Grounding and Bonding practice questions

Correct: A — 12 AWG

Table 250.122 sizes the equipment grounding conductor from the rating of the overcurrent device ahead of the equipment — not the load or the circuit conductors. For a 20 A device, the minimum copper EGC is 12 AWG. The other options are off by one or more conductor sizes.

Correct: A — The under-50-volt system must be grounded

Per 250.20(A)(2), an under-50-volt system supplied by a transformer must be grounded if the transformer supply system itself is ungrounded. Being under 50 volts doesn't exempt it, the outdoor/overhead condition is a separate independent trigger, and the 150-volts-to-ground condition is another independent trigger — any one of the three conditions in 250.20(A) is enough on its own.

Correct: D — Coloring the insulation green at each termination

Per 250.119(B), conductors 4 AWG and larger that aren't factory-marked green must be identified at each end and every accessible point by stripping the insulation, coloring it green, or applying green tape/labels — encircling the conductor. Black tape doesn't satisfy the green-identification requirement, leaving it unmarked ignores the size-based duty to identify, and marking only the midpoint misses the required end and accessible-point locations.

Correct: B — A ground ring of bare copper conductor sized 2 AWG or larger, encircling the structure

250.52(A)(4) recognizes a ground ring of at least 20 ft of bare copper conductor not smaller than 2 AWG. A water pipe needs 10 ft of earth contact, not 5, to qualify under 250.52(A)(1); a rod electrode must be at least 8 ft long under 250.52(A)(5); underground gas piping systems are excluded as electrodes elsewhere in Article 250, not part of this permitted list.

Correct: A — Routed with the ungrounded conductors to each service disconnecting means and connected to its grounded conductor terminal or bus

250.24(D) requires the grounded conductor to be routed with the ungrounded conductors to each service disconnecting means and landed on each one's grounded conductor terminal or bus. Running it separately, stopping at only one disconnect, or omitting it are all inconsistent with that requirement.

Correct: A — Install individual grounding electrode conductors sized per 250.66 to each of the four disconnecting means

250.64(D)(2) permits an individual, fully sized grounding electrode conductor run to each disconnecting means. Jumpering between enclosures, splicing a shared conductor, or skipping the connection based on ampere rating are not among the three permitted methods in 250.64(D).

Correct: A — Drive the rod at an oblique angle not exceeding 45 degrees from vertical

Per 250.53(A)(4), when rock bottom is encountered, the electrode shall be driven at an oblique angle not to exceed 45 degrees from vertical, or buried in a trench at least 30 in. deep. Cutting the rod short or leaving it under-depth doesn't satisfy the 8 ft soil-contact requirement, and 60 degrees exceeds the allowed angle.

Correct: C — Within the enclosure where it originates, at a single point from source to first disconnect

Per 250.30(A)(1), the system bonding jumper connection is made at one single point — either the source or the first disconnecting means — and it must remain within the enclosure where it originates. Placing a bonding connection at every enclosure would create parallel grounded-conductor paths, which is what the single-point rule prevents.

Correct: A — At any accessible point from the load end of the service conductors to the grounded conductor terminal at the service disconnecting means

250.24(A)(1) permits the GEC connection at any accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral, all the way to the terminal or bus where the grounded service conductor connects at the service disconnecting means. Restricting it to just the meter enclosure or just inside the disconnect enclosure is narrower than the rule allows.

Correct: A — Use Table 250.102(C)(1), based on the largest ungrounded conductor

250.28(D)(1) points to Table 250.102(C)(1) as the sizing table. Table 250.66 is for grounding electrode conductors, not bonding jumpers, and the other two options describe no rule in this concept's sections.

Correct: A — The building disconnecting means enclosure at the garage

250.104(A)(3) permits bonding at a separately supplied building to the building disconnect enclosure, the equipment grounding conductor run with the supply conductors, or a grounding electrode used at that building. The grounded conductor at the original service applies to service equipment under 250.104(A)(1), not to a separately supplied building, and isolating the piping doesn't satisfy the bonding requirement.

