Service Equipment for Apprentices (2026 NEC): Meter, Main Disconnect, Panel and Neutral-to-Ground Bonding

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. The Texas exam uses the 2026 NEC, but the code edition enforced on a real job depends on the local jurisdiction and its amendments, so follow your supervisor, the utility and the local inspector on the job.

The path from the utility to your first breaker

A typical utility-supplied house follows the path below. Real installations vary with the utility’s rules and how the equipment is combined, but learn the order and the names, because exam questions and inspectors both use them.

1. Utility supply. Overhead (a service drop) or underground (a service lateral). The service point marks where the serving utility’s facilities connect to the premises wiring, and the utility sets where it is. Who owns and maintains each piece of equipment depends on the utility’s service rules.
2. Service-entrance conductors. The conductors from the service point to the terminals of the service equipment. They are on the supply side of the service overcurrent protection. For one- and two-family dwellings, the 2026 NEC puts the service disconnect outdoors, on the dwelling or within sight of it, as covered below. For other buildings, it may be outside or inside nearest the point where the service conductors enter. Local rules can add limits, and the NEC does not set one national maximum length for any indoor portion.
3. Meter base. Depending on the installation, the service-entrance conductors may pass through the meter base on the way to the service disconnect. The meter measures energy use and is not service equipment by itself. The utility sets its own meter rules, including who supplies the base. Check the utility’s service manual before rough-in.
4. Service disconnecting means. The switch or circuit breaker that disconnects the building wiring from the service conductors. Many houses have a single main breaker; the NEC also permits some arrangements with more than one service disconnect. Article 230 covers how many you may have and where they go.
5. Service panelboard. Often the same enclosure as the main breaker, and then it is where the neutral is bonded to the enclosure. When the service disconnect sits in a separate enclosure outside, the panel inside is fed by a feeder and keeps its neutral isolated. The grounding electrode conductor connects at a location Article 250 permits.
6. Feeders and branch circuits. On the load side of the service disconnect, feeders carry power to panels and other distribution equipment, and branch circuits run from the final overcurrent device to outlets and equipment. Some branch circuits start right in the service panel.

What counts as service equipment

Service equipment is the equipment connected to the load end of the service conductors that serves as the main control and cutoff of the supply. It generally includes the service disconnect, its overcurrent protection and related accessories, whether they sit in separate enclosures or in one combined unit. Together they are the main control and cutoff of the utility supply. A meter base is not service equipment. A subpanel in the garage is not service equipment. The main breaker panel next to the meter usually is.

Part	Service equipment?	Neutral bonded to the can?
Meter base	No	On the supply side of the service disconnect, the NEC permits the neutral to be bonded to the meter enclosure, subject to the utility’s rules. This is not the same as bonding in a feeder panel
Main breaker panel containing the service disconnect	Yes	Yes, through the main bonding jumper, for a typical grounded service
Outdoor main disconnect, with the panel inside	The disconnect is	Yes, in the disconnect enclosure
Panel inside after an outdoor main	No, it is fed by a feeder	No, neutral and ground on separate bars
Garage or shop subpanel	No	No

Where neutral meets ground: the main bonding jumper

In a typical grounded 120/240 V utility service, a main bonding jumper connects the grounded service conductor (the neutral) to the service equipment enclosure and the equipment grounding system (NEC 250.24(C)). Where the NEC permits more than one service disconnect enclosure, the bonding follows the Article 250 rules for that arrangement. That bond connects the equipment grounding path to the grounded service conductor. It helps provide a low-impedance path for ground-fault current back to the source, so an overcurrent device can operate. Separately derived systems, such as a transformer that creates a new neutral, have their own bonding point.

In a typical utility-supplied installation, the neutral is isolated from equipment grounding conductors and enclosures on the load side of the service disconnect. Separately derived systems and other arrangements the NEC permits have their own bonding rules. In a typical feeder-supplied subpanel that means:

• The neutral bar is isolated from the enclosure. Do not install the neutral bonding screw or strap in a feeder-supplied panel, and follow the panel maker’s instructions for any bonding hardware that came installed.
• Equipment grounding conductors land on a separate ground bar bonded to the can.
• A 120/240 V feeder that serves both 120 V and 240 V loads brings two ungrounded conductors, a neutral and an equipment grounding path. In a cable feeder that path is a separate equipment grounding conductor; some metal raceways qualify as the grounding path.

