Electrical Systems Flashcards
I didn't modify this DECK, because you passed at 100%. (168 cards)
1
Q
Ampacity
A
the maximum current that a conductor or device may carry continuously without exceeding its temperature rating
AMPERES(AMPS)=current
Ohm’s Law symbol = I
2
Q
AWG
A
the abbreviation for American Wire Gauge, a system for identifying the diameter of electrical wires; larger numbers identify smaller diameter wires; #14 (pronounced number 14 or 14 gauge) is the smallest wire used in house wiring, and 4/0 (pronounced four-oh) is usually the largest.
3
Q
Bonding
A
the process of connecting, both physically and electrically, metal components of the electrical system that are not intended to carry electrical current to provide a low resistance return path to the circuit breaker or fuse to clear ground faults; bonding is an electrical safety system.
4
Q
Branch circuit
A
Conductors that begin at a circuit breaker or fuse and serve one or more outlets.
5
Q
Branch circuit, multiwire
A
a branch circuit in which two energized conductors share one neutral conductor; examples can include clothes dryers, ranges and other cooking appliances, and split-wire receptacle circuits; 240 volt water heaters and condensers for air conditioners and heat pumps are not usually multiwire branch circuits
6
Q
Bus (buss, busbar)
A
The heavy, rigid metal part of a panelboard on which circuit breakers or fuses are mounted; sometimes used to describe metal terminals to which the neutral(Grounded Conductor) and Equipment Grounding Conductors(EGC) are connected.
7
Q
Cable
A
two or more conductors encased in sheathing; examples include non-metallic sheathed cable (often referred to by the brand name Romex) and armored cable (often referred to by the brand name BX)
8
Q
Circuit breaker
A
A fuse or a circuit breaker; Overcurrent Protection Devices(OPD) interrupt the flow of electricity when a set current flow is exceeded (an overload), or when a short circuit fault is detected; these devices prevent conductors and devices from overheating and causing fires
9
Q
Conductor
A
a material, such as copper or aluminum, that permits electricity to flow with low resistance; wires are conductors
10
Q
Current
A
The amount of electricity in a circuit; (similar to water gallons per minute; water flow in a pipe); unit of measure is the Ampere (Amp); expressed as I in Ohm’s Law and Watt’s Law equation
11
Q
Dead front cover
A
a panel that is removed to gain access to the energized components inside an enclosure; the dead front cover is usually behind a door that must be swung or lifted to gain access to the dead front cover
12
Q
EGC
A
Equipment Grounding Conductor
A bare or green insulated conductor that provides a ground fault current path (a bonding connection) for equipment with metal cases and parts; these have been installed in most house branch circuit wiring since around 1960
13
Q
Enclosure (electrical)
A
a case or cabinet intended to prevent accidental contact with energized parts; a panelboard is housed inside an enclosure
14
Q
Feeder conductors
A
Conductors from the service equipment, or from a panelboard that supply electricity to another panelboard - such as a subpanel.
15
Q
Fuse
A
A fuse or a circuit breaker; Overcurrent Protection Devices(OPD) interrupt the flow of electricity when a set current flow is exceeded (an overload), or when a short circuit fault is detected; these devices prevent conductors and devices from overheating and causing fires.
16
Q
Grounded
A
A conductor that is intentionally connected to the earth; this describes what is often called the neutral conductor.
17
Q
Grounding
A
Providing an intentional connection to the earth; grounding provides an alternate path for current to return to its source; in an electrical power system, the source is the utility’s transformer and ultimately the power plant.
18
Q
Equipment Grounding Conductor
A
A bare or green insulated conductor that provides a ground fault current path (a bonding connection) for equipment with metal cases and parts. These have been installed in most house branch circuit wiring since around 1960.
19
Q
Grounding electrode
A
metal that is in direct contact with the earth and serves as the electrical system grounding connection; examples include copper-coated steel rods, galvanized steel pipes, water service and well pipes, and reinforcing steel encased in the footings.
20
Q
Grounding Electrode Conductor (GEC)
A
A conductor that runs between the grounding electrode and an accessible point downstream from where the grounded service entrance conductor connects to the service drop or lateral; the GEC connection is usually at the service equipment.
21
Q
Ground fault
A
An event that occurs when metal that should not conduct electricity (such as a metal water pipe) becomes energized; if the metal is properly bonded, current flow should increase in the circuit and trip the circuit breaker or fuse.
22
Q
Ground fault circuit interrupter (GFCI)
A
A circuit breaker or receptacle that detects a Ground Fault by monitoring the imbalance in Current flow between the energized(Ungrounded Conductor), and neutral conductors(Grounded Conductor) and stops Current flow (opens the circuit) when a Ground Fault is detected.
23
Q
Joules Law
A
A formula for calculating heat in an electrical circuit expressed as Heat = Current2 X Resistance X Time.
P=I²R
24
Q
Knockouts
A
stamped openings in an enclosure where conduit or cable clamps are installed to secure conductors or cables. See Tabs (twistouts).
25
Load Center
Panel (panelboard, load center): the equipment on which circuit breakers or fuses are mounted; panels include associated terminal bars; a panelboard is contained in an Enclosure; the first and usually the largest panel is often referred to as the main panel or the service panel; however, there are no generally accepted terms to identify panels
26
Lug
A connection point where conductors are inserted and secured; examples include the connection points on panelboards for service entrance and feeder conductors, on terminal bars for neutral(Grounded Conductors) and EGCs(Equipment Grounding Conductor), and on circuit breakers(Overcurrent Protection Device[OPD], Fuse) for branch circuit conductors.
27
Ohm's Law and Watt's Law
Expressions of the relationship between current, volt-age, power, and resistance; expressed as Power = Volts X Amps and Resistance = Volts/ Amps
Ohms - V=IR
Watts - P=IV
28
Outlet
a place where current is taken for use; examples include receptacles, light fixtures, and connections at electric appliances such as water heaters.