Correct: B — A bonding jumper around the impaired connection

250.92(B) specifically calls out reducing washers and oversized, concentric, or eccentric knockouts as impaired connections that require a bonding jumper meeting the article's requirements. A locknut making the mechanical connection does not satisfy the bonding requirement, doubling up locknuts doesn't address the impaired connection, and this section is about bonding continuity, not adding a separate grounding electrode conductor.

Correct: B — 6.0 m (20 ft)

Per 250.52(A)(3), rebar connected by steel tie wires, welding, or other effective means must total at least 6.0 m (20 ft) to qualify as a concrete-encased electrode. The shorter lengths listed don't meet this threshold, and the 1.8 m figure is a ground-rod driving depth, not the concrete-encased electrode length.

Correct: A — None is required, since the tool is double-insulated and distinctively marked

250.114 exempts listed tools, appliances, and equipment covered under list items 2 through 4 from the equipment grounding conductor requirement when protected by double insulation or its equivalent, provided the equipment is distinctively marked. The 'all hand-held tools must be grounded' choice ignores this exemption, the outdoor-use condition isn't part of this exemption, and the guarding exemption applies to motors, not double-insulated tools generally.

Correct: B — The grounded service conductor and the grounding electrode conductor

Per 250.130(A), for grounded systems the EGC connection at service equipment is made by bonding it to both the grounded service conductor and the grounding electrode conductor. Bonding to the grounding electrode conductor alone is the rule for ungrounded systems under 250.130(B), not grounded systems.

Correct: D — So that removing the first receptacle does not interrupt ground-fault current path continuity to the downstream receptacle

250.148(B) requires the grounding connections to be arranged so that removing a luminaire, receptacle, or other device does not interrupt the equipment grounding conductor's continuity to whatever else the box feeds. This applies regardless of box material, and applies whether or not the device is currently installed.

Correct: A — Connecting to an equipment grounding conductor of the wire type run with the circuit conductors

250.134(2) permits connecting to a wire-type equipment grounding conductor run with the circuit conductors. Grounding to the grounded circuit conductor is only allowed in the narrow 250.32/250.140/250.142 exceptions, not in all installations, and isolated metal parts don't satisfy the grounding requirement.

Correct: A — From Table 250.122 based on the feeder or branch-circuit overcurrent protective device rating

250.122(F)(1)(a) sizes a single wire-type EGC in a shared raceway per Table 250.122, based on the rating of the OCPD protecting the feeder or branch circuit — not divided per raceway and not based on a single parallel conductor's ampacity, which is the confusion this question targets.

Correct: C — It must be increased in size proportionately to the increase in circular mil area of the ungrounded conductors

Per 250.122(B), when ungrounded conductors are increased in size for any reason other than a 310.15(B) or (C) ampacity adjustment — voltage drop is a classic example — the wire-type EGC must be increased proportionately to the circular mil increase. It does not have to match the new conductor size one-for-one, and the proportional bump applies whether or not other circuits share the raceway.

Correct: D — Using Table 250.122(A) based on the maximum permitted dual element time-delay fuse rating per 430.52(C)(1)(a)

Per 250.122(D)(2), when the overcurrent device is an instantaneous-trip circuit breaker or a motor short-circuit protector, the EGC is sized from Table 250.122(A) using the maximum permitted dual element time-delay fuse rating from 430.52(C)(1)(a), not the breaker's own trip setting. Sizing directly off the trip rating is the general-case method under 250.122(D)(1), which doesn't apply here.

Correct: C — The structural metal frame of a building

250.118(B)(2) specifically prohibits using a building's structural metal frame as an equipment grounding conductor. Rigid metal conduit, the copper sheath of Type MI cable, and a bare stranded copper conductor are all recognized EGC types under 250.118(A).

