n you run thhn wire in a cable tray
School question. The answer can be found in your electrical code book.
The conductors of any three phase circuit must be run in the same conduit. If the circuit requires a neutral, it must also run with the conductors in the same conduit. (If they were to be run in more than one conduit or raceway, the circuit would not operate properly.)
Need to know what size service is going to be installed at the end of the run.
No, the bare copper grounding conductor can not be in a conduit with other conductors. It can be in conduit by itself to provide mechanical protection for the wire.
An underground electrical pull box provides another access point in long runs of cable to make it easier to pull the conductors from one end of the run to the other. The crew can only slap so much silicone lube on the conductors and the the conductors can only have a limited amount of force applied on them to pull them through the conduit. If a long run is broken up somewhere in the middle, the crew can pull to that point where the pull box is located, and then "start a new pull" from the box to the end of the run. It's more work, but it protects the conductors and the job ends up "meeting code" and passing inspection.
yes
9
THHN is a heat resistant thermoplastic insulated conductor, usually a single conductor. Romex is a brand name for a nonmetallic sheathed cable, it has multiple conductors inside, the insulated ones are insulated with THHN insulation.
According to the 2005 NEC Annex C, table C.1 you are allowed nine #12 THHN conductors in a 1/2" trade size EMT conduit. If your conduit run is any length at all, you would be wise to increase the conduit size to 3/4". as pulling 9 #12's for any length in 1/2" EMT is very difficult.
#8 aluminum thhn 90 degree wire is rated at 30 amps. Remember to de-rate the wire for more that three conductors in a raceway and the second de-rate for the ambient temperature. Most students miss the de-rate for more that three conductors in a raceway.
That depends on the size of the conductor and the type, which is defined by its insulation. With many common large feeder conductors such as THHW, the largest conductor which you can run 8 of is # 2 gauge. Whereas common small branch circuit conductors such as # 12 THHN, you can run 138 ea. through a 2 " conduit. For the complete list, look at the chart titled "Maximum number of conductors in electrical metallic tubing" (EMT) in the National Electrical Code.
Exposed THWN (Thermoplastic High Heat-resistant Nylon-coated) conductors are not suitable for use as they are not rated for exposure to the environment. This can lead to safety hazards such as electrical shocks or fires. It is essential to follow proper installation practices to ensure the safety and longevity of electrical systems.
School question. The answer can be found in your electrical code book.
9 - Is this a test answer or do you just want to know for a project you're doing? Take a look at NEC chapter 9 - tables 4 and 5 (in the 2005 edition at least)
For five runs of #12 AWG conductors, a minimum of 1 inch PVC conduit would be required to meet the fill ratio requirements, providing adequate space for the conductors while allowing for future additions or modifications.
THHN wire is a single-conductor wire used for commercial and industrial applications, while Romex wire is a type of electrical cable with multiple conductors used in residential settings. Romex wire is more suitable for residential electrical wiring due to its ease of installation and protection against damage.
Insulation tape is used to protect exposed electrical conductors or wires. Another term for it would be electrical tape. It is wrapped around wires and other electrical conductors to protect them.