29
Overcurrent Protection Device (OPD)
a fuse or a circuit breaker; overcurrent protection devices interrupt the flow of electricity when a set current flow is exceeded (an overload), or when a short circuit fault is detected; these devices prevent conductors and devices from overheating and causing fires
30
Panel (panelboard, load center)
the equipment on which circuit breakers or fuses are mounted; panels include associated terminal bars; a panelboard is contained in an enclosure; the first and usually the largest panel is often referred to as the main panel or the service panel; however, there are no generally accepted terms to identify panels
31
Power
A measure of the work performed by electricity; unit of measure is the Watt
The rate at which energy is absorbed or produced within a circuit
32
Raceway
enclosed metallic or nonmetallic components designed and listed for holding conductors or cables between points in the electricity distribution system of the house; examples include various types of conduit and tubing
33
Receptacle
an outlet designed to accept a plug that supplies electricity to an appliance
34
Resistance
The property of a material to allow or restrict the flow of electricity; materials with low resistance are conductors and materials with high resistance are insulators; unit of measure is the Ohm.
R in ohms law
35
Service drop and service lateral:
Service drop and service lateral: the conductors between the transformer belonging to the utility and the house; a service drop is above-ground and a service lateral is below ground
36
Service entrance conductors:
the conductors between the service drop or service lateral and the service equipment.
37
Service equipment
the circuit breakers, switches, or fuses that shut off electricity to the house; all electricity should be shut off using six or fewer circuit breakers, switches, or fuses; often called the main shutoff or main disconnect
38
Service point
the place where the service drop or service lateral conductors end and the house service entrance conductors begin; this is usually at the drip loops for service drops; the service point for service laterals is more difficult to distinguish, but is often at the meter
39
Single phase electrical service
electrical service consisting of two energized 120 volt conductors and one grounded conductor; this is by far the most common residential electrical service
40
Short circuit
this event occurs when current flows between conductors in an unintended manner, such as between the hot and neutral conductors
41
Subpanel
a panelboard that receives power from an upstream panelboard, usually the main panelboard; also called a downstream or a distribution panel; however, there are no generally accepted terms to identify panels
42
Tabs (Twistouts (Knockouts)
rectangular metal pieces on the dead front cover that are removed before installing a circuit breaker; a tab must be replaced by a filler plate if a tab has been removed and no circuit breaker is installed. See Knockouts
43
Terminal bars
metal bars associated with a panelboard on which neutral and equipment grounding conductors (EGCs) are mounted; called a neutral bar when neutral conductors or neutral and EGCs are connected; called a ground bar if only EGCs are connected
44
Three phase electrical service
electrical service consisting of three energized conductors and one grounded conductor; this service type is mostly for commercial and industrial buildings
45
Voltage
the pressure of electricity in a circuit, similar to water pressure in a pipe; unit of measure is the Volt
Ohm's Law = V
46
Wiring Methods
cables and raceways approved for distributing electricity from the service point to panelboards and outlets; examples include armored cable, nonmetallic sheathed cable, and various types of conduit and tubing
47
Updating Electrical System to Current Standards (2 Rules)
1. existing work does not need to be updated if it complied with rules in effect when installed, and if the system or component is functioning safely.
2. new work and existing work that is modified or extended should comply with rules in effect when the work is done.`
48
Bonding occurs when (1, 2, 3)
1. metal that could carry electricity (but is not supposed to),
2. is intentionally connected together to provide a permanent low resistance return path,
3. that is capable of conducting all electricity accidentally carried by the metal back to its source.
49
Ohm's Law
I(current in amps) = E(voltage in volts) / R(resistance in ohms).
V=IR
50
2 Reasons for minimal impact on clearing ground faults (myths)
1. electricity wants to return to ground
| 2. electricity takes the path of least resistance back to its source. It really takes all available paths
51
2 Ways to think about Grounding
1. The grounding system of the house acts like a voltage surge suppressor that helps safely shunt voltage surges to ground.
2. Bonding is a safety system that helps clear ground faults in normally non-current carrying materials.
52
EGCs are really bonding wires (Explain their function)
Their function is to provide a low resistance return path for components like metal switch plates and metal equipment cabinets that may become energized.
53
Grounding electrode system consists of:
1. Grounding Electrode
| 2. Grounding Electrode Condcutor (GEC)
54
GEC should be at least
#4 AWG copper wire is required for ufer grounding electrodes with 200 amp and greater service.
#6 AWG copper for 150 amp and greater
#8 AWG copper wire may be used for 125 amp and smaller service
55
Best way to remember Bonding requirments
if it is metal and it is or could be near electrical wires, then it probably needs to be bonded to the grounded wire of the utility
56
Minimum voltage
Almost all utility-supplied residential electrical service is 240 volt single phase
single phase 120 volt service to a house is usually considered a reportable deficiency
57
Minimum Current
The minimum electrical service current for a modern single-family house is 100 amps.
58
Determining Service Amperage
if the service entrance wires are 2/0 copper (rated for 200 amps), but the service equipment and panelboard are rated for 150 amps, then the service to the house is 150 amps
59
Required and Dedicated Branch Circuits
two-20 amp, 120 volt branch circuits that serve only kitchen countertop receptacles and receptacles in the breakfast and dining rooms; one of these circuits may serve the refrigerator,
•120 or 240 volt branch circuits that serve only one furnace or air handler,
•a 20 amp, 120 volt branch circuit that serves only receptacles in the laundry room,
•one-20 amp, 120 volt branch circuit to serve only receptacles in bathrooms (exception: one 20 amp, 120 volt branch circuit for each bathroom may serve both lights and receptacles in the bathroom
60
What 2 types of kitchen appliances should be on a dedicated circuit
1. Kitchen exhaust fan
| 2. Microwave Oven
61
Service Drop Clearance Above the Roof Minimum Distance
a slope less than 4/12 is 8 feet
a slope 4/12 or greater is 3 feet.
62
Service Drop clearance to Building Openings Minimum Distance:
lowest individual service drop or service entrance conductor and the side or sill of an operable window, door, deck, balcony, or similar point is 3 feet
63
OPDs and wires generate heat, especially ______ and ______.
AFCIs
| GFCIs
64
Location, Access and Working Clearances of Service Equipment
The service equipment, panelboards, and equipment disconnect devices, such as for furnaces and condensers, should be located where access is safe, and should be provided with a safe space around them for inspection and repair.
in front = 36 deep x 30 wide x 78 tall
cabinet door should swing 90 degrees
not higher than 79 inches above adjacent waking surface
65
Service Equipment Working clearance minimum space and accessibility.