Correct: B — The equipment is located in a wet or damp location and not isolated

250.110(2) lists wet or damp locations without isolation as a trigger condition requiring grounding. The wood-pole apparatus over 8 ft, double-insulated listed equipment, and permanently insulated heater frames are all specific exemptions from the grounding requirement, not triggers for it.

Correct: D — A listed irreversible compression connector rated for grounding and bonding

250.64(C)(1) permits splicing a wire-type grounding electrode conductor only by irreversible compression-type connectors listed as grounding and bonding equipment, or by exothermic welding. A reversible mechanical splice, a twist-on connector, and soldering wire-type conductors are not among the permitted methods.

Correct: C — No, only industrial, commercial, or institutional buildings with qualified maintenance and an exposed run qualify beyond 5 ft

Per 250.68(C)(1), interior metal water piping beyond 5 ft from the point of entrance cannot be used to interconnect electrodes unless the building is industrial, commercial, or institutional with qualified maintenance and the entire pipe run used is exposed. A dwelling unit doesn't meet that carve-out, so the exposed-run-with-qualified-maintenance option doesn't apply, and the blanket 'never' option is also wrong since the exception exists for qualifying buildings.

Correct: A — It must be protected in RMC, IMC, Schedule 80 PVC, RTRC-XW, EMT, or cable armor because it is smaller than 6 AWG

Per 250.64(B)(3), grounding electrode conductors smaller than 6 AWG must be protected in RMC, IMC, Schedule 80 PVC, RTRC-XW, EMT, or cable armor no matter what — the 'not exposed to physical damage' exemption for bare installation in 250.64(B)(1) only applies to 6 AWG or larger conductors.

Correct: D — 6 AWG copper

Per 250.66(A), a GEC connected only to a rod, pipe, or plate electrode need not be larger than 6 AWG copper (or 4 AWG aluminum). The 4 AWG copper option is the cap for a concrete-encased electrode under 250.66(B), not a rod electrode. Sizing per Table 250.66 based on service conductors is the general rule this exception overrides.

Correct: A — The earth's impedance is too high to reliably clear a fault, so it cannot serve as the effective ground-fault current path.

250.4(A) requires a low-impedance effective ground-fault current path back to the source, and explicitly states the earth cannot serve as that path — its impedance is far too high to open the overcurrent device quickly. The rod-spacing and system-type distractors describe real installation details from elsewhere in Article 250, but they aren't why an earth-only path fails here.

Correct: C — Within the enclosure of the service disconnecting means

250.142(A) permits connecting the grounded circuit conductor to equipment on the supply side of, or within the enclosure of, the ac service disconnecting means. A downstream panelboard, a load-side MCC frame, and a branch-circuit junction box are all load-side locations, which 250.142(B) prohibits absent one of its narrow exceptions.

Correct: B — The earth is not permitted to be considered an effective ground-fault current path

250.4(A)(5) explicitly states the earth shall not be considered an effective ground-fault current path — earth resistance is far too high to clear a fault fast. A low-impedance metallic bonding path back to the source is required. The other choices describe rules that don't exist in this section.

Correct: C — Ground detectors must be installed on the system

250.36 requires ground detectors to be installed, along with qualified-persons-only maintenance and zero line-to-neutral loads — not a reduced line-to-neutral load, not a solid backup ground, and not a specific annual AHJ inspection cycle.

Correct: D — Ground detectors are installed on the system

250.187 requires ground detectors, qualified-persons-only maintenance, and no line-to-neutral loads. A solid neutral-to-ground connection violates 250.187(C), which allows grounding only through the impedance device, and a bare conductor in a readily accessible location violates 250.187(B).

Correct: B — 6 ft (1.8 m)

Per 250.102(E)(2), a bonding jumper or equipment bonding jumper installed outside a raceway or enclosure cannot exceed 1.8 m (6 ft) and must be routed with the raceway. The 3 ft and 10 ft options are fabricated thresholds, and there is no unlimited-length allowance outside the outside-pole exception.

