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Services

20 original questions. The keyed answer, the article to open, and a short explanation are on the page. Confirm the section in your NEC 2026 book. These items are a sample. The rest of this topic stays in the practice app.

All free sections·Study notes·20-question practice test

1 · Services · NEC Knowledge
A note in your study set says the service disconnect has to be readily accessible and grouped near the point where the service conductors enter. In plain language, what is that rule trying to make possible?
1. A. Reading the meter from the sidewalk without entering the property
2. B. Opening the building supply without walking through a large part of the structureKeyed answer
3. C. Omitting the equipment grounding conductor on the feeder
4. D. Putting each branch breaker in its own building
Readily accessible means a person can reach the disconnect and operate it without a ladder, a tool, or a climb over obstacles. Grouping the handles keeps that shutoff in one place. The location language is in Article 230. Confirm the section in your NEC 2026 book.
Open NEC 2026 230.70
2 · Services · NEC Knowledge
The calculated service load is 180 A. The plan puts the only service overcurrent device on a utility pole 80 ft away and lands the house on main lugs, with no overcurrent at the house. What is wrong with that?
1. A. Service overcurrent protection belongs at the load end of the service conductors, with the service disconnect, not only at a pole down the street.Keyed answer
2. B. Main-lug equipment is forbidden in every building.
3. C. The pole device is enough if the conductors are copper.
4. D. Overcurrent protection is required only on the grounded conductor.
Article 230 places the service disconnect and the service overcurrent protection at the load end of the service conductors. A device at the utility pole does not replace that. Confirm the location in NEC 2026 before you leave the house on unprotected main lugs.
Open NEC 2026 Article 230
3 · Services · NEC Knowledge
A new one-family dwelling service is installed with no surge-protective device. The helper says surge protection is still only a recommendation in an informational note. What does this new dwelling service need?
1. A. A listed surge-protective device at the service. On a new dwelling service, NEC 2026 makes that device a requirement.Keyed answer
2. B. Surge protection is prohibited on a dwelling service.
3. C. A surge device is required only on services over 400 A.
4. D. The meter is the surge-protective device, so nothing else is installed.
Article 230 requires a listed surge-protective device for a new dwelling service. An older habit of treating that device as optional does not match the 2026 rule, and existing services are a different question from a new one. Confirm the section in NEC 2026.
Open NEC 2026 230.67
4 · Services · NEC Knowledge
The service disconnect for a house sits on an outside wall with no roof over it, so rain hits the enclosure. What has to be true of that enclosure?
1. A. It has to be suitable for a wet location.Keyed answer
2. B. The meter socket takes the place of a weatherproof enclosure.
3. C. A wood cabinet is acceptable if the door shuts.
4. D. Any indoor panel is acceptable if the breakers are new.
Rain on the enclosure makes this a wet-location service installation. Article 230 covers the service equipment, and an indoor-only box is the wrong piece of equipment for that wall. Confirm the enclosure rules in NEC 2026 Article 230.
Open NEC 2026 Article 230
5 · Services · NEC Knowledge
A one-family dwelling has its only service disconnect in an interior closet. The study task is the outdoor emergency disconnect used to shut the house off from outside. What is wrong with this arrangement?
1. A. The meter is the emergency disconnect, so no switch is required.
2. B. An interior closet is the required place for the emergency disconnect.
3. C. Emergency disconnects are required only for commercial kitchens.
4. D. The only handle is inside, so there is no outdoor emergency disconnect.Keyed answer
Article 230 includes the dwelling emergency disconnect so the building can be shut off from outside. A closet on an interior hall does not do that job. Confirm the location and marking rules in NEC 2026 Article 230.
Open NEC 2026 Article 230
6 · Services · NEC Knowledge
In a service raceway the grounded conductor has the same black insulation as the ungrounded conductors, with no white, gray, or other marking. A helper says color does not matter at a service because the lugs are marked. What has to happen?
1. A. The grounded conductor has to be identified so it is not used as an ungrounded conductor. Same-color insulation with no marking is not an identification.Keyed answer
2. B. Only equipment grounding conductors are identified. Grounded conductors may match the phase colors.
3. C. Identification is required only on 480 V systems.
4. D. Painting the outside of the conduit green identifies the grounded conductor inside it.
Article 200 covers identification of the grounded conductor, and Article 230 applies that idea to the service conductors. Marked lugs do not identify the conductor in the raceway. Confirm both articles in NEC 2026 before you land an unmarked black conductor on the neutral bar.
Open NEC 2026 Articles 200 and 230
7 · Services · NEC Knowledge
The service equipment is marked with a short-circuit current rating of 10,000 A. The utility letter says the available fault current is 22,000 A. What is the problem?
