electrical systems
Which of the following is not a common service amperage? A) 400 B) 175A C) 100A D) 60A
The answer is 175A. A 175 amp service is not common.
The power available in a typical 15A, 120V household circuit is
The answer is 1800W. P = VI, P = 120 × 15 = 1,800 watts.
Plastic sheathing on branch wiring became popular in the
The answer is 1970s. Plastic sheathing on branch wiring became popular in the 1970's.
Assuming copper, standard wire type, and normal temperature rating, what is the typical conductor size (in awg) for a 200A service in the U.S.?
The answer is 2/0. A 200 amp service must have 2/0 gauge wire in the U.S.
You observe #6 gauge copper wires entering a service box with two 60A fuses inside. From the service box, #3 copper conductors lead to a newer combination panel that has a 100A main breaker. You should report the service size as
The answer is 60A. This is a 60-amp service, limited by the service entrance conductors and the main fuses. It doesn't matter what is downstream of that.
Aluminum wiring is still used on
The answer is 8 GAUGE CIRCUITS. Aluminum wiring is still used on #8 gauge circuits. Stranded aluminum wire is still common. That includes wires that are #8 gauge and larger.
Which of the following is a safety concern? A) A fuse that is too big B) A fuse that is too small
The answer is A FUSE THAT IS TOO BIG. A fuse that is too big is a safety concern.
A multi-wire circuit has a
The answer is A RED AND A BLACK WIRE. A multi-wire circuit has a red and black wire.
Twist-on connectors (wire nuts) are also called
The answer is ARE ALSO CALLED SOLDERLESS CONNECTORS. Wire nuts are also called solderless connectors.
Common copper wire sizes for an electric water heater are
The answer is #12, #10. Common wire sizes for water heaters are #12 and #10 gauge.
Assuming copper, standard wire type, and normal temperature rating, what is the typical conductor size (in awg) for a 60A service in the U.S.?
The answer is #6. #6 gauge wire is adequate for 60 amp service.
In general, modern 120V circuits can accommodate how many outlets and/or light fixtures?
The answer is 12. Roughly 12 outlets and/or light fixtures are permitted per circuit.
A service box with a black wire, a red wire, a white wire, and two 200A fuses indicates a
The answer is 120/240V, 200A SERVICE. A black, red, and white wire and 200 amp fuses indicate a 120/240 volt, 200 amp service.
The standard house voltage is
The answer is 120/240V. The standard house voltage is 120/240 volts.
What is a type P fuse? A) A "power" fuse, for 30A or more loads B) A gfci fuse C) A heat sensitive fuse D) A time-delay fuse
The answer is A HEAT SENSITIVE FUSE. A type P fuse is a heat sensitive fuse.
Four service entrance conductors indicates
The answer is A THREE-PHASE SERVICE. Four service entrance conductors indicate a three-phase service, which is beyond our scope.
GFI receptacles are
The answer is ARE ACCEPTED AS AN ALTERNATIVE FOR GROUNDING UNDER SOME CIRCUMSTANCES. GFI receptacles are accepted as an alternative for grounding under most retrofit circumstances.
Panels used with aluminum wire should be rated?
The answer is BE RATED CUAL. Panels used with aluminum wires should be rated CUAL.
An over-current protection device can be a
The answer is CAN BE A FUSE OR BREAKER. An over-current protection device is a fuse or breaker.
A 60A service can be
The answer is CAN BE ADEQUATE IN SOME CASES. A 60 amp service can be adequate in some cases.
You notice a wooden post as the support for the service drop. You should check for
The answer is CHECK FOR ROT, DAMAGE, OR MOVEMENT. When you see a wooden post supporting the service drop, you should check for rot, damage, or movement.
All of the following are common lighting problems except A) heat lamps over doors. B) lights with pull chains with no isolating links. C) closet lighting located on the wall above the door. D) conventional lights used in wet areas.
The answer is CLOSET LIGHTING LOCATED ON THE WALL ABOVE THE DOOR. Closet lighting located on the wall or ceiling above the door is acceptable.
The service drop wires connect to
The answer is CONNECT TO THE HOUSE AT THE DRIP LOOP. Service drop wires join the house at the drip loop.
After entering the service box, the neutral service entrance conductor should
The answer is CONNECT TO THE TERMINAL WITH THE GROUNDING ELECTRODE CONDUCTOR AND THE SERVICE NEUTRAL. The neutral service entrance conductor should connect to the terminal with the grounding conductor and the service neutral.