36 inches deep, 30 inches wide, and 78 inches tall, measured from the floor.
Equipment should be readily accessible, including a key if locked.
66
Typical Defects, Electical Service
1. service drop conductors in and around tree limbs,
2. damaged service drop and service entrance conductor insulation,
3 .no insulation at service drop connection to service entrance conductors,
4. drip loops inadequate to drain water,
5. loose, bent, or damaged service mast or service head
6. absent, deteriorated, damaged, improperly installed service mast flashing,
7 .loose or damaged service drop connection at house,
8. inadequate clearances between service drop and service entrance conductors and roofs, ground, and building openings,
9. loose, damaged, deteriorated meter bases and electrical enclosures,
10. meter bases and electrical enclosures not sealed where attached to wall coverings, this is a water infiltration point,
11. loose or damaged conduit at or around enclosures,
12. service equipment and panelboard upgraded to larger capacity, but service drop and service entrance conductors not changed.
67
Typical Defects, Grounding and Bonding
1. damaged, disconnected, loose GEC at grounding electrode connection,
2. GEC too small for service (minimum #8 copper for under 150 amp service and #4 or #6 copper for 150 amp or larger service),
3 .absent, loose grounding or bonding clamp,
4. grounding or bonding clamp connected to surfaces that are corroded, painted, dirty, or are covered by other high-resistance contaminants,
5. GEC improperly spliced; GEC may be spliced using a listed compression connector or by welding (not soldering),
6. metallic conduit connected with plastic fittings (electrical connection disrupted),
7. underground water pipe GEC connection located more than 5 feet from where water pipe enters the house (do not confuse this with the water distribution pipe bonding connection),
8. absent, loose, broken metal conduit connections (bonding path interrupted by absent or poor physical or electrical connection),
9. absent, loose, corroded metal water pipe bonding connection,
10. bonding jumper absent around water meter, water pressure regulator, water softeners and filters, and similar removable non-metallic components in metal water distribution pipes,
11. improper bonding connection installed for phone, cable, or similar services,
12. CSST gas tubing not bonded at first metal gas pipe or fitting after gas meter.
68
Name 2 types of risks to Electrical Enclosure Inspection
1. Electrocution
| 2. Arc-flash
69
Purpose of OPDs
1. Interrupt the flow of electricity when excess current is present in the circuit (overcurrent)
2. Interrupt the flow of electricity when a short circuit occurs.
70
Fuses (law of)
Relies on the amount of heat produced by the flow of electric current is based on the amount of current flow, the resistance of the material through which it flows, and time. This is known as Joules Law.
71
Fuses (Name 3 types) and (2 Sub types)
1. Edison base (Type T)
2. Type S base
3. Cartridge
Sub-types
1. Type W open immediatelty when the rate current limit is exceeded. (inappropriate for circuits serving motors)
2. Type L and Type D open with a short time delay (general use)
72
Edison base fuse (older fuse) Name one problem with this type of fuse.
All fuses have the same size base (so a 20 or 30 amp fuse can be easily substituted for a 15 amp fuse). Substituting wrong size could cause a fire.
Note: Edison fuses are no longer permitted for new installations.
73
Fuse color coding (name them)
```
30 amp = green
25 amp = green or yellow
20 amp = orange or red
15 amp = blue or purple
10 amp = yellow or slate (gray)
```
74
How are short circuit faults detected and what is the type of circuit breaker called?
By the intense magnetic field generated by the short circuit. Circuit breakers using this technology are called magnetic-trip circuit breakers.
75
How are overcurrent faults detected and what is the type of circuit breaker called?
By the heat produced by the overcurrent. Circuit breakers using this technology are called thermal-trip circuit breakers.
76
What are modern circuit breakers called
thermal-magnetic-trip circuit breakers.
77
What is the service life of a circuit breaker
Between 30 and 50 years
78
Ground Fault Circuit Interrupters (GFCI) purposes (2) and location
1. protect personnel from shock during a ground fault condition.
2. measure the current flow between the energized and neutral wires and trip if they detect a difference of about 6 milliamperes or more (a ground fault)
```
Located where water may be present, including:
•kitchen countertops,
•bathrooms,
•garages,
•laundry rooms,
•unfinished basements,
•unfinished detached buildings,
•crawl spaces,
•outdoors
```
79
Approved method of substituting a 3-slot receptacle for a 2-slot receptacle in older houses?
Install a GFCI receptacle and label it "NO EQIUPMENT GROUND"
80
Purpose of AFCI circuit breakers
AFCI circuit breakers and receptacles are intended to protect structures from fire caused during an arcing fault condition of the wiring within the wall, the installed switches and outlets, and the equipment plugged in.
81
Difference between GFCI and AFCI
GFCI protect people from shock whereas an
| AFCI protect structures from fire.
82
Does an AFCI combine a GFCI and AFCI into one device (Yes or No)
No
83
Where is the maximum OPD ampcity and Minimum Circuit Ampacity for condensers displayed?
On the Condenser's label
84
Allowed Current for Conductors
The allowed current for #8 and larger copper conductors (#6 and larger aluminum conductors) run in conduit or tubing is different from metallic sheathed cables. .
85
What is the general rule for energized and neutral conductors
One conductor per lug.
86
What is the general rule for EGCs
2 conductors per lug, if the conductors are the same size. (Note: General rules do not apply if mfr's instructions are different.
87
Typical Defects Inside Conductor Enclosures
1. Rust this is an indication of a possible water leak into the enclosure; this could increase resistance and cause an electrical fire.
2. Contaminants such as paint and drywall joint compound in the enclosure this could increase resistance and cause an electrical fire.
3. Damaged conductors and insulation conductors and insulation should be intact; nicked conductors and insulation and multi-strand conductors with absent strands should be cut back to intact material or should be replaced.
4. Melted insulation and charred conductors this indicates a loose connection at the lug or overcurrent that was not interrupted by the OPD.
5. Excess uninsulated conductor at circuit breaker lug no uninsulated conductor should extend past the circuit breaker case
6. Conductors not inserted straight into lugs.
7. Screws with points used to secure enclosure covers points could penetrate conductor insulation and energize the enclosure
8. Wire damaged by screw and taped to repair.
9. Absent or improper handle ties on 240 volt or multiwire branch circuit breakers both conductors of these circuits must shut off together; only approved handle ties may be used; wires, nails, and other improvised handle ties are not permitted.