Correct: D — The generator only supplies equipment mounted on it or cord-and-plug equipment through its own receptacles, with all equipment grounding conductor terminals bonded to the frame

250.34(A) ties the exception to what the generator supplies (only its own mounted or cord-and-plug equipment) plus bonding all equipment grounding conductor terminals and metal parts to the frame — not to generator size, location, or an automatic neutral bond. Bonding the grounded conductor is a separate, additional requirement under 250.34(C) that only applies if the unit is a separately derived system.

Correct: B — Connected to an equipment grounding conductor per 250.134 or 250.138

Per 250.140(A), new circuits supplying ranges must include an equipment grounding conductor, and the frame connects to it per 250.134 or 250.138. The neutral-bonding method is not an option for new installations — it's restricted to existing installations under 250.140(B).

Correct: B — An equipment bonding jumper sized per Table 250.122

Per 250.146, the default requirement is an equipment bonding jumper sized to Table 250.122. Metal-to-metal contact is the surface-mount exception under 250.146(A), and mounting screws alone only satisfy bonding when the yoke is specifically listed as self-grounding per 250.146(B) — not for an ordinary yoke.

Correct: D — It must be run with the feeder and connected to the garage disconnect and grounding electrode(s), kept separate from the grounded conductor

250.32(B)(1) requires an equipment grounding conductor run with the supply conductors, connected to the disconnecting means and grounding electrode(s), with no connection to the grounded conductor. There's no ampacity threshold or electrode-based exemption for running the EGC.

Correct: C — Base it on the total circular mil area of the parallel ungrounded conductors, but not smaller than 1/0 AWG

Per 250.186(A)(2), when ungrounded service-entrance conductors run in parallel in two or more raceways, the grounded conductors must also run in parallel, sized from the total circular mil area of all the parallel ungrounded conductors per 250.186(A)(1), but never smaller than 1/0 AWG. Sizing off ampacity alone applies to delta services under 250.186(A)(3), not parallel raceways, and sizing each raceway in isolation ignores the total circular mil area requirement.

Correct: C — A multigrounded neutral system with an equipment grounding conductor connected to the multigrounded neutral conductor at the source

250.184(B)(1) permits a single-point grounded neutral system to be fed only from a separately derived system or from a multigrounded neutral system where an equipment grounding conductor is connected to the multigrounded neutral at the source. Without that EGC bond at the source, a multigrounded system doesn't qualify, and ungrounded or grounded-at-every-disconnect setups aren't single-point grounded systems at all.

Correct: B — From Table 250.102(C)(1), based on the largest ungrounded supply conductor in the raceway

250.102(C)(1) sizes the supply-side bonding jumper directly from Table 250.102(C)(1) using the largest ungrounded supply conductor in the raceway or cable. Table 250.66 sizes grounding electrode conductors, and Table 250.122 sizes equipment grounding conductors off overcurrent device rating — both are separate, distinct sizing tables not referenced by this section.

Correct: D — Not less than 33 1/3 percent of the phase conductor ampacity

250.184(A)(2) sets the default floor at 33 1/3 percent of the phase conductor ampacity (and never less than the imposed load). The 20 percent option is a reduced allowance only for industrial and commercial premises under engineering supervision, not the general rule.

Correct: C — Regardless of voltage, except as permitted in 250.112(F) and (I)

250.112 states the listed equipment's exposed metal parts must be grounded regardless of voltage, except as permitted in 250.112(F) and (I). There's no voltage threshold, dwelling-only limitation, or cord-and-plug requirement — this section addresses equipment fastened in place or connected by permanent wiring.

Correct: C — The rod tests at 25 ohms or less resistance to earth

Per 250.53(A)(2), a single rod, pipe, or plate electrode only avoids the supplemental electrode requirement if it tests at 25 ohms or less resistance to earth. Depth, bonding location, and material don't exempt it from the supplemental electrode requirement — those relate to other electrode installation rules, not this exception.