1. A. Every branch breaker must be replaced with a 15 A device.
2. B. The neutral is larger than the ungrounded conductors.
3. C. The equipment rating is below the fault current the utility can deliver.Keyed answer
4. D. The meter has to move to the other side of the house.
Service equipment has to withstand the fault current available at its terminals. A 10,000 A marking against 22,000 A available does not do that. Article 110 covers the rating comparison, and Article 230 covers the service equipment. Confirm both in NEC 2026.
Open NEC 2026 Article 110
8 · Services · NEC Knowledge
The utility conductors end at the service point on the side of the house. From that point to the service disconnect, the conductors are in a raceway the electrician installed. A helper treats them as still utility-owned and skips the service rules. What are those conductors?
1. A. Branch-circuit conductors, because they are on the building.
2. B. Feeder conductors, because they are past the meter socket.
3. C. Utility conductors for their whole length, so the NEC never applies.
4. D. Service-entrance conductors. Premises wiring, and the service rules, start at the service point.Keyed answer
Article 100 names the service point as the handoff from the utility. The conductors the electrician installs from that point to the service disconnect are service-entrance conductors under Article 230. Confirm both the definition and the service article in NEC 2026.
Open NEC 2026 Article 230
9 · Services · NEC Knowledge
A panelboard used as service equipment has bare ungrounded terminals on the line side of the main breaker. A helper leaves them exposed inside the enclosure because only electricians open the door. What is required over those terminals?
1. A. A barrier so those energized line terminals are guarded when the cover is off and someone is working the branch breakers.Keyed answer
2. B. A barrier is required only over the grounded conductor.
3. C. Removing the deadfront is the barrier.
4. D. Line-side service terminals may stay open if the panel is indoors.
Article 230 requires a barrier over the ungrounded service terminals so that working in the panel does not put a hand on the always-energized line side. The door is not that barrier. Confirm the service-equipment rule in NEC 2026.
Open NEC 2026 230.62
10 · Services · NEC Knowledge
Someone operates the service disconnect. Which conductors is that switch or breaker there to open?
1. A. Only the grounded conductor, leaving the ungrounded conductors closed.
2. B. Only the grounding electrode conductor.
3. C. Only the equipment grounding conductor.
4. D. The ungrounded service conductors.Keyed answer
The service disconnect opens the ungrounded conductors so the building can be shut off. It is not there to switch the grounding electrode conductor. Confirm what the service disconnecting means must open in NEC 2026 Article 230.
Open NEC 2026 Article 230
11 · Services · NEC Knowledge
The calculated service load is 140 A. The service disconnect on the wall is rated 125 A. What is wrong with that disconnect for this load?
1. A. The calculated load sizes only the grounding electrode, not the disconnect.
2. B. Its rating is below the calculated load.Keyed answer
3. C. The disconnect is too large and must be replaced with a 60 A device.
4. D. A disconnect must be rated exactly half the calculated load.
The service disconnect has to be rated for the load it supplies. A 125 A device under a 140 A calculated load does not meet that. Article 230 also has a dwelling minimum you confirm in the book. The 140 A and 125 A figures are the comparison in this item.
Open NEC 2026 Article 230
12 · Services · NEC Knowledge
A one-family dwelling's outdoor service disconnect is on the side wall, but a locked gate is the only way to reach it and the fire department does not have the key. The helper says outdoors is enough. What fails?
1. A. A locked gate is the preferred location, because it keeps the public off the disconnect.
2. B. Readily accessible only applies to the meter, not the service disconnect.
3. C. The disconnect is outdoors, but it is not readily accessible if a locked gate blocks it. The dwelling emergency disconnect has to be reachable without hunting for a key.Keyed answer
4. D. Move the disconnect into the attic so the gate no longer matters.
Article 230 wants the one- or two-family dwelling service disconnect readily accessible outdoors so it can also serve as the emergency disconnect. A lock the responders cannot open fails that reach. Confirm the location rule in NEC 2026.
Open NEC 2026 Article 230
13 · Services · NEC Knowledge
An outdoor dwelling disconnect is mounted so the handle is 7 ft above the standing surface and you need a ladder to reach it. The helper says height does not matter because the box is outside. What is the miss?
1. A. Outside is not the whole test. A disconnect you can reach only with a ladder is not readily accessible.Keyed answer
2. B. Seven feet is the required height for every service disconnect.
3. C. A ladder stored next to the house makes the disconnect readily accessible.
4. D. Readily accessible means the meter reader can see the glass, not that a person can operate the handle.
Readily accessible means a person can reach and operate the disconnect without a ladder, a tool, or climbing over an obstacle. Article 230 applies that idea to the dwelling emergency disconnect. Confirm the definition and the location section in NEC 2026.