10. Absent tabs and knockouts this is an electrical shock hazard; tabs and knockouts must be replaced with material similar to the original
11. Low voltage components inside enclosure and conduit low voltage components, such as door bell transformers and telephone and coaxial cable, may not be inside enclosures and conduit containing high voltage components unless the low voltage and high voltage components are physically separated by non-conductive guards
12. Too many circuit breakers on panelboard/half-height circuit breakers in wrong slots the panelboard label states how many branch circuits the panel may serve and which slots, if any, may contain half-height circuit breakers.
13. Panelboard ampacity more than service entrance or feeder conductor ampacity the panelboard label states the minimum ampacity of the supply conductors that should serve the panelboard; the conductors may be larger than the minimum capacity, but not smaller.
14. Cables and conduit not secured to enclosure each cable should enter an enclosure through a cable clamp or within conduit; metal conduit should be connected to the enclosure with a metal fitting or a bonding jumper should be installed.
15. Fused neutral conductors should not be connected to OPDs because in the unlikely event that the OPD opens the neutral conductor, current flow will stop but the circuit will remain energized
16. Panel outer cover removed. Enclosures should be intact with all manufacturer approved parts installed and should be free from physical damage
88
Subpanel Grounding and Bonding (rule). Explain why.
A grounding connection shall not be made to any grounded circuit conductor on the load side of the service disconnecting means. Neutral conductors must be isolated from any equipment grounding conductors (EGCs) and other bonded metal at all points past the service equipment.
The neutral conductor is a current-carrying conductor. Under normal conditions the current is at zero voltage and presents no shock risk
89
Grounding and Bonding (Detached Buildings) served by 2 or more branch circuits/feed conductors to a subpanel require installation of what?
Grounding electrode system
90
New brtanch circuits and feedeers that served detached buildings should contain a(n) ____. the EGC should be connected to the _________ _________. The neutral conductors should be isolated from the EGC and from any subpanel enclosuure.
EGC.
| Grounding electrode.
91
Typical Defects, Subpanels.
1. EGCs and neutral conductors are connected to the same terminal bar.
2. EGCs or EGC terminal bar is not bonded to enclosure.
92
Armored Cable (AC) is sometimes called __. however, __is a brand name now owned by General Electric, so only some AC is __ brand. The best description of this wiring method is AC or armored cable.
BX
93
AC should be supported every __ foot/feet and within ___ foot/feet from boxes and terminations
AC
4-1/2 feet supports
1 foot from boxes and terminations.
94
Electric Metallic Tubing (EMT) is sometimes called ____ _____. Give definition and common size range.
Thin Wall. Round pipe designed for routing and protection of conductors and cables. Common size range is from 1/2 to 4 inches in diameter, and it comes in 10 foot sections.
95
EMT should be supported every __ feet and within ___ feet from boxes and terminations.
EMT
10 feet supports
3 feet from boxes and terminations.
96
Electrical Nonmetallic tubing (ENT) definition and common size range.
ENT is a flexible corrugated tube designed for routing and protection of conductors and cables. Common sizes range from 1/2 to 2 inches diameter.
97
ENT should be supported every __ feet and within ___ feet from boxes and terminations.
ENT
3 feet supports
3 feet from boxes/terminations
98
Flexible Metal Conduit (FMC) definition and common size range
FMC is a flexible tube made of helically wound interlocking metal designed for routing and protection of conductors and cables.
Common sizes range from 1/2 to 4 inches diameter.
99
FMC should be supported every __ feet and within ___ feet from boxes and terminations.
FMC
4-1/2 feet supports
1 foot from boxes/terminations
100
Intermediate Metal conduit (IMC) and Rigid Metal Conduit (RMC) definition and Common sizes range.
IMC and RMC are round pipes designed for routing and physical protection of conductors and cables. Common sizes range from 1/2 to 4 inches.
101
IMC and RMC should be supported every __ feet and within ___ feet from boxes and terminations.
IMC and RMC
4-1/2 feet supports
1 foot from boxes/terminations
102
Metal-Clad Cable (MC) is sometimes called ________. Common size range are around ___-inch diameter.
Greenfield.
| Size range 1/2-inch diameter
103
MC should be supported every __ feet and within ___ feet from boxes and terminations.
MC
6 feet supports
1 foot from boxes/terminations
104
Nonmetallic sheathed Cable (NM) and Underground Feeder (UF) is the predominant wiring method in most houses in most markets since the 1940's (True or False).
True.
105
Nonmetallic sheathed Cable (NM) and Underground Feeder (UF). NM is sometimes called _____.
Romex.
106
Early versions of NM may be found in houses from the late late 19__s to the early 19__s. Early versions of NM had ____ sheathing instead of PVC sheathing.
NM
1920s to 1960s.
Cloth instead of PVC.
107
The difference between UF and NM sheathing.
UF is designed for wet locations and may be buried. The jacket covering UF is usually gray. UF may not be used for swimming pools, hot tub and spa wiring because UF's EGC is uninsulated.
108
```
NM jacket color coding:
White
Yellow
Orange
Black
```
White=#14
Yellow=#12
Orange=#10
Black=#8 and #6
109
NM should be supported every __ feet and within ___ feet from boxes and terminations.
within ___ inches of most plastic boxes.
Flat NM should be ______ with the flat side toward the framing member.
```
NM
4-1/2 feet supports
1 foot from box/terminations
Within 8 inches of plastic boxes.
Flat NM should be stapled.
```
110
NM #10 and smaller should be installed where?
through holes in basement floor joists; it should not be attached to the bottom of floor joists.
111
Rigid Polyvinyl Chloride Conduit (PVC) PVC is a
1. round pipe designed for routing and protection of __________ and _______.
2. It used to be called ______ __________ ______
3. Comes in 2 wall thicknesses Schedule __ and Schedule ___.
4. Schedule 80 should be used when protection against _________ ______ is necessary.
5. PVC conduit is not the same as PVC _________ pipe.
PVC
1. Conductors and Cables.
2. Rigid Nonmetallic Conduit (RNC)
3. 40 and 80
4. Physical damage.
5. Plumbing
112
PVC should be supported every __ feet and within ___ feet from boxes and terminations.