Correct: D — A supplemental electrode of a type specified in 250.52(A)(2) through (A)(8)

Per 250.53(D)(2), a metal underground water pipe electrode must always be supplemented by an additional electrode from 250.52(A)(2) through (A)(8). There's no exception based on contact length with earth, no requirement for a duplicate water pipe electrode, and no utility sign-off requirement in this section.

Correct: A — A separately derived system supplying only rectifiers for adjustable-speed industrial drives

250.21(A)(2) permits (but does not require) separately derived systems used exclusively for rectifiers supplying adjustable-speed industrial drives to be ungrounded. General-purpose feeders, dwelling services, and standard branch circuits are ordinary ac systems that fall under the general grounding requirements, not this exception.

Correct: A — 250.102(A)

250.102(A) lists the permitted materials (copper, aluminum, copper-clad aluminum, or other corrosion-resistant material) and forms (wire, bus, screw, or similar) for bonding jumpers. 250.102(C) instead covers sizing the supply-side bonding jumper, not what it's made of.

Correct: D — From Table 250.122, based on the rating of the circuit likely to energize the piping

250.104(B) requires bonding jumpers and equipment grounding conductors for other metal piping to be sized per Table 250.122, using the rating of the circuit that is likely to energize the piping. Table 250.66 sizes grounding electrode conductors based on service conductors, which is a different calculation used elsewhere in Article 250, not for this bonding jumper.

Correct: C — One of the methods listed for services in 250.92(B), except the locknuts-and-bushing method of 250.92(B)(1)

250.97 requires continuity to be ensured by one or more of the methods specified for services in 250.92(B), specifically excluding (B)(1) — the plain locknuts-and-bushing method is not considered reliable enough above 250 volts to ground. The under-250-volt locknut-and-bushing approach and generic under-300-volt equipment grounding methods don't meet this higher standard.

Correct: D — At the same point where the grounding electrode conductor connects to the system

250.104(D)(1) requires the bonding jumper to metal water piping to connect at the same point on the separately derived system where the grounding electrode conductor is connected. There's no water-meter or 5-foot rule here, and 'first accessible union' isn't the standard — it's tied to the GEC connection point.

Correct: B — The neutral conductor

250.26(2) requires the neutral conductor to be the grounded conductor in a single-phase, 3-wire system. There's no provision letting the installer pick a hot conductor, base the choice on voltage-to-ground, or on conductor size.

Correct: D — At the source or at the first disconnecting means where the system is grounded

250.168 permits the connection at exactly one of two points: the source, or the first disconnecting means where the system is grounded. Bonding at every disconnect, at the grounding electrode alone, or at an arbitrary junction box are not what the section allows.

Correct: B — 250.166(C)

250.166(C) caps the sole-connection portion of the GEC to a rod, pipe, or plate electrode at 6 AWG copper or 4 AWG aluminum. 250.166(D) and (E) set different caps for concrete-encased electrodes and ground rings, and 250.166(B) is the general largest-conductor sizing rule, not the rod-electrode exception.

Correct: C — It must be grounded, since it exceeds 60 volts but not 300 volts

250.162(A) requires grounding for 2-wire dc systems supplying premises wiring when operating at greater than 60 volts but not greater than 300 volts. 120 volts falls in that range, so grounding is required. The other options misstate the threshold or apply the industrial exception too broadly.

Correct: C — At the source of the separately derived system

Per 250.169, when the separately derived system has no disconnecting means or overcurrent devices, the grounding electrode conductor connection shall be made at the source itself. There is no grounded neutral bus to reference since the dc system is ungrounded, and the rule explicitly still requires a GEC for grounding equipment even though the system is ungrounded.

Correct: C — 250.124(A)

250.124(A) requires first-make, last-break of the equipment grounding conductor for separable connections like drawout equipment and attachment plugs, unless interlocks prevent energization without grounding continuity. 250.124(B) instead addresses switches or cutouts in the EGC, not separable/drawout connections.