If the neutral is also bonded in a feeder-supplied subpanel, normal neutral current can split between the neutral and parallel paths such as equipment grounding conductors, metal raceways and connected metal piping. A standard overcurrent device usually does not trip, because this is normal load current taking an unintended parallel path, so metal parts can carry current during ordinary operation.

Grounding electrode conductor and electrodes

In a typical grounded service, the grounding electrode conductor connects the service grounded conductor (the neutral) to the grounding electrode system at a point Article 250 permits. It is not meant to carry normal neutral current or to serve as the fault current return path. That system can include qualifying metal underground water pipe, the concrete-encased electrode in the footing, ground rods and other electrodes the NEC recognizes. Qualifying electrodes present at the building generally have to be bonded together into one system, not picked from a menu. The earth is not the fault current path; the metal bonding and equipment grounding paths do that job. Its size usually comes from a table based on the size of the largest ungrounded service-entrance conductor, or the equivalent area of parallel conductors, and some electrode connections have their own sizing allowances (NEC Table 250.66). Connections to some electrodes, such as a ground rod, have their own size limits, so check those rules before you pull wire. For the mistakes inspectors see most, read our grounding and bonding guide.

Disconnect count, location and dwelling rules

• Location. For one- and two-family dwellings, the 2026 NEC puts the service disconnect at a readily accessible outdoor location, on the dwelling or within sight of it (NEC 230.70(A)(1)). For other buildings, it goes in a readily accessible place, outside or inside nearest the point where the service conductors enter.
• How many. A service generally has one disconnect, and the NEC allows up to six only in specific arrangements (NEC 230.71). Do not assume six breakers can be grouped in any enclosure; look up the permitted arrangements in your 2026 NEC.
• One-family dwelling rating. The service disconnect for a one-family dwelling must be rated at least 100 A (NEC 230.79(C)).
• Emergency disconnect marking. For one- and two-family dwellings, the outdoor service disconnect also serves as the emergency disconnect. It must carry the required EMERGENCY DISCONNECT marking (NEC 230.70(B)); check the 2026 NEC marking provisions for the exact placement and appearance. The disconnect still has to be identified as the service disconnect too, so check both marking rules in your 2026 book. Service disconnects for other buildings are marked SERVICE DISCONNECT.
• Remote service equipment. When the service equipment sits away from the house, such as at the property line or along a road, the service disconnect remains at that equipment. The house is then fed by a feeder, and the 2026 NEC generally requires an outdoor, readily accessible emergency disconnect on the dwelling or within sight of it, which means in view and not more than 50 ft away, with limited exceptions (NEC 225.41). That feeder emergency disconnect does not become the service disconnect. Read the 2026 wording of 230.70 and 225.41 before you plan the layout.
• Surge protection. Dwelling services need a surge-protective device (NEC 230.67).

Worked example: sizing a service by load

Some exam problems give you a finished service load calculation and ask for the service rating. The example below assumes the load was already calculated under the NEC rules. It does not do the dwelling load calculation or size the conductors.

A house has a calculated load of 27,600 VA on a 120/240 V single-phase service.

1. Amperes = 27,600 ÷ 240 = 115 A.
2. A 125 A rating is the next standard overcurrent device rating in 240.6(A) above the 115 A calculated load, so it is a suitable candidate in this simplified example. The service conductors, equipment ratings and any dwelling-specific minimums, such as the 100 A rule above, still have to be checked before you pick real equipment.
3. Check: 125 × 240 = 30,000 VA, which is at least 27,600 VA.
4. Check the floor: a one-family dwelling service disconnect must be at least 100 A, and 125 A clears it.

This example finds the service rating from the calculated load. Conductor size is a separate step that comes from the ampacity rules, so do not stop at the breaker number on a real job.

The 2026 NEC moved branch-circuit, feeder and service load calculations from Article 220 to a new Article 120. Find Article 120 in your book before exam day.

Check yourself

1. In a typical house where the main breaker panel contains the service disconnect, which panel has the main neutral-to-ground bond: that main panel or a feeder-supplied garage subpanel? The main panel containing the service disconnect.
2. A 120/240 V feeder to a subpanel serves both 120 V and 240 V loads. What does it bring? Two ungrounded conductors, a neutral and an equipment grounding path.
3. A calculated load is 27,600 VA at 240 V. What is the current? 115 A.

FAQ

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 225, 230 and 250
• IAEI Magazine, NEC 2026 significant code changes: https://iaeimagazine.org/standards/nec-2026-significant-code-changes/