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Grounding & Bonding — Electrician Practice Questions

64 questions · 14% of the Electrician exam

Worked questions

1. Which description matches a concrete-encased electrode that qualifies for use in the grounding electrode system?

  • At least 20 feet of bare copper conductor no smaller than 4 AWG, encased in at least 2 inches of concrete near the bottom of a footing that is in direct contact with the earth.
  • BAt least 10 feet of insulated copper conductor laid into the floor slab directly above the vapor barrier and carried to the service enclosure.

    Both the length and the location fail. A vapor barrier isolates the concrete from the soil, which removes the earth contact the electrode depends on, and 10 feet is half the length the section requires.

  • CAt least 20 feet of bare copper conductor no smaller than 8 AWG laid on top of the finished footing before the foundation walls are formed and poured.

    The conductor is two sizes too small and it is not encased in anything. Lying on a cured footing provides none of the 2 inches of concrete cover the definition calls for, so the error path gets the length right and misses the rest.

  • DAny length of reinforcing steel tied together in the foundation, provided each bar carries a nonconductive epoxy coating that protects it from corrosion for the life of the building.

    A nonconductive coating stops the steel from making electrical contact with the concrete around it, so epoxy-coated bar cannot serve as the electrode. The Code also states a minimum bar size and a minimum length rather than accepting any amount.

Why A is correct

It hits every element: minimum length, minimum conductor size, bare conductor, minimum concrete cover, and a footing in direct earth contact. Miss any one of those and the electrode does not qualify. Reinforcing steel of the stated diameter may be substituted for the copper conductor.

What this question is testing

Whether you can recognize a qualifying concrete-encased electrode from a physical description and spot the details that disqualify it, particularly loss of direct earth contact, an undersized conductor, and coatings that break the electrical path between steel and concrete. Jobsite timing is part of the same knowledge.

On the job

This electrode is usually the best performer on the site because a footing presents an enormous surface to the soil. Coordinate with the concrete sub before the pour: either clamp a listed connector to the bottom rebar mat and stub a conductor up out of the form, or lay twenty feet of bare 4 AWG in the footing and bring the tail up. Rebar sections may be tied together in the usual way to reach the 20 feet. After the pour it is gone.

Memory technique

Twenty feet in the footing, two inches of cover, no plastic underneath.

Exam tip

For this electrode, memorize twenty feet, 4 AWG bare copper or half-inch rebar, two inches of concrete, footing on dirt.

Where to look it up

It is one of the numbered electrode types in the electrode list of Article 250 Part III.

2. On a 20-ampere branch circuit the ungrounded copper conductors are increased from 12 AWG to 8 AWG to correct voltage drop. What minimum size copper equipment grounding conductor is now required for that circuit?

  • A12 AWG copper

    12 AWG is the unadjusted table value. Forgetting the proportional increase entirely is the most common mistake, and it leaves the fault path with higher impedance than the circuit was designed for.

  • B10 AWG copper

    10 AWG reflects only a one-size increase. The proportional calculation lands above 10 AWG at 10,380 circular mils, so this conductor is still too small.

  • C6 AWG copper

    6 AWG at 26,240 circular mils is well beyond what the ratio requires. Increasing by more than the proportion wastes copper and can make terminations difficult.

  • 8 AWG copper

Why D is correct

When ungrounded conductors are increased above the minimum size needed for ampacity, any wire-type equipment grounding conductor must be increased proportionally by circular mil area. Two AWG sizes up on the phase conductors works out to two AWG sizes up on the ground.

What this question is testing

Whether you can carry out a proportional circular mil calculation, and whether you know that enlarging conductors for voltage drop triggers a matching increase in the equipment grounding conductor. It also checks that you can look up circular mil areas rather than estimating the proportion by eye.

On the job

Long runs to outbuildings, pole lights and well pumps routinely get upsized for voltage drop, and the ground gets forgotten because nobody thinks of it as a current-carrying conductor. The reasoning is sound though: if you lowered the impedance of the supply conductors, the fault path should keep pace so the breaker still sees enough current to trip. Note the increase applies only when conductors are enlarged above the size that would have had sufficient ampacity.

Memory technique

Upsize the hots, upsize the ground by the same number of steps.

Exam tip

A shortcut that works with standard AWG steps: move the ground up the same number of sizes you moved the phase conductors.