Correct: B — 250.70

250.70 lists the approved connection methods to the electrode itself (exothermic welding, listed lugs, pressure connectors, clamps). 250.68 instead governs where and how the connection point must be accessible and effective, while 250.66 sizes the conductor and 250.64 covers its installation/routing — none of those address the approved connector types.

Correct: D — Metal underground gas piping

250.52(B)(1) specifically bans metal underground gas piping systems as a grounding electrode. Water pipes, concrete-encased electrodes, and ground rings are all electrodes addressed elsewhere in 250.52 as permitted types, not banned ones.

Correct: A — 250.190(C)(3)

250.190(C)(3) directs sizing of equipment grounding conductors per Table 250.122 based on the fuse rating or protective relay overcurrent setting. 250.190(C)(1) only sets the minimum conductor size/material when the EGC isn't part of a cable assembly, not the sizing method tied to OCPD rating.

Correct: A — The metal parts are isolated from ground so no person in contact with ground can contact them while energized

250.190(A) states the isolation exception exactly: metal parts don't need grounding if positioned so a person in contact with ground can't also contact them while the equipment is energized. A wood support, low voltage within the over-1000V class, or being outdoors and weatherproofed don't create this exception on their own.

Correct: C — Wire-type bonding jumpers at each corner and at intervals not exceeding 160 ft

250.194(A) applies to any metal fence within 5 m (16 ft) of exposed conductors or equipment — 12 ft qualifies. The rule requires bonding jumpers at each corner and at maximum 50 m (160 ft) intervals; there's no exception based on distance beyond 16 ft, a single jumper, or fence material. Section 250.194(A).

Correct: D — 250.68(A)

250.68(A) is the accessibility requirement for mechanical connections of the GEC/bonding jumper to the grounding electrode. 250.66(A) only addresses sizing the GEC for rod/pipe/plate electrodes, not whether the termination must be accessible.

Correct: B — Equipment grounding conductors, service-equipment enclosures, and the grounded service conductor (if the system is grounded)

250.24(E) requires the grounding electrode conductor to connect the equipment grounding conductors, the service-equipment enclosures, and, if the system is grounded, the grounded service conductor to the grounding electrode(s). The other options substitute different components (bonding jumper, feeders, raceways) that aren't the three items this section names.

Correct: A — 250.64(E)(1)

250.64(E)(1) is the general rule requiring ferrous raceways, enclosures, and cable armor for a GEC to be electrically continuous and bonded at both ends to the electrode or GEC. 250.64(B)(2) only addresses protecting the GEC itself from physical damage, not bonding the ferrous raceway around it.

Correct: A — Sized for the largest GEC required among all the electrodes it connects to

250.64(F) requires the grounding electrode conductor to be sized for the largest GEC required among all connected electrodes, not the smallest, an average, or a spliced mix of sizes.

Correct: B — The size of the largest ungrounded service-entrance conductor

250.66 directs that Table 250.66 is entered using the size of the largest ungrounded service-entrance conductor. Disconnect ampere rating, neutral size alone, and calculated load are not the table's lookup value.

Correct: C — Both electrodes must be bonded together to form the grounding electrode system

Per 250.50, all grounding electrodes described in 250.52(A)(1) through (A)(7) that are present at the building must be bonded together to form the grounding electrode system. Neither electrode is optional or preferred over the other, and no supplemental rod is required just because two electrodes already exist.

Correct: B — It must be listed as grounding and bonding equipment

250.94(A)(5) requires the IBT be listed as grounding and bonding equipment. It must be external to the enclosure (not inside it), must fit at least three conductors (not two), and if connected via a separate conductor to the grounding electrode conductor enclosure, that conductor must be a minimum 6 AWG copper, not 10 AWG.

