When type NM and NMC cable is run through a floor it must be protected by at least?
If the NM cable is installed where it passes through a floor, the cable must be protected for at least 6 inches above the floor by enclosing it in rigid metal conduit, intermediate metal conduit, or one of the other methods previously mentioned.
In which locations is type NM cable not allowed to be run?
Type NM cable cannot be run outdoors even if it is run in a raceway because this is considered to be a wet location. Type NM cable cannot be run in any raceway other than using it as a sleeve in accordance with 334.15(B) and 300.15(C) or in accordance with 334.12(A)(1) Exception.
What determines the ampacity of a wire?
The ampacity of the wire is determined by the amount of current in the wire at the point in which the conductor’s temperature rises 30°C. The ampacity rating of higher temperature rated wires is greater than lower temperature rated wires for any given size of conductor.
What is the maximum number of type NM cables that can be inserted into a connector?
Cable clamps or cable connectors must be used with only one cable, unless that clamp or fitting is identified for more than one cable. Some Type NM cable clamps are listed for two Type NM cables within a single fitting (UL White Book, product category PXJV).
How far from a luminaire does type NM cable need to be supported?
in length from the last point of cable support to the point of connection to a luminaire or other equipment, and (3) when not more than 3 ft. from the last point of support where flexibility is necessary for equipment that requires movement after installation. NM cable must be supported and secured every 4 ½ ft.
What material has best ampacity?
26 Cards in this Set
|Conductor sizes Up Grill 4/0 AWG are expressed in American wire gauge. Conductor sizes larger than 4/0 AWG are expressed in _____?||Kcmil|
|For a given conductor size , which material has the greatest ampacity?||Copper|
What is the largest size Romex?
No, there are two sizes larger than Romex® 6/3 which are a 4 AWG and a 2 AWG that come in a three conductor version only. Each of the 3 different sizes has 3 THHN electrical wires with insulation and one bare copper ground wire without insulation. All 3 versions come with a black outer jacket.
What is the difference between amperage and ampacity?
is that amperage is the electric current’s strength carried by a conductor or machine generated as measured in amperes while ampacity is the root mean square of the electrical current which a device (usually a wire) can carry within a specific environment (including temperature rating, power loss, heat dissipation, etc …
Can you put two Romex in connector?
The romex connector that is used has on the package the specs for wire size and number combinations. Usually more than two in any given connector is unacceptable.
Are two NM Cables allowed to be supported under 1 staple?
You are allowed to put 2 lines under 1 staple. The conductors can cross the gas line or run next to it but not secured to the gas line.
How is the ampacity of a NMC cable determined?
The 90°C (194°F) rating shall be permitted to be used for ampacity adjustment and correction calculations, provided the final derated ampacity does not exceed that of a 60°C (140°F) rated conductor. The ampacity of Types NM, NMC, and NMS cable installed in cable tray shall be determined in accordance with 392.80 (A).
Can a NM cable be used in a storage building?
Where it was in the 2011 NEC created a completely different interpretation of how type NM cable could be used. A literal interpretation of the old code language would allow a type NM cable to be used in any residential storage building, with no restrictions on what’s being stored in the building or what the building was being used for.
Can a NM cable be installed in a wet location?
Section 334.12 (B) does not allow type NM cable to be installed in wet locations or where exposed to corrosives such as chlorine but without the revised code language, sections 334.10 and 334.12 (B) were in conflict with one another.
What’s the difference between nm-b and THHN copper wires?
Up through 10ga all the copper wires have the same rating but then they start to diverge. I am particularly surprised that there is a different between NM-B cable and THHN wires… don’t NM-B cables use THHN wires as the individual conductors?