Where to look it up

The proportional increase rule sits in the equipment grounding conductor sizing section just after the general rule. Circular mil areas are in the conductor properties table in Chapter 9.

3. Why does the Code require the effective ground-fault current path to be a low-impedance metallic path rather than a connection to the earth?

  • Because enough current must flow to open the overcurrent device quickly, and the resistance of soil is far too high to allow that amount of current.
  • BBecause connections to earth corrode over time and gradually lose the ability to carry fault current back to the transformer that supplies the building.

    Corrosion is a real maintenance concern for buried connections, but it is not why the earth is unsuitable. Even a brand-new, perfectly made earth connection has far too much impedance to clear a fault.

  • CBecause the earth conducts current in only one direction and therefore cannot serve as a return path for an alternating current fault.

    The earth conducts alternating current in both directions like any other conductive medium. The limitation is resistance, not directionality, and a rod passes only a few amperes at 120 volts.

  • DBecause a metallic path is what keeps the voltage on the grounded conductor from rising above the voltage of the utility neutral at the pole.

    Stabilizing voltage with respect to earth is a purpose of the grounding electrode system, not the reason the ground-fault current path must be metallic and low impedance.

Why A is correct

Overcurrent devices are current-operated. A path with high impedance limits fault current to a value below the trip threshold, so the faulted metal stays energized indefinitely. Only a low-impedance metallic path back to the source produces a fast trip. A path through soil simply cannot deliver that much current at utilization voltage.

What this question is testing

Whether you understand the physical reason behind the entire equipment grounding scheme, which is the concept that unifies bonding jumpers, equipment grounding conductors and the prohibition on using earth as a fault path. It also checks that you can reject any answer routing fault current back to the source through the soil, which is the single most reliable filter on grounding questions.

On the job

Run the arithmetic once and it sticks: a 120-volt circuit faulted to a metal box that is connected only through 25 ohms of earth passes under 5 amperes. The breaker never moves, the box stays hot, and the first person who touches it becomes part of the circuit. That is why a detached building still needs an equipment grounding conductor run with the feeder even though it has its own rod, and why a bootleg ground on a metal water pipe is not an acceptable substitute.

Memory technique

Dirt does not trip breakers.

Exam tip

Any answer that has fault current returning through the soil is wrong.

Where to look it up

The performance requirements for the effective ground-fault current path are in the general section at the front of Article 250, and the term is defined in Article 100.

4. A building is served by 500 kcmil copper service conductors, which by the grounding electrode conductor table would ordinarily call for a 1/0 copper conductor. A ground ring of 2 AWG bare copper encircles the building, and the grounding electrode conductor being installed connects to nothing but that ring. What size is required for that conductor?

  • A1/0 AWG copper

    One-ought is what the table gives for 500 kcmil service conductors, and it would be correct for a conductor running to a water pipe or metal in-ground support structure. The ring cap overrides it for this particular run.

  • B6 AWG copper

    Six AWG is the cap that applies where the sole connection is to rod, pipe or plate electrodes. It is the right idea applied to the wrong electrode type.

  • C4 AWG copper

    Four AWG is the cap for a conductor whose sole connection is to a concrete-encased electrode. Again the concept is correct but it belongs to a different electrode.

  • 2 AWG copper

Why D is correct

The ring itself is 2 AWG bare copper, and the Code says the portion of the grounding electrode conductor whose sole connection is to a ground ring need not be larger than the ring conductor. Running 1/0 to a 2 AWG ring would put a large conductor in series with a small one, which buys nothing.

What this question is testing

Tests whether you know that the grounding electrode conductor table sets a maximum as well as a minimum, that the maximum depends on which electrode the conductor terminates on, and whether you can keep the three separate caps for rings, rods and concrete-encased electrodes straight from one another.

On the job

Ground rings are common on commercial and institutional buildings, communication sites and anywhere a designer wants a low, stable ground reference. The three separate caps trip people up because they all live in the same section and all sound alike. In the field the practical consequence is money: on a large service the difference between 1/0 and 2 AWG copper around a building perimeter is significant, and knowing the cap is what lets you bid it right.

Memory technique

You never need a conductor bigger than the electrode it lands on.

Exam tip

Sole connection to a rod caps at 6 AWG, to a concrete-encased electrode at 4 AWG, to a ground ring at the ring conductor size.

Where to look it up

Article 250, the grounding electrode conductor sizing section. The caps are written as separate subsections immediately following the reference to the table, not inside the table itself.