Common switch problems include all of the following except A) switches for garbage disposals on the front of base cabinets. B) damaged switches. C) dimmer switches with a positive shut off. D) inoperative switches.
The answer is DIMMER SWITCHES WITH A POSITIVE SHUT OFF. Dimmer switches with a positive shut off are not a problem.
Service entrance (se) cable must be securely clamped to the house
The answer is EVERY 30 INCHES, GENERALLY. Service entrance cables should be clamped to the house every 30 inches typically
These are all problems with fuses except A) fuses loose. B) no links on multi-wire circuit fuses. C) fuse holder broken. D) fuse manufacturer and panel manufacturer different.
The answer is FUSE MANUFACTURER AND PANEL MANUFACTURER DIFFERENT. It is not a problem if the fuse manufacturer is different from the panel manufacturer.
Which of the following is not an approved grounding method? A) Metallic underground water piping B) Ground rods C) Gas piping D) Metal frame of a building
The answer is GAS PIPING. Gas piping is not an approved grounding method.
White wires can sometimes act as black wires in
The answer is IN 240 VOLT CIRCUITS. White wires can sometimes act as black wires in 240 volt circuits.
Light fixtures are needed in all the following locations except A) stairwells with more than six treads. B) on the outside of the home near every exterior door. C) in clothes closets. D) each room.
The answer is IN CLOTHES CLOSETS. Light fixtures are not required in clothes closets.
Question ID: 386435 Overhead service wires A) must be at least 10 feet above a driveway. B) in most areas, must be 3 feet away from windows. C) cannot be run over decks under any circumstances. D) must clear a flat roof by 3 feet or more, in most areas.
The answer is IN MOST AREAS, MUST BE 3 FEET AWAY FROM WINDOWS. Overhead service wires must be 3 feet away from windows.
Overfusing is
The answer is INSTALLING A FUSE OR BREAKER THAT IS RATED TOO BIG FOR THE CONDUCTOR. Overfusing refers to installing a fuse or breaker that is too big for the conductor.
The grounded service conductor is caled
The answer is IS CALLED THE NEUTRAL. The grounded service conductor is the neutral.
Special grease on aluminum wires is found on
The answer is IS FOUND ON STRANDED WIRES. The special grease on aluminum wires is typically used on stranded wires.
Overloading the neutral wire on a multi-wire branch circuit
The answer is IS LIKELY IF THE BLACK AND RED WIRES ARE POWERED FROM THE SAME BUS. Overloading the neutral wire on a multi-wire branch circuit is likely if the black and red wires are powered from the same bus.
Knob-and-tube wire buried in insulation is
The answer is IS NOT PERMITTED IN SOME JURISDICTIONS IF THE INSULATION IS COMBUSTIBLE. Knob-and-tube wiring buried in insulation is not permitted in some jurisdictions if the insulation is combustible.
Disadvantages of pigtailing aluminum to copper wire are
The answer is IT ADDS MORE CONNECTIONS AND LEADS TO OVERCROWDING BOXES. Pigtailed connections with aluminum wire add more connections to the box and may lead to overcrowding.
Problems with aluminum wiring include all of the following except A) aluminum is softer than copper and easier to damage. B) the aluminum oxide is not a good conductor of electricity. C) it lacked a ground wire. D) it tends to creep.
The answer is IT LACKED A GROUND WIRE. Lacking a ground wire is not a common problem with aluminum wire.
During an inspection you find 20 blown 15-amp fuses beside the panel. You might tell your client
The answer is IT'S LIKELY THAT THERE IS AT LEAST ONE OVERLOADED CIRCUIT IN THE PANEL. All of these blown fuses tell you that there is at least one overloaded circuit that continually blows fuses.
What is linking?
The answer is LINKING ENSURES THAT TWO FUSES OR CIRCUIT BREAKERS ARE DISCONNECTED AT THE SAME TIME. Linking ensures that two fuses or circuit breakers are disconnected at the same time. This is important on 240-volt circuits or multi-wire branch circuits.
To check the connections of the wires inside the service box, you should
The answer is LOOK FOR MELTING, CHARRING, OR DAMAGE TO THE WIRE AND INSULATION. You should be looking for melting, charring, or damage to the wire and insulation.