PVC
3 ft supports 1" & smaller
5 feet for 1-1/4"+
3 feet from box/terminations
113
Service Entrance Cable (SE) is used as the service entrance ________ between the service point and the service equipment.
SE
| Act as Conductors between the service point and the service equipment
114
SE should be supported every __ inches and within ___ inches from boxes and terminations.
SE
30 inches supports
12 inches from boxes/terminations
115
Bend radius Wiring method bends should not damage the component. The internal diameter of conduit and tubing should not be reduced. The bend radius of cables such as AC and NM should not be less than ____ times the cable diameter
Bend radius
| Not less than 5 times the cable diameter.
116
NM Cable Burial Depth. Wiring method burial depth should be deep enough to reduce the chance of accidental damage and the resulting shock hazard that can occur during excavation. The usual burial depths are for:
1. UF and MC: at least ___ inches.
2. RMC and IMC: at least ___ inches.
3. PVC, LFMC and LFC: at least ___ inches.
4. GFCI protected residential branch circuits at 20 amps or less may be buried at least ___ inches regardless of the wiring method.
NM Cable Burial Depth
1. UF and MC: 24 inches
2. RMC and IMC: 6 inches
3. PVC, LFMC and LFC: 18 inches
4. GFCI protected; 12 inches
117
Flexible Cords are
1. made from ____________ _______________
2. terminate with an _____________ ______.
3. intended to connect an appliance to an _____ that is usually a receptacle.
Flexible cords are cables that are usually: (1) made from stranded conductors, (2) terminate with an attachment plug, (3) intended to connect an appliance to an outlet that is usually a receptacle
118
Flexible cords may not be installed:
1. within or through ______
2. _______
3. _____
Flexible cords not installed:
1. Walls
2. Ceilings
3. Floors
119
The maximum flexible cord length is
1. ___ inches for a food-waste disposer,
2. ___ inches for a range hood and a trash compactor,
3. ___ inches for a built-in dishwashing machine
1. 36 inches--food waste disposer
2. 48 inches--range hood/trash compactor
3. 78 inches--built in dishwasher
120
Subject to Physical Damage
The term subject to physical damage is often used regarding ______________ ____________. Cable installed within __feet vertically and __ feet horizontally from an attic access opening is considered subject to physical damage
Electrical components
7 feet vertically
6 feet horizontally
121
Typical Defects, wiring Methods Typical defects that home inspectors should report include:
1. splices and taps not contained within an approved and covered box,
2. box does not have an approved cover,
3. box knockout does not have an approved cover,
4. cable enters box without intact sheathing, at least ¼ inch of sheathing should enter the box,
5. junction box concealed (usually not visible),
6. wiring method not properly secured near box or enclosure or not secured along run,
7. wiring method not protected against physical damage,
8. wiring method installed outside and not approved for outside installation,
9. NM and AC cable installed outside or in buried conduit,
10. cable or conductors enter metal box without cable clamp or busing,
11. metal box not grounded (bonded),
12. wiring method deteriorated or damaged,
13. cable or conductors repaired with electrical tape or with other unapproved material,
14. conduit loose at or around enclosures,
15. extension cord used as permanent wiring,
16. attachment plug provides electricity to permanent wiring method,
17. flexible cord passes through or installed in a ceiling, wall, or floor.
122
Knob and Tube Description
Knob and tube wiring gets its name from the ______ insulators used to support the conductors and from the ______ tubes used to protect conductors when they ran through framing members.
Thermal insulation-covered knob and tube may be damaged by _____ traffic.
Thermal insulation-covered knob and tube is a reportable _________ in most areas.
Contact between knob and tube and ______ is a major reportable deficiency.
```
Knot and Tube:
Ceramic Insulators
Ceramic Tubes
Attic Traffic
Reportable Deficiency
Metal
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123
Correct knob and tube Installation Correctly installed knob and tube wiring should have these characteristics. Knob and tube wiring that does not comply with these is a reportable deficiency.
1. At least 1 inch distance between the wires and objects like walls, floors, and framing.
2. At least 3 inches distance between the wires.
3. Not more than 6 inches between knobs and a wire splice, including splices in boxes.
4. Not more than 4 ½ feet between knobs in wire runs.
5. Wires run on the sides of joists, rafters, and studs, not on top.
6. Tubes installed where the wires penetrate framing.
7. Taps between knob and tube wires and other knob and tube wires may occur outside of covered junction boxes. The taps should be soldered and taped using friction tape.
8. Taps between knob and tube wires and other wiring methods should occur inside a covered junction box or conduit body.
9. Wiring methods should enter boxes with appropriate protection and should be secured near the box as required. Each knob and tube wire should enter the box through a separate opening protected by a bushing. NM cable should enter the box through a clamped opening and should be secured within 12 inches from the box.
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Knob and Tube Problems.
1. It usually has no ___.
2. It is a __ amp circuit and may have more lights and receptacles connected to it than is safe.
3. Potential _______ containing material.
1. No EGC
2. 15 amp circuit
3. Potential Asbestos containing material.
125
Cloth Covered NM Problems
1. Cloth-covered NM can be found in houses from late 1920s, but is more likely to be found in houses built during the 19__s and 19__s.
2. It gets its derogatory nickname, ____ ____ from its cotton or rayon sheathing.
3. ______ like to chew on the cloth sheathing.
4. Lack of ____.
1. 1940s and 1950s
2. Rag wire
3. Vermin chew.
4. No EGC.
126
Solid Conductor Aluminum Wiring
1. in ____ they started making solid-conductor aluminum wiring in #8 - 12 AWG nonmetallic sheathed cable intended for residential use
2. A ______ ______ (electrolysis) occurs when different metals are in contact in the presence of moisture.
3. It expanded more than _____ when the wire got hot.
4. Expansion and contraction caused the wire to ______ at connections.
5. Wires worked loose at _______ and _______ connected from the back instead of using the side screws.
6. over multiple expansion and contraction cycles, aluminum wire at the connections would become distorted, smaller, and brittle, permanently. Some call this problem ____ _____ while others call it _________.
7. By ___, though, solid-conductor aluminum wire had gotten such a bad reputation that nobody wanted it. Manufacturers stopped making it.