5. Interior metal gas piping in a commercial kitchen is likely to become energized because it serves appliances supplied by a 240-volt, 30-ampere branch circuit. On what basis does the Code establish the minimum size of the bonding jumper for that piping system?

  • From the equipment grounding conductor table, using the rating of the overcurrent device of the circuit likely to energize the piping
  • BFrom the grounding electrode conductor table, using the size of the ungrounded service-entrance conductors, the same basis used for water piping

    That table and that basis belong to the metal water piping system, which is bonded on the service conductor size because anything in the building can energize it. Gas piping is sized from the circuit likely to energize it.

  • CFrom the ampacity table, using the ampacity of the largest feeder in the building that could contact the piping

    Ampacity tables size conductors for continuous load current, not for fault duty. No bonding jumper anywhere in the Code is sized from the ampacity of a feeder, whichever feeder is picked.

  • DIt is fixed at 6 AWG copper for every metal piping system other than water piping, regardless of the circuit involved

    There is no fixed size, and the circuit is precisely what the rule turns on. The jumper scales with the overcurrent device of the circuit likely to energize the piping, so a 30-ampere circuit and a 400-ampere circuit give very different answers.

Why A is correct

Piping that becomes energized does so through a specific circuit, so the Code sizes its bonding jumper from that circuit's overcurrent device using the equipment grounding conductor table. The jumper only has to carry fault current from that circuit long enough to open its device, which is a very different job from bonding the water piping system.

What this question is testing

Tests whether you can distinguish the two piping bonding rules, one keyed to the service conductor size for water piping and one keyed to the branch-circuit overcurrent device for other piping, and whether you know that the circuit equipment grounding conductor may serve as the bonding means for the second case.

On the job

Gas piping bonding is one of the most argued items on a residential or restaurant final. The practical outcome is often that no separate jumper is needed at all, because the equipment grounding conductor running to the furnace, boiler or rooftop unit already satisfies the requirement. Corrugated stainless steel tubing systems are a different matter, since their manufacturers frequently require a direct bonding connection with its own minimum size stated in the installation instructions.

Memory technique

Water bonds to the whole house; gas bonds to the one circuit that can bite it.

Exam tip

Water piping looks at the service; every other piping system looks at the circuit that could energize it.

Where to look it up

Article 250, the bonding of piping systems and exposed structural metal section. The water piping subsection and the other piping subsection sit next to each other and point to different tables.

6. Which of the following is specifically not permitted to be used as a grounding electrode?

  • AA metal underground water pipe in direct contact with earth for 10 feet or more

    Underground metal water pipe with at least 10 feet of earth contact is the first electrode listed, subject to the requirement that it be supplemented by another electrode.

  • A metal underground gas piping system
  • CA concrete-encased 20-foot length of 1/2 inch steel reinforcing bar

    Twenty feet of half-inch reinforcing bar encased in concrete in contact with earth is the concrete-encased electrode, one of the most effective electrodes available.

  • DA ground ring of 20 feet of bare 2 AWG copper buried below the frost line

    A ground ring of at least 20 feet of bare copper not smaller than 2 AWG is a recognized electrode when installed at the required depth.

Why B is correct

The list of recognized electrodes is short, and the list of things specifically excluded is shorter still: underground metal gas piping and aluminum electrodes. Gas piping is excluded because deliberately routing fault or lightning current through a fuel line is unacceptable, and because gas systems commonly include insulating fittings that break the path anyway.

What this question is testing

The item tests whether the candidate knows the short list of excluded electrodes and can separate bonding a metal piping system from using it as an electrode.

On the job

Gas piping gets proposed as an electrode surprisingly often on rural and older jobs where nothing else is convenient, and the clamp is easy to install. It is a flat violation and a safety problem that a plumber replacing a section with a dielectric union can make worse without knowing. The correct move is a driven rod or a concrete-encased electrode, plus bonding the gas piping through the equipment grounding conductor of the circuit likely to energize it.

Memory technique

Bond the gas line. Never ground to it.

Exam tip

Two things are excluded outright as electrodes: underground gas piping and aluminum. Everything else is a question of meeting the conditions.

Where to look it up

Look in the grounding article at the section listing grounding electrodes, and read the subsection covering electrodes not permitted for grounding.