Putting the fuses upstream of the disconnect switch in the service box
The answer is MAKES IT DANGEROUS TO CHANGE THE FUSES EVEN WHEN THE HOUSE POWER IS SHUT OFF. Putting fuses upstream of the disconnected switch in the service box makes it more dangerous to change the fuses. Even when the house power is shut off, there will be power to the fuse terminals.
Which statement is correct? A) Neutral and ground wires should be connected at the main panel and separate at subpanels. B) Neutral and ground wires should be connected at subpanels and separate at the main panel. C) Ground and neutral wires should always be connected. D) Hot and neutral wires should always be the same color.
The answer is NEUTRAL AND GROUND WIRES SHOULD BE CONNECTED AT THE MAIN PANEL AND SEPARATE AT SUBPANELS. Neutral and ground wires should be connected at the main panel and separated at sub panels.
All of these are common branch circuit problems except A) undersized wire. B) damaged wires. C) open splices. D) NMD wires run through floor joists without tubes or grommets.
The answer is NMD WIRES RUN THROUGH FLOOR JOISTS WITHOUT TUBES OR GROMMETS. NMD wires run through floor joists without tubes or grommets are not a problem.
All of the following are common outdoor wiring problems except A) NMW wiring used outdoors. B) wires running through downspouts. C) unprotected wires within four feet of the garage floor. D) garage door openers powered with an extension cord.
The answer is NMW WIRING USED OUTDOORS. NMW wire used outdoors is not a problem.
Is it permissible to use an aluminum grounding wire?
The answer is ONLY IN DRY ENVIRONMENTS IN THE UNITED STATES. Aluminum grounding conductors can only be used in dry environments in the United States.
Is the service drop overhead or underground? A) Overhead B) Underground
The answer is OVERHEAD. The service drop is the collection of overhead wires coming from the utility pole to the point of connection to the house.
Knob-and-tube wiring issues include all of the following except A) wires buried in insulation. B) overheated neutrals on multi-wire branch circuits. C) connections to modern wire not in boxes. D) brittle wire, insulation, or sheathing.
The answer is OVERHEATED NEUTRALS ON MULTI-WIRE BRANCH CIRCUITS. Overheated neutrals on multi-wire branch circuits are not specific to knob and tube wiring. Multi-wire branch circuits are, in fact, very rare on knob and tube wiring.
Three slot receptacles on ungrounded circuits are safety hazards because
The answer is PEOPLE WILL USE GROUNDED APPLIANCES, THINKING THE RECEPTACLE IS GROUNDED. Ungrounded three slot receptacles are a problem because people might use grounded appliances and expect that the receptacle is grounded.
All of these are functions of grounding systems except A) protects homeowners. B) dissipates static charges. C) provides an emergency path for electricity to escape. D) prevents short circuits.
The answer is PREVENTS SHORT CIRCUITS. Grounding does not prevent short circuits.
Cables within six feet of an access attic hatch should be
The answer is PROTECTED FROM MECHANICAL DAMAGE. Cables within six feet of an access attic hatch should be protected from mechanical damage.
subpanel is supplying a 3-ton air conditioner (running load amps = 18A) and an electric dryer (5000W). The 10 gauge copper subpanel feed wire is connected to a 60A breaker in the main panel. You should
The answer is RECOMMEND CHANGING THE SIZE OF THE FEED WIRE TO MATCH THE BREAKER. The breaker size and the feed wire size should be a match. Alternatively, the wire ampacity should be greater than the breaker rating. The ten gauge copper wire can safely carry 30 amps.
The main service fuses have been installed with the labels facing backward, not allowing you to read their rating. No other markings are visible. You should
The answer is REPORT THAT THE MAIN SERVICE FUSE RATING WAS NOT DETERMINABLE. You should report that the main service fuse rating was not determinable if you can't read the fuse labels.
You notice that the service drop and service entrance conductors are bare at the splice. You should do which of the following? A) None of these B) Report this as a safety hazard. C) Consider this acceptable if the conductors are secure. D) Wrap them in tape, if you carry any.
The answer is REPORT THIS AS A SAFETY HAZARD. Bare wires at the splice between the service drop and service entrance is a safety hazard.
A panel is servicing an indoor pool area, and is in a mechanical room next to the pool. You should be looking for
The answer is RUST PROBLEMS. Indoor swimming pool enclosures can be corrosive because of the chemicals. Watch for more than the usual amount of rusting.
