction.
Not required:
- A continuous industrial process where a nonorderly shutdown would add hazards.
- Fire pumps.
Feeders have a matching GFPE rule in Article 215 (NEC 215.10).
Worked example: six disconnects at 480Y/277 V
A 480Y/277 V service has a 2000 A calculated load and uses three service disconnects rated 800 A, 800 A and 600 A.
- System test. Solidly grounded wye, 277 V to ground, 480 V phase to phase: the system meets the voltage conditions.
- Each disconnect. 800 A, 800 A and 600 A are each below 1000 A.
- Result. None of the three disconnects reaches the 1000 A threshold, so none needs GFPE under 230.95. Each disconnect is checked on its own rating; the ratings are not added together. If any one of them were 1000 A or larger, that one would need it. The service still has to meet the other disconnect and equipment requirements.
Check yourself
- Which service needs GFPE at a 1200 A main: 208Y/120 V or 480Y/277 V? 480Y/277 V.
- What is the maximum ground-fault setting? 1200 A.
- With six service breakers, what must not exceed the conductor ampacity? The calculated load.
- Where does the service overcurrent device go? Part of the service disconnect, or immediately next to it.
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Write the GFPE test on one line
NFPA 70, National Electrical Code, 2026 Edition (softcover). Next to 230.95, write “wye + over 150 V to ground + 1000 A or more each disconnect” so the four conditions are one glance. 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
Which services need ground-fault protection of equipment?
Each service disconnect rated 1000 A or more on a solidly grounded wye AC service of more than 150 V to ground and not more than 1000 V phase to phase. The 2026 edition adds solidly grounded DC services of more than 150 V to ground and not more than 1500 V DC line to line, also at 1000 A or more per disconnect.
Does a 208Y/120 V service need GFPE?
No. It has only 120 V to ground.
What is the maximum GFPE setting?
1200 A, with a maximum time delay of one second for ground-fault currents of 3000 A or more.
Can six service breakers add up to more than the service conductor ampacity?
Yes, when two to six breakers or sets of fuses are the overcurrent protection and the calculated load does not exceed the conductor ampacity.
Does GFPE need testing?
Yes. It is performance tested by a qualified person using primary current injection when first installed on site, and a written record is made available to the authority having jurisdiction.
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, Articles 215 and 230
- Electrical Contractor magazine, Ground-Fault Protection Systems for Services (2026 NEC DC service addition): https://www.ecmag.com/magazine/articles/article-detail/systems-ground-fault-protection-systems-services