7. A service is supplied by two parallel sets of 250 kcmil copper conductors per phase. The bonding jumper sizing table assigns a 2 AWG jumper where the supply conductors are over 3/0 through 350 kcmil, and a 1/0 jumper where they are over 350 kcmil through 600 kcmil. What size copper supply-side bonding jumper is required for a service raceway?

  • A2 AWG copper

    Two AWG comes from reading the table with a single 250 kcmil conductor. That halves the basis and produces a jumper undersized for a paralleled service.

  • 1/0 AWG copper
  • C4 AWG copper

    Four AWG is smaller still and corresponds to service conductors of 2/0 or 3/0, far below the equivalent area here.

  • D3/0 AWG copper

    Three-aught is the largest size the table reaches and corresponds to service conductors well above 1,100 kcmil equivalent, so it is oversized for this service.

Why B is correct

The rule turns on equivalent area, not on the size of any one conductor. Two 250 kcmil conductors per phase equal 500 kcmil, and the table row covering over 350 through 600 kcmil calls for 1/0 AWG copper. The same principle governs the main bonding jumper and the grounding electrode conductor at a paralleled service.

What this question is testing

The item tests whether the candidate combines parallel conductors into an equivalent area before entering a sizing table, and can read the correct row from supplied table values.

On the job

Paralleled services are routine at 400 amperes and above, and the equivalent-area step is the one most often skipped. The consequence is a bonding jumper that cannot carry the available fault current long enough for the utility protection to clear, which is exactly the condition that turns a bolted fault into an arcing fault inside the gear. On the drawing, showing the equivalent area next to the jumper size makes the calculation reviewable.

Memory technique

Parallel means add the circular mils first, then look up once.

Exam tip

Whenever conductors are paralleled, add the circular mils per phase before you open any sizing table.

Where to look it up

Look in the grounding article at the section on bonding jumpers on the supply side of the service, and use the sizing table referenced there.

8. Under what condition does the Code require the exposed noncurrent-carrying metal parts of fixed equipment to be grounded because of where the equipment is located?

  • Where it is within 8 feet vertically or 5 feet horizontally of ground or grounded metal that persons can touch
  • BWhere it operates at more than 50 volts to ground, regardless of where in the building it is installed or how it is mounted

    Voltage to ground appears in the section, but the threshold is not 50 volts and voltage alone is not the location-based trigger this question asks about.

  • CWhere it is installed in a room whose floor is concrete rather than wood or another insulating material

    Floor material is a reasonable-sounding proxy for a grounded surface, but the Code states the rule in terms of distance from ground or grounded metal objects.

  • DWhere it weighs more than 100 pounds and is fastened permanently to the building structure or its steel

    Weight and permanence describe what makes equipment fixed rather than portable. They do not decide whether grounding is required.

Why A is correct

The zone is defined by human reach. Within 8 feet up or 5 feet across, a person standing on or touching grounded metal can also touch the equipment, so a fault that energizes the frame puts full voltage across that person. Grounding the frame gives the fault a path that opens the overcurrent device instead.

What this question is testing

The item tests recall of a dimensional criterion and whether the candidate can distinguish a location-based trigger from voltage-based and construction-based ones in the same section.

On the job

The 8-foot and 5-foot figures decide a lot of everyday questions: whether a metal-cased control panel in a shop needs a grounding conductor, whether a piece of process equipment sitting near structural steel is in the zone, and how far a metal enclosure has to be from a grounded pipe to fall outside it. In practice almost everything in an industrial building lands inside the zone, which is why grounding fixed equipment is close to universal.

Memory technique

Eight feet up, five feet across. Inside that box, ground it.

Exam tip

Grounding requirements for fixed equipment come in a list. Read the whole list before deciding a piece of equipment is exempt.

Where to look it up

Look in the grounding article at the section on equipment fastened in place or connected by permanent wiring methods.

56 more in the bank

Answers and explanations for these are in the app.