Open NEC 2026 Article 230
14 · Services · NEC Knowledge
The outdoor dwelling disconnect is installed, but the cover is blank and nothing outside says this handle shuts the house off. The helper says labeling is optional if the box is next to the meter. What is missing?
1. A. Only the utility may apply a label, and only on the meter.
2. B. Marking is required only when there are two to six disconnects.
3. C. The emergency disconnect has to be marked so a responder can tell what the handle does. A blank cover next to a meter is not that marking.Keyed answer
4. D. Paint the grounded conductor green and skip the label.
Article 230 includes identification of the dwelling emergency disconnect. Location without a marking still leaves a responder guessing. Confirm the marking text in NEC 2026 rather than inventing a sticker.
Open NEC 2026 Article 230
15 · Services · Calculations
A service carries 35 A of noncontinuous load and 40 A of continuous load. For this drill, minimum service-conductor ampacity is the noncontinuous load plus 125% of the continuous load. What ampacity do you need?
1. A. 75 A
2. B. 85 AKeyed answer
3. C. 94 A
4. D. 100 A
40 × 1.25 = 50 A. Add the 35 A noncontinuous load to get 85 A. Applying 125% to both parts is the path that lands near 94 A. Confirm continuous-load sizing for service conductors in NEC 2026 Article 230.
Open NEC 2026 Article 230
16 · Services · Calculations
After demand, a dwelling calculation stands at 12,000 VA of general load. Two 240 V air-conditioning units are then added at 3,600 VA each, and the problem says to add both at 100%. What is the service current at 240 V?
1. A. 50 A
2. B. 65 A
3. C. 77 A
4. D. 80 AKeyed answer
12,000 + 3,600 + 3,600 = 19,200 VA. 19,200 / 240 = 80 A. Leaving one air conditioner out, or dividing by 120, produces the other choices. The 12,000 VA came from Article 120 demand steps. The service that carries the total is Article 230.
Open NEC 2026 Articles 120 and 230
17 · Services · Calculations
A service carries 50 A of noncontinuous load and 32 A of continuous load. For this drill, minimum service-conductor ampacity is the noncontinuous load plus 125% of the continuous load. What ampacity do you need?
1. A. 102 A
2. B. 115 A
3. C. 90 AKeyed answer
4. D. 82 A
32 × 1.25 = 40 A. Add the 50 A noncontinuous load to get 90 A. Putting 125% on both loads overstates the drill. Confirm the split in NEC 2026 Article 230. Both currents and the factor are printed in the stem.
Open NEC 2026 Article 230
18 · Services · Calculations
This drill allows no more than 6 service-disconnect handles in one group. The equipment already has 4 handles. How many additional handles can be added without passing the drill limit?
1. A. 1 handle
2. B. 6 handles
3. C. 4 handles
4. D. 2 handlesKeyed answer
6 − 4 = 2 handles left in the group. Article 230 is where the real limit on service-disconnect handles is read. The 6-handle figure is this drill's number, printed so the subtraction does not depend on memory.
Open NEC 2026 Article 230
19 · Services · Calculations
A service has 46 A of noncontinuous load and 24 A of continuous load. For this drill, required ampacity is the noncontinuous load plus 125% of the continuous load. Standard ratings you may use: 70, 80, 90, and 100. What is the smallest rating that is at least that ampacity?
1. A. 100 A
2. B. 80 AKeyed answer
3. C. 76 A
4. D. 70 A
24 × 1.25 = 30 A, and 46 + 30 = 76 A. The smallest listed rating that is at least 76 A is 80 A. A 70 A device is under the required ampacity. Confirm the service sizing rule in NEC 2026 Article 230.
Open NEC 2026 Article 230
20 · Services · Calculations
A hillside house service is 120/240 V. The problem gives 9,600 VA of noncontinuous load and 9,600 VA of continuous load. Minimum service ampacity is (noncontinuous VA + 125% of continuous VA) / 240. What current do you get?
1. A. 80 A
2. B. 90 AKeyed answer
3. C. 100 A
4. D. 180 A
9,600 × 1.25 = 12,000 VA. Add 9,600 VA to get 21,600 VA. 21,600 / 240 = 90 A. Skipping the 125% gives 80 A. Putting 125% on both loads gives 100 A. Article 120 is the load. Article 230 sizes the service. The factor and the voltage are printed in the stem.
Open NEC 2026 Articles 120 and 230

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