8. The next attempt was devices labeled CO/ALR. These devices work and have been required by the NEC since ___.
9. COPALUM connector. This uses a patented connector and crimping tool to ____ ____ copper wire to aluminum wire. This process has been around for years and is recommended by the Consumer Product Safety Commission (CSPC) = EXPENSIVE
10. AlumiConn has been available since the early ____'s and is recommended by the CSPC
11. it is important not to ____ all aluminum wire with the same brush.
12. stranded aluminum wire is available in AWG sizes ___ and larger and is used for large appliance branch circuits and for service entrance and feeder wires.
1. 1964.
2. Galvanic reaction
3. copper
4. loosen
5. Receptacles and switches
6. Cold flow or Creep.
7. 1980
8. 1981
9. Cold Weld
10. 2000s
11. PAINT
12. AWG #8
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Using anti-oxidant paste at terminals is highly recommended. Anti-oxidant paste is also highly recommended where aluminum and copper wires are connected together. Anti-oxidant paste is not specifically required by the National Electrical Code (NEC).
True or False.
True
| Anti-oxidant paste is NOT specifically required by the NEC
128
Copper-clad aluminum wire was produced in the 1970s. It looks like copper wire except you can see the ________ wire where the wire is cut Copper-clad aluminum wire is rated as _______ wire when determining wire ampacity
Aluminum
| Aluminum
129
Copper-Clad Aluminum Wiring
1. Tin-coated copper wire was most popular in the ____s and _____s.
2. Houses built before ____ might contain solid-conductor aluminum wire, but it is unlikely.
3. If the insulation is ______, it is not tin-coated copper
4. All tin-coated copper wire is near the end of its expected service life. The old ______ insulation can crack and fail, especially when distrubed.
1. 1940s and 1950s
2. 1964.
3. Plastic
4. Rubber
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Receptacles
1. The 120 volt receptacles will be the 3-slot grounded polarized receptacle
2. The 240 volt receptacles will be the 4-slot grounded receptacle
3. In older houses, some 2-slot receptacles may remain as will 3-slot ungrounded 240 volt receptacles
4. A polarized receptacle is one in which a slot is a different size or orientation
5. Polarized receptacles help keep metal on devices such as lamps from becoming energized
polarized 120 volt receptacles have the neutral slot on the left, the energized slot on the right
modern 120 volt receptacle is the duplex receptacle, so called because it can accommodate two plugs
6. Interior receptacles may be installed in floors (with listed floor boxes), in ceilings, or anywhere in between
Loose receptacles are a common defect, especially receptacles mounted in bathroom mirrors.
7. Loose receptacles are a common defect, especially receptacles mounted in bathroom mirrors
8. install a GFCI receptacle and label it "NO EQUIPMENT GROUND.
9. This is sometimes called a bootleg ground
10. potential shock hazard because it places electric current into the grounding system
11. One fixed in place appliance should not exceed 50% of a general lighting branch circuit amperage rating
131
Room Receptacles.
1. Receptacles serving walls in habitable rooms should be spaced so that no point along the wall is more than 6 feet from a receptacle
2. Wall space includes any wall more than 2 feet wide, fixed panels of doors, partial height walls, and room dividers such as railings. Wall space does not include obstructions such as fireplaces and closets
3. Floor receptacles may be used to comply if the receptacle is within 18 inches from the wall
4. Receptacles may not be more than 66 inches above the floor if they serve as a required receptacle
132
Kitchen Countertop receptacles
GFCI protected receptacles serving walls above kitchen countertops should be spaced so that no point along the wall above the countertop is more than 2 feet from a receptacle
133
Kitchen Island and Peninsula receptacles
1. At least one GFCI protected receptacle should be located at a peninsula if it measures more than 2 feet long (measured from the perpendicular wall closest to the peninsula) and 1 foot wide
2. If the island contains a sink or cooking appliance, the kitchen countertop wall receptacle requirements apply
3. The required receptacles may be mounted on the cabinet if the receptacle is not more than 12 inches below the countertop and if the countertop does not extend more than 6 inches past the cabinet above the receptacle.
134
Bathroom receptacles
1. At least one GFCI protected receptacle should be located within 3 feet from the outside edge of each bathroom sink.
2. At least one GFCI protected receptacle should be located within 3 feet from the outside edge of each bathroom sink.
135
Outdoor Receptacles
At least one GFCI protected receptacle should be installed within 78 inches vertically from the walking surface (grade) at both the front and rear of the house
136
Laundry Receptacles
At least one GFCI protected receptacle should be installed in the laundry.s HVAC.
137
Hallway Receptacles
At least one receptacle should be installed in a hallway that is 10 feet or more long when measured along the center of the hallway.
138
Foyer Receptacles
Receptacles should be installed in a foyer with an area more than 60 square feet. A receptacle should be installed in each wall space that is at least 3 feet wide and is not interrupted by doors, tall windows, and similar openings.
139
Unfinished Basement Receptacles
At least one GFCI protected receptacle should be installed in an unfinished basement. This is in addition to receptacles required for appliances such as HVAC
140
Garage and Accessory Building Receptacles
At least one GFCI protected receptacle should be installed in each vehicle bay of an attached garage, and in any detached garage if it is provided with electricity.
141
HVAC Service Receptacles
At least one receptacle should be installed within 25 feet from and on the same level as HVAC equipment such as furnaces and condensers.
142
Wet Area Receptacles
Receptacles installed in wet areas should have a cover that is weatherproof when a plug is inserted. These covers are sometimes called bubble covers
143
Typical Defects, Receptacles Typical defects that home inspectors should report include:
1. loose receptacles (e.g., receptacle moves when plug inserted),
2. damaged, scorched, aged/worn, or painted receptacles (e.g., plug falls out of receptacle),
3. absent, damaged, or loose cover plates,
4. gap between receptacle and cover plate or between cover plate and wall,
5. damp or wet area cover not installed where required, or cover damaged,
6. receptacle connected to an improper branch circuit, (e.g., receptacle not in a bathroom is on the bathroom branch circuit),
7. inadequately supported boxes,
8. improperly wired receptacles, (e.g., reverse polarity, not grounded, open neutral),
9. no power at receptacles,
10. receptacle ampacity rating not compatible with branch circuit,
11. receptacle not installed where required, (e.g., kitchen countertop receptacles too far apart),
12. receptacle installed where not allowed, (e.g., above bathtub,
13. receptacles not AFCI or GFCI protected where required.