Correct: A — It must terminate within the same building or structure directly at the EGC terminal of the applicable derived system or service

250.146(D) requires the isolated conductor to run with the circuit conductors and terminate directly at an EGC terminal of the applicable derived system or service within the same building or structure — it is not bonded to any panelboard bar it passes through, and it does not simply land on a grounding electrode.

Correct: A — Normally non-current-carrying metal parts of equipment

250.24(B) prohibits connecting the grounded conductor to normally non-current-carrying metal parts of equipment, equipment grounding conductors, or ground on the load side of the service disconnect. The main bonding jumper connection and grounding electrode conductor connection at the service are the permitted point where this bond is made, not a load-side violation.

Correct: A — It must be unspliced

250.24(C) specifically requires an unspliced main bonding jumper. It doesn't require external routing or oversizing beyond the standard sizing rules referenced in 250.28, and insulation/marking requirements aren't part of this section.

Correct: D — The case must not be connected to the equipment grounding conductor, and insulating mats are required above 150 volts to ground

250.174(C) specifically prohibits connecting cases to the equipment grounding conductor on live-front switchboards, and requires insulating rubber mats or other approved floor insulation where voltage to ground exceeds 150 volts. Grounding the case here (the first option) is the rule for dead-front equipment under 250.174(B), not live-front equipment — a common confusion point.

Correct: D — 400 m (1300 ft)

250.184(C)(4) caps the distance between any two adjacent electrodes at 400 m (1300 ft), the same interval required in 250.184(C)(3) for placing at least one electrode along the run. The other distances don't match the rule, and a maximum is explicitly stated, not just a minimum.

Correct: A — Any accessible point on the grounding electrode system

250.130(C)(1) permits connecting to any accessible point on the grounding electrode system as described in 250.50. A standalone rod not bonded into that system, an unbonded subpanel neutral bus, and water pipe past the 5 ft limit are not on the approved list.

Correct: B — That the requirements of 250.4(A)(5) or (B)(4) continue to be met

250.6(B) permits altering grounding/bonding connections to stop objectionable current only if the requirements of 250.4(A)(5) or (B)(4) are met, since those sections establish what makes grounding effective in the first place. The isolator device in 250.6(E) is a separate provision for cathodic protection systems, not a prerequisite for general alterations, and the other choices aren't conditions found in this section.

Correct: C — 250.86

250.86 covers metal enclosures and raceways for other-than-service conductors, including the specific exception for short additions to existing open wire, knob-and-tube, or nonmetallic-sheathed cable installations. 250.80 only addresses service raceways and enclosures, and 250.96 covers bonding of other enclosures generally, not this feeder/branch-circuit exception list.

Correct: B — A supply-side bonding jumper between the generator equipment grounding terminal and the equipment grounding terminal, bar, or bus of the disconnecting means

Per 250.35(B), a nonseparately derived generator without integral overcurrent protection requires a supply-side bonding jumper between the generator's equipment grounding terminal and the disconnect's equipment grounding terminal, bar, or bus, sized per 250.102(C). The 250.30 requirements apply only to separately derived systems under 250.35(A), not this case. An effective ground-fault current path is always required, so 'no grounding conductor' is wrong.

Correct: B — Automatically de-energize any component that develops a ground fault, and de-energize on loss of equipment grounding conductor continuity

250.188(D) requires automatic de-energization on a ground fault and continuous monitoring of the equipment grounding conductor's continuity, with automatic de-energization if that continuity is lost. Manual alarms, logging without interruption, and load-reduction schemes don't meet the automatic-shutdown requirement.

Correct: A — 250.30(C)

250.30(C) specifically addresses separately derived systems whose source sits outside the building, requiring a grounding electrode connection at that source location. 250.30(A)(4) covers the grounding electrode requirement for grounded separately derived systems generally (not the outdoor-source rule), and 250.32(A) applies to buildings supplied by a feeder from another building, not to the separately derived source's own outdoor location.