Common branch circuit wire materials include all of these except A) Silver-dipped copper B) Aluminum C) Solder-dipped copper D) Copper
The answer is SILVER-DIPPED COPPER. Silver-dipped copper wires are not made, as far as we know.
How far should wires be kept from the metal vent connector on a gas appliance?
The answer is SIX INCHES. Wires should be kept six inches away from metal vent connectors on a gas appliance.
Which of the following is a suitable location for a branch circuit wire? A) Within one inch of the face of a stud B) Stapled to 2×4 studs C) Under carpets D) Attached to a baseboard with suitable staples every four feet
The answer is STAPLED TO 2×4 STUDS. Branch circuit wires can be stapled to 2×4 studs.
Extension cords are ____________ wire
The answer is STRANDED WIRE. Extension cords typically are stranded wire so that they will be more flexible than solid wire.
NMD cable is
The answer is SUITABLE FOR INDOOR USE. NMD cable is suitable for dry indoor use.
At the drip loop you notice that the service drop conductors are smaller in diameter than the service entrance conductors. You should conclude
The answer is THAT THIS IS A NORMAL SITUATION, AND IS ACCEPTABLE. The service drop conductors can be smaller than the service entrance conductors because the service drop conductors are in free air, whereas the service entrance conductors are in cable or conduit.
Putting a penny in a fuse holder is dangerous because
The answer is THE CIRCUIT HAS NO OVER-CURRENT PROTECTION. Putting a penny in a fuse holder means that the circuit has no over-current protection.
All of these are common closet lighting problems except A) the light is above a shelf. B) the light is mounted on a wall above the door. C) bare bulbs are used. D) installing the light above and toward one end of the shelf.
The answer is THE LIGHT IS MOUNTED ON A WALL ABOVE THE DOOR. Mounting the light on a wall above the door in a closet is not a problem.
Which of the following is a safety issue? A) The main fuses have a higher rating than the service entrance wire. B) The main fuses have a lower rating than the service entrance wire. C) The service box has a higher rating than the service entrance wire. D) The distribution panel has a larger rating than the service entrance wire
The answer is THE MAIN FUSES HAVE A HIGHER RATING THAN THE SERVICE ENTRANCE WIRE. If the main fuses have a higher rating than the service entrance wire, they will not shut off the electricity when the current levels become dangerous. Fire and electrical shock are possible in this situation.
What happens if the neutral wire bypasses the service box?
The answer is THE NEUTRAL AND GROUNDING SYSTEM WILL NOT BE PROPERLY CONNECTED. If the neutral wire bypasses the service box, the neutral and grounding system will not be properly connected to each other.
The term service drop defines
The answer is THE OVERHEAD WIRES COMING FROM THE UTILITY POLE TO THE POINT OF CONNECTION TO THE HOUSE. The service drop refers to the overhead wires coming from the utility pole to the house.
When replacing the panel cover, it's hard to get it back on without pinching or compressing the wires inside the box. You should conclude which of the following? A) The panel cover is too small for the panel. B) The panel is overcrowded. C) The wires are probably larger than necessary. D) None of these.
The answer is THE PANEL IS OVERCROWDED. The panel is overcrowded if you can't get the cover back on without pinching wires.
All of the following are common receptacle problems except A) the bathroom outlets are too far from basins. B) receptacles worn. C) the receptacle is too close to the basin. D) a pin is broken in the receptacle.
The answer is THE RECEPTACLE IS TOO CLOSE TO THE BASIN. Electrical authorities like receptacles in bathrooms to be close to the basin, although they shouldn't be right over the basin since the appliance cord may droop into the water.
The size of the fuse should be the same as
The answer is THE SAME AS THE RATING OF THE WIRE. Ideally, the size of the fuse should be the same as the rating of the wire. It should never be larger than the rating of the wire, since this is unsafe.
A house has service entrance conductors designed for 100 amps and a main disconnect rated at 100 amps. Which of these conditions is unsafe? A) The service box is rated at 75 amps. B) The distribution panel is rated at 200 amps. C) The service box is rated at 125 amps. D) The distribution panel is rated at 125 amps.
The answer is THE SERVICE BOX IS RATED AT 75 AMPS. A service box rated at 75 amps is not adequate for 100 amp service.