144
Switches
1. In modern houses, most switches are either snap switches or rocker switches
2. Several dimmer styles are available including rotary, push button, and slide
3. Light fixtures controlled from two locations require a 3-way switch in both locations
4. Light fixtures controlled from three or more locations require a 3-way switch at each end of the circuit and 4-way switches in the middle
5. Home inspectors should test 3-way and 4-way switches from all locations.
6. Boxes supported by conduit should be supported by at least two pieces of conduit. The conduit should be secured within 18 inches of the box
7. Appliance Disconnects. Fixed in place appliances should have a means to disconnect electricity to the appliance for the safety of service personnel. The fuse or circuit breaker at a panelboard is always an acceptable disconnecting means if the panelboard is in sight of the appliance
145
Typical Defects, Switches Typical defects that home inspectors should report include:
1. loose switches (e.g., switch moves when operated),
2. damaged, scorched, aged/worn, or painted switches (e.g., switch makes noise (arcs) when operated,
3. absent, damaged, or loose cover plate,
4. gap between switch and cover plate or between cover plate and wall,
5. damp or wet area cover not installed where required, or cover is damaged,
6. inadequately supported switch box,
7. no power at switch,
8. 3-way and 4-way switches do not function properly in all switch positions,
9. dimmer switches do not function properly,
10. switch installed where not allowed (e.g., above bathtub),
11. switch operates intermittently,
12. switch unusually warm,
13. switch appears to control a load greater than its ampacity rating,
14. switch installed upside down,
15. switch located behind a door or in another inconvenient location.
146
Light bulbs (lamps) come in five common types
1. Thomas Edison invented the incandescent bulb
2. Compact fluorescent bulbs (CFLs) Complaints about CFLs include that some take time to emit the full light output and that they contain mercury, a hazardous material.
3. Light emitting diode bulbs (LEDs)
4. Fluorescent
5. Halogen
147
In new homes, at least 75% of the light bulbs should be high-efficacy bulbs.
Examples of these bulbs are: CFLs, LEDs, and fluorescent
148
Lighting branch circuits in houses are restricted to 15 or 20 amps, 120 volts
Low voltage lights are especially common in landscape lighting. Low voltage lighting is out of scope of a home inspection regardless of where the lights are located.
149
Light fixture Installation
Light fixtures that weigh not more than six pounds may be supported by most boxes Light fixtures that weigh more than six pounds should be supported by a box listed for support of heavier light fixtures. These boxes should be secured directly to framing or should be secured to metal bars that are secured to framing.
150
Required Lights
1. A wall switch-controlled light should be located in every habitable room and bathroom
2. A wall switch-controlled permanent ceiling or wall fixture should be located in every hallway, interior and exterior stairway, attached garage, detached garage where electricity is supplied, and at exterior doors
3. The switch should be near the entrance to the space. The light may be located anywhere in the space except the light should be near the equipment, if any
151
Lights Near Tubs and Showers
Hanging light fixtures, track lights, and ceiling fans should have no parts located within a zone from 3 feet horizontally and 8 feet vertically from the tub rim or shower threshold
152
Lights in Clothes Closets
A clothes closet is one that contains shelves or rods designed for storage of clothing. Pantries and similar storage closets are not included in this section. A clothes closet is divided into two storage areas. The hanging rod storage area extends vertically from the floor to the highest rod or 6 feet, whichever is higher, and horizontally 2 feet from the walls. The shelf storage area extends vertically from the highest shelf to the ceiling, and horizontally from the widest shelf or 12 inches from the wall, whichever is larger.
All distances are measured to the storage area, not to the shelf or to the rod
Light fixtures with exposed incandescent bulbs should not be located anywhere in a clothes closet.
Surface-mounted fluorescent fixtures and recessed incandescent, LED, and fluorescent fixtures should not be located within 6 inches from the closet storage areas.
153
Ceiling Paddle Fans
1. Ceiling fans are not light fixtures; they are appliances.
2. Unbalanced ceiling fans are a reportable defect.
3. Operating the fan by remote control is out of scope of a home inspection
4. Home inspectors should report that a fan was not operated if operation is only by remote control and if the remote control was not located.
154
Recessed Lighting
Some recessed lights are insulation contact (IC) rated and some are not.
Recessed lights that are not IC rated should have at least 3 inches of space between the light and insulation.
155
Typical Defects, Light Fixture and Ceiling Fans Typical defects that home inspectors should report include:
1. loose fixture or fan,
2. damaged, scorched, aged, fixture or fan
3. absent parts,
4. exposed conductors in a fixture or fan box,
5. gap between light fixture and wall or ceiling,
6. damp or wet area fixture not installed where required,
7. interior fixture or fan installed outdoors,
8. inadequately supported fixture or fan,
9. fixture or fan does not function using nearby switches,
10. hanging fixture or ceiling fan too close to tub or shower,
11. fixture too close to clothes closet storage area,
12. exposed incandescent bulb in clothes closet,
13. recessed light operates intermittently,
14. ceiling fan unbalanced, wobbles.
156
Smoke Alarm and Carbon Monoxide Alarm Inspection
1. Standards of practice usually require only that the home inspector report the presence or absence of smoke alarms and carbon monoxide alarms
2. The IRC requires updating smoke alarms and carbon monoxide alarms to current standards when work requiring a permit is performed.
3. The smoke alarm update exceptions involve exterior work such as roof coverings and wall claddings, and work involving only plumbing and mechanical systems.
157
False (Nuisance) Alarms
1. show by the color of the indicator where the power is from (for example, green = house power and red = battery)
2. testing alarms and reporting the results can be a case where no good deed goes unpunished.