  • In the terminology the National Electrical Code uses, what does bonding accomplish that grounding does not?
  • A bare copper conductor leaves the service enclosure, passes through the sill plate, and terminates on a driven rod outside the building. What is this conductor properly called?
  • No equipment grounding conductor exists in the outlet box. What does the Code permit when a nongrounding receptacle is replaced with a grounding-type receptacle?
  • What does the main bonding jumper in service equipment actually connect, and why is that connection required?
  • How must the neutral bar and the equipment grounding bar be treated in a panelboard located on the load side of the service disconnecting means?
  • Steady current is measured on the equipment grounding conductor of a feeder under normal load conditions with no fault present. What is the most likely cause?
  • When more than one type of qualifying grounding electrode is present at a building or structure, how must those electrodes be handled?
  • A metal underground water pipe in direct contact with the earth is being used as a grounding electrode. What additional requirement applies to it?
  • A single rod electrode has been installed and its resistance to earth has never been measured. What does the Code require in that situation?
  • What are the minimum requirements for a ground ring used as a grounding electrode at a building?
  • What installation restriction applies when an aluminum grounding electrode conductor is used at a service?
  • The ungrounded service entrance conductors are 3/0 AWG copper, and the grounding electrode conductor will run from the service enclosure to the metal underground water pipe electrode. What is the minimum size copper grounding electrode conductor required?
  • The grounding electrode conductor runs from the service enclosure and its only termination is on the driven rod electrodes. What is the largest size copper conductor the Code requires for that run?
  • A circuit is protected by a 60-ampere overcurrent device ahead of the conductors. What is the minimum size copper equipment grounding conductor required for that circuit?
  • The feeder is protected by a 200-ampere overcurrent device and the ungrounded conductors are 4/0 AWG aluminum. What minimum size copper equipment grounding conductor must be pulled with that feeder?
  • Under what condition does the Code recognize a metal raceway itself as an equipment grounding conductor for the circuit inside it?
  • On what basis is the required size of the bonding jumper for the interior metal water piping system at a service determined?
  • A feeder supplies a detached building on the same premises. How must the equipment in that detached building be grounded under the current edition of the Code?
  • For a separately derived system such as a transformer secondary, where does the Code permit the system bonding jumper to be installed?
  • A service is arranged with three separate service disconnecting means in three separate enclosures fed from one set of service conductors at the meter. How does the Code permit the grounding electrode connection to be made for this arrangement?
  • The ungrounded service-entrance conductors at a service are 350 kcmil copper, one conductor per phase. The grounding electrode conductor table gives 8 AWG copper for service conductors 2 AWG and smaller, 6 AWG for 1 or 1/0, 4 AWG for 2/0 or 3/0, 2 AWG for over 3/0 through 350 kcmil, and 1/0 AWG for over 350 through 600 kcmil. What minimum copper main bonding jumper is required?
  • The secondary of a transformer forms a separately derived system whose derived ungrounded conductors are 3/0 AWG copper. The applicable table gives 8 AWG copper for conductors 2 AWG and smaller, 6 AWG for 1 or 1/0, 4 AWG for 2/0 or 3/0, and 2 AWG for over 3/0 through 350 kcmil. What minimum copper system bonding jumper is required?
  • A dry-type transformer creates a separately derived 208Y/120-volt system inside a building. Where must the grounding electrode conductor for that derived system be connected, and how is the location of that connection controlled?
  • A motor branch circuit uses copper circuit conductors of 10 AWG and is protected by a 100-ampere inverse-time circuit breaker, a rating permitted so the motor can start without tripping. The equipment grounding conductor table gives 8 AWG copper for a 100-ampere overcurrent device. What size copper equipment grounding conductor is required?
  • A commercial building has an exposed structural metal frame whose members are interconnected to form the building frame, but no part of that frame is in direct contact with the earth. What does the Code require regarding that structural metal?
  • A detached pump house on the same premises is supplied by a single 20-ampere branch circuit run underground from the dwelling, and that circuit includes an equipment grounding conductor. What does the Code require regarding a grounding electrode at the pump house?
  • A technician wants to disconnect the equipment grounding conductor from a sensitive electronic instrument because ground-path noise is corrupting its readings, and cites the Code rules on objectionable current as justification. How does the Code treat that proposal?
  • A 6 AWG copper grounding electrode conductor runs along the exterior surface of a building from the service enclosure to a driven rod, in a location that is not subject to physical damage. How may that conductor be installed?
  • The Code recognizes a metal in-ground support structure as one type of grounding electrode. Which description matches an installation that qualifies under that category?
  • An electrician plans to connect the grounding electrode conductor from a driven rod to the interior copper water piping about 40 feet inside the building, intending to use that piping as the path back toward the service. How does the Code treat that plan?