Which of the following is a reliable way to identify the service size? A) The service entrance conduit size B) The service entrance conductor size C) The distribution panel rating D) The size of the service drop wires
The answer is THE SERVICE ENTRANCE CONDUCTOR SIZE. The best indication of service size is the service entrance wires.
Grounded and grounding conductors must be connected at
The answer is THE SERVICE PANEL ONLY. Grounded and grounding conductors must be connected at the service panel only.
Which one of the following is a reliable indicator of service amperage? A) The size of the service drop wires B) The rating of the distribution panel C) The rating of the meter D) The size of the service entrance conductors
The answer is THE SIZE OF THE SERVICE ENTRANCE CONDUCTORS. The size of the service entrance conductors is the most reliable indicator of service amperage.
Double tapping is
The answer is THE TERM FOR ATTACHING TWO WIRES TO A SINGLE FUSE OR BREAKER TERMINAL. Double tapping is a term for attaching two wires to a single fuse or breaker. It is poor practice and not allowed in most cases.
As a general rule, how much clear space should be in front of the service box?
The answer is THREE FEET. There should be three feet of clear space in front of a service box.
Are service laterals overhead or underground?
The answer is UNDERGROUND. Underground services from the utility to the house are referred to as service laterals.
You plug your circuit tester into an outlet that has a washing machine plugged in. Your tester shows the outlet is properly wired and grounded. How could you improve this inspection process?
The answer is UNPLUG THE WASHING MACHINE. Unplugging the washing machine will ensure that your tester doesn't read a false ground connection through the washing machine.
Ohm's Law, the relationship between voltage, current, and resistance in a simple circuit, states
The answer is V=IR. V = IR and R= V/I.
The unit for the measure of electrical power is
The answer is WATTS. The unit for the measure of electrical power is watts.
The main fuses or breakers are most likely to trip:
The answer is WHEN MANY LARGE APPLIANCES ARE ON. The main fuses or breakers are most likely to trip when many large appliances are used simultaneously.
Common junction box problems include all of the following except A) wire nuts inside boxes. B) overcrowded boxes. C) missing boxes. D) boxes missing cover plates.
The answer is WIRE NUTS INSIDE BOXES. Wire nuts should be found inside boxes.
Supports for branch circuit wires are needed
The answer is WITHIN 12 INCHES OF LEAVING A BOX. Branch circuit wires should be supported within 12 inches of leaving a box.
With respect to amperage ratings, the main fuses or breaker
The answer is should be sized to adequately protect the service entrance wires and should be no larger than the rating of the service box. The main fuses or breakers should be sized to adequately protect the service entrance wires and should be no bigger than the rating of the service box.
If you can't read the size of the fuses in the service box, you should remove them to try to get a better look. True False
The statement is FALSE. Do not touch anything in the service box. The fuses may be live and could kill you.
Electrical wiring in a house is direct current. True False
The statement is FALSE. Electrical wiring in a house is alternating current.
The drip loop should be as close to the roof surface as possible. True False
The statement is FALSE. The bottom of the drip loop should be well above the roof—12 to 24 inches, depending on jurisdiction.
The drip loop is typically part of the service drop. True False
The statement is FALSE. The drip loop is part of the service entrance wires, not the service drop
All service entrance conductors must be in conduit. True False
The statement is FALSE. The service entrance wires may be in a conduit on the outside of the building or there may be a special Service Entrance (SE) cable that does not require a conduit.
There can be up to ten throws to disconnect all of the electricity in the house. True False
The statement is FALSE. There can be up to six throws to disconnect all of the electricity in the house.
Larger appliances usually have 240 volts. True False
The statement is TRUE. 240-volt circuits are used for large appliances such as stoves, electric water heaters, electric clothes dryers, air conditioners, and saunas
Aluminum is an acceptable service entrance conductor material. True False
The statement is TRUE. Service entrance conductors may be aluminum or copper.
Service entrance conductors run from the service drop to the service box or service panel. True False
The statement is TRUE. Service entrance conductors pick up where the service drop wires end and extend down to the service panel.
The size of the electrical service has to be reported according to ASHI™ Standards. True False
The statement is TRUE. The Standards ask us to report the service size (amperage and voltage rating).
The service size is determined by the amperage and voltage ratings of the service. True False
The statement is TRUE. The size of the electrical service is a function of both the voltage and amperage.