3. There are UL listed aerosol smoke products for testing smoke sensors,
158
Alarm Service Life
1. Many smoke alarm manufacturers recommend replacing smoke alarms after about ten years.
2. Carbon monoxide alarms have a shorter service life of around five to seven years.
159
Smoke Alarm Locations
1. The minimum requirement of a smoke alarm in each bedroom and in the hallway near the bedrooms is widely known
2. The ideal smoke alarm location is on the ceiling at least 4 inches away from the wall
3. Smoke alarms should not be installed near combustion sources such as in garages and near combustion equipment such furnaces, boilers, water heaters, and fireplaces of all types
4. Nuisance activation is also common when smoke alarms are installed kitchens, so they should not be installed there.
160
Carbon Monoxide Alarm Locations
1. In new construction, at least one carbon monoxide alarm is required in houses with a fuel-burning appliance and in houses with an attached garage
2. The alarm should be located near the bedrooms and if the bedrooms are widely separated or are on different stories, then multiple alarms are required.
161
Alarm Installation
Smoke alarm and carbon monoxide alarm installation requirements include: (1) connection of all smoke alarms to each other such that if one alarm is activated all alarms sound (interconnection may be hard wired or wireless), (2) primary power provided by the utility power to the building, (3) back-up power provided by a battery in case the fire disrupts the utility power to the building. Carbon monoxide alarm interconnection is a new requirement, so most houses will not comply.
162
Load Controllers
A load controller is a device that allows the electric utility to temporarily disconnect the electricity to a device during peak demand
Load controllers are out of scope of a home inspection
163
Generators
Generators and all associated components are out of scope of a home inspection.
Home inspectors should report the presence of a generator, and of any related components such as a transfer switch, disclaim inspection, and recommend specialist evaluation to determine the condition and functioning of a generator system.
164
Transfer Switch
A transfer switch is required to disconnect the house from the grid while the generator is providing electricity to the house
A transfer switch disconnects the house electrical system from the grid and provides electricity to selected branch circuits when the generator is providing electricity.
165
Alternative Energy Systems
Alternative energy systems (also called renewable energy sources) are usually defined as systems that provide electricity, heat energy, or energy of motion using means other than combustion of fossil fuels (e.g., oil, gas, coal)
•solar photovoltaic (PV),
•wind turbines,
•solar water heating,
•passive solar design,
•ground-source heat pumps (commonly but inaccurately called geothermal systems),
•water-source heat pumps.
Few, if any, alternative energy systems may be legally installed without a permit
Alternative energy systems and all associated components are out of scope of a home inspection
Home inspectors who elect to report about these systems should disclose the limitations of their inspection and reporting
166
Solar Photovoltaic Systems
Solar photovoltaic (PV) systems use light from the sun to produce direct current (DC) electricity
Other components of a PVC system include:
•conduit, electrical metallic tubing (EMT) and metal-clad cable (MC) are common, but other types of conduit and tubing may be acceptable if listed for use where installed; conductors should be run in conduit except where entering or leaving equipment or when necessary to allow movement of an array,
•conductors, may be single conductors or multiple conductor cables if listed for use where installed,
•mounting hardware appropriate for the modules installed,
•waterproofing components where components penetrate roofs and walls.
Other PV system requirements include:
•PV conductors should be identified as such where accessible,
•PV conductors should not be installed in the same conduit or tubing as conductors from other systems, except where the PV conductors connect to other systems,
•conduit, tubing, and boxes containing PV conductors should be labeled as such, this is a newer requirement so older systems may not comply,
•exposed non-current-carrying metal parts of the PV system should be grounded,
•at least two 36 inch wide pathways should be provided on separate roof planes for access by emergency personnel, at least one of these should be on the street side, this is a new requirement so most systems will not comply,
•arrays should be set back from a roof ridge either 18 or 36 inches depending on how much of the roof area is occupied by arrays, this is a new requirement so most systems will not comply.
Service Life Traditional solar panels should function for between 20 and 25 years, although output declines with age. Older panels are still functioning, and panels over 50 years old have been reported to be functioning. Inverters should function for between 5 and 15 years. The remaining components should function for between 30 and 50 years.
Typical Defects Typical defects that home inspectors may report include:
1.PV system disconnected or not functioning (display on inverter usually shows system status),
2.backfed PV circuit breaker not secured in panelboard,
3.components not labeled,
4.absent disconnect switches,
5.exposed conductors (except where intended),
6.array tracking module not functioning (difficult to determine during a home inspection),
7.metal components not bonded, or gaps in component physical or electrical connection,
8.panels cover vents and exhaust terminations (okay if space between panel and vent or termination at least as large as the opening),
9.damaged panels including scratches on glass,
10.significant shading of arrays (may be accounted for in the system design).
167
Wind Turbine Systems
Other wind turbine system requirements include that a surge protective device (lightning arrestor) should be installed between the wind turbine system and loads served by the house electrical system, and that the tower be connected to a grounding electrode.
Wind turbine towers are either self-supporting or supported using guy cables. Guyed towers are less expensive, but require more land to install the guy cables. Some towers can be raised and lowered to allow easier maintenance of the rotor and generator module.
Typical Defects:
1. wind system disconnected or not functioning (display on inverter usually shows system status),
2.backfed wind circuit breaker not secured in panelboard,
3.components not labeled,
4.absent disconnect switches,
5.exposed conductors (except where intended),
6.metal components not bonded, or gaps in component physical or electrical connection,
7.tower not grounded,
8.damaged or deteriorated components,
9.surge protector not installed.
168
Solar Water Heating
System Components Solar water heating system components include:
•a collector,
•a storage tank (may be the collector in a batch system),
•insulated pipes,
•a temperature limitation system to limit the temperature of fluids entering or exchanging heat with a pressurized vessel inside the building to not more than 180° F,
•valves to isolate the solar water heating system from the rest of the domestic hot water system,
•a backflow preventer,
•labels as required by local standards.
Typical Defects Typical defects that home inspectors may report include:
1.system disconnected or not functioning (improper functioning may be difficult to visually determine),
2.absent backflow preventer,
3.absent or improperly installed pressure relief valve, temperature/pressure relief valve, or extension pipe,
4.absent, improperly installed, or deteriorated pipe insulation,
5.leaks from or inside collector, and leaks from pipes,
6.damaged or corroded components,
7.absent expansion tank where required,
8.shading of collector,
9.dirt on collector,
10.leaks at roof mounts (for roof-mounted collectors),
11.deformed roof framing (roof-mounted collectors filled with water are heavy),
12.absent labels where required, such as at on collectors, on storage tanks, and at drain and fill valves.
Standards (1) IRC 2018 Chapter 23; (2) manufacturer's instructions.
