Wiring Electrical Panels - 4 Flashcards
What is the purpose of fuses and circuit breakers?
to protect components against overcurrent.
What is NOT the purpose of fuses and circuit breakers on an electrical system?
Fuses and circuit breakers do not protect people working on the system.
What is the purpose of an electrical grounding circuit?
To prevent shock hazards that can occur from touching metallic parts of an electrical system.
What is electrical grounding the process of?
the process of using conductors to connect an electrical system to earth ground.
NEC Grounding Standards
Grounding the electrical system involves connecting metal parts that do not normally carry current to the system’s grounded conductor.
What are junction boxes used for in ground connections?
Junction boxes are often used to connect the external device grounds to the panel ground circuit.
If panels don’t have a ground bar, each ground is connected, by ground wire, to the what?
Main panel’s ground block.
The NEC requires conductors used in grounding systems to have what? (3 Answers)
- A Conductor made of copper, aluminum, or copper-clad aluminum
- Conductor is solid or stranded
- Insulation is green or green with yellow stripes
What are three types of ground connectors are there?
- Ground screw
- Ground Bar
- Ground Terminal Block
What should you do once a ground system is installed
Inspect and test before operation.
What is the first part of inspecting a grounding system?
a visual check of the ground wires.
What is the second part of inspecting a grounding system?
Check continuity with resistance setting using a DMM. (There should be continuity on all ground connections.)
What is the function of Wireways?
Wireways provide a channel through which wiring is routed between the electrical panel components. To keep it organized.
Wires should exit the wireway as close as possible to the ________.
Component.
What do wireways use to help protect the wiring and give the inside of the control panel a neat appearance?
Covers.
How many control devices are needed to make wireways not required in the control panel?
Less than six.
What are two methods of connecting wires to screw terminals?
- Straight wire method
* Lug connector method
What are the steps of the straight wire method?
- Strip a piece of insulation from wire.
- Twist end of wire if it is stranded.
- Placed stripped piece of wire under terminal clamp.
- Tighten screw to secure the clamp on the wire.
What are the steps of the lug connector method?
- Strip a piece of insulation from wire.
- Crimp a lug connector onto the stripped portion of wire using crimping tool.
- Attach lug under screw or clamp.
- Tighten screw to secure the the wire.
Where are wires terminated?
Inside an electrical panel at a terminal block or a component.
What must you do before terminating a wire?
The insulation at the end of the wire must be removed using a stripping tool.
What two types of wire stripping tools can you use?
- Manual Wire Strippers
* Automatic Wire Strippers
What happens if you nick the solid wire when stripping?
The mechanical strength of the wire gets reduced. May also cause the wire to break when connected.
If solid wires are nicked or strands are cut during the stripping process, what do you do?
Cut of the stripped portion of the wire and strip the wire again.
What are three important rules when terminating wires?
- Avoid Exposed Wires
- Avoid Clamping Insulation
- Wire Label Orientation (Should be properly set)
What helps identify connections between components when using an electrical print?
Wire number labels.
When running wires between panels, all wires are fed through the _______ together in order to keep the wires from being tangled.
Conduit.
What are two methods of identifying wires?
- Wire Label Method
* Continuity Test Method
Why is the wire label method used?
It is commonly used when the longest wire length is less than five feet.
What are the steps of the Wire Label Method?
- Determine the number of Wires between panels
- Determine the Longest Run Length
- Cut the wires
- Number and Connect Wires to the Terminal Block
- Number the Other End of the Wires
- Feed the Wires through the conduit
What are the steps of the Continuity Test Method?
- Determine the number of wires between panels
- Determine the longest run length
- Cut the wires
- Number and connect wires to the terminal block
- Feed the wires through the conduit
- Connect a Wire to ground
- Use DMM to identify the wire inside the other panel
- Connect the wire to the terminal block inside the other panel.
What the two methods of feeding wires through conduits?
- By Hand
* By Fish Tape
What is the function of wire bundling?
Wire bundling keeps the wiring system organized and some methods provide extra strength.
What are three common methods used for bundling wires inside an electrical panel?
- Wireways
- Wire Ties
- Wire Sleeves.
What are wireways?
Wireways provide channels through which wires are run.
What do wireways require compared to other bundling methods?
More space inside the panel.
What are wire ties?
Wire ties are a low cost and simple method of bundling wire in an organized way.
What are wire sleeves?
Wire sleeves are jackets that are wrapped around bundles of wire to keep them in place and provide protection.
What do you need to do to wire a motor?
The motor leads must be spliced to the power leads.
Where do you splice?
Inside the wire housing on the motor.
What are the steps to splice motor wires?
- Pull out the motor leads out of the wire’s housing cover.
- Strip the ends of the motor leads and crimp ring lugs onto the ends.
- Using motor manufacturer data, the wire configuration should show which leads are spliced together.
- Connect the power and motor leads together according to the wire config. by bolting the ring lugs together.
What do you do when you have an exposed portion of wire?
Must be taped.
How many layers of tape are needed for every 100 volts of the insulation rating?
1.
How many millimeters should the tape overlap each turn?
6.25mm (0.25 in.)
Are motor leads connected to power leads inside the junction box between the control panel and motor? (TRUE/FALSE)
FALSE.
Separate ________ ______ are used inside the control panel for control wiring and power wiring.
Terminal blocks.
What are the five steps of connecting motor power leads to the control panels?
- Prepare the Wires
- Connect the wires to the control panel terminal block
- Feed wires through conduit
- Connect Wires from Control Panel inside junction box
- Connect motor wires inside junction box
What are the two steps used to ensure the proper operation of the system after all the motor control wiring is connected?
- Verify Wiring Connections
2. Verify System Operation (Examine prints, record what to expect, power up the system, and more)
With what do you verify wiring connections, and what setting?
A DMM, continuity.
How do you verify system operation?
Examine prints, record what to expect, power up the system and run the control circuit in automatic mode to verify.