  • The system bonding jumper for a transformer-derived 208Y/120-volt system is installed at the first disconnecting means rather than at the transformer itself. What additional requirement applies to the conductors between the transformer and that disconnect?
  • Type AC cable and ordinary interlocked-armor Type MC cable are both run above a suspended ceiling in a commercial building. How does the Code treat the metal armor of each cable with respect to serving as the equipment grounding conductor for the circuits inside?
  • A permanently installed standby generator supplies a building through a transfer switch that opens and closes only the ungrounded conductors, while the grounded conductor passes through solidly connected. How must that generator be treated for grounding and bonding purposes?
  • A metal raceway run outdoors includes expansion fittings so the conduit can move with temperature changes, and the raceway itself is being relied on as the equipment grounding conductor. What does the Code require at each of those fittings?
  • A new service is being installed on a one-family dwelling, and the telephone, cable television and satellite antenna installers will each need to bond their systems to the electrical grounding system. What does the Code require the electrical contractor to provide for that purpose?
  • A service is supplied by four paralleled 400 kcmil copper conductors per phase, an equivalent area of 1,600 kcmil per phase. Where the service-entrance conductors exceed 1,100 kcmil copper, the main bonding jumper must have an area not less than 12.5 percent of the area of the largest phase conductor. Given that 3/0 AWG is 167,800 circular mils and 4/0 AWG is 211,600 circular mils, what is the minimum copper main bonding jumper?
  • An electrician installs the three ungrounded conductors and the grounded conductor of a feeder in one metal raceway, then pulls the wire-type equipment grounding conductor for that same feeder through a separate parallel raceway. How does the Code treat that arrangement?
  • A portable hand tool used on a construction site is listed and marked as double insulated and is supplied by a two-wire cord and attachment plug with no grounding pin. How does the Code treat the absence of an equipment grounding conductor connection for that tool?
  • At a large service, several grounding electrode conductors and bonding jumpers need a common termination point. What arrangement does the Code specifically permit for that purpose?
  • A meter enclosure is installed ahead of the service disconnecting means, on the supply side. How may that enclosure be grounded?
  • A service is supplied by 250 kcmil aluminum ungrounded conductors, one per phase. The sizing table lists, for aluminum service conductors, 1/0 and smaller in the first row, 2/0 or 3/0 in the second row, 4/0 or 250 kcmil in the third row, and over 250 through 500 kcmil in the fourth row. The corresponding copper electrode conductors for those rows are 8 AWG, 6 AWG, 4 AWG and 2 AWG. What copper grounding electrode conductor is required?
  • Two rod electrodes are being installed as part of the grounding electrode system at a service. What minimum separation does the Code require between them?
  • A ground rod being driven at a new service strikes solid rock about 4 feet down and will go no farther. What does the Code permit?
  • A plate electrode is being installed as part of the grounding electrode system. What does the Code require of it?
  • An equipment grounding conductor has to be terminated to a metal outlet box that was supplied with no grounding terminal in it. Which method of making that connection does the Code accept?
  • A building has a lightning protection system with its own down conductors and driven ground terminals. How must that system relate to the electrical grounding at the service?
  • In a residential occupancy, which cord-and-plug-connected appliance does the Code specifically require to have its exposed noncurrent-carrying metal parts grounded?
  • A separate equipment grounding conductor is being run to a replacement grounding-type receptacle in an older dwelling whose branch circuit contains no equipment grounding conductor. Where does the Code permit that conductor to be connected?
  • Circuit conductors are spliced in a box, and a receptacle is installed there as well. What does the Code require of the equipment grounding conductors associated with those circuits?
  • Which of these alternating-current systems operating between 50 and 1000 volts does the Code require to be grounded?
  • The main bonding jumper in a service panelboard takes the form of a screw. What does the Code require of that screw?
  • A service is supplied by four parallel sets of 500 kcmil copper conductors per phase. The sizing table calls for a 1/0 electrode conductor where the service conductors are over 350 through 600 kcmil, a 2/0 conductor for over 600 through 1,100 kcmil, and a 3/0 conductor for anything larger than 1,100 kcmil. What size copper grounding electrode conductor does the table require?
  • At a grounded service, where does the Code permit the grounding electrode conductor to be connected to the grounded service conductor?
  • A short piece of metal conduit is installed over a nonmetallic-sheathed cable purely to protect the cable from physical damage. Must that sleeve be connected to an equipment grounding conductor?
  • A dry-type transformer creates a separately derived 208Y/120-volt system serving one floor of a building. What does the Code require regarding the metal water piping in the area served by that system?
  • A grounding connection is being made to a metal enclosure whose contact surface is covered with paint. What does the Code require?

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