Why would one care about conductor sizes?
Because smaller conductors have a higher resistance which, when current passes through them, a large heat is developed. By "sizing up" we reduced the heat lost (line loss).
What table is referenced when determining a flexible cord for certain conditions of use?
Conductors get hotter, when installed next to other conductors. If installing more than 3 conductors in a raceway, what tables should be referenced to adequately determine ampacity?
Table 5c and
- Table 2 for copper
- Table 4 for aluminum
What are the default conductor termination temperatures for equipment?
- 60 degrees for current of 100 amperes or less and when using #1 awg or smaller wires.
- 75 degrees for current of more than 100 amperes and when using greater than #1 awg wires.
What are tables 1 and 3 used for?
Ampacities of single conductors in free air.
- Table 1 is for copper
- Table 3 is for aluminum.
The ampacities of flexible cord is determined from...?
Table 12 (Close attention should be paid to the number of wires in the cord, correction factors still apply).
When determining ampacities of conductors in single phase 3 wire systems, how many wires are counted for each three wire circuit?
2! The neutral wire is not counted. (When determining box fill and conduit fill, be sure to count the neutral)
When can a neutral conductor be bare?
Otherwise what kind of identification is required?
In a consumer's overhead service.
- A white or grey insulation up to and including #2 awg (after this, phase tape or other suitable marking at every accessible end of the conductor is acceptable)
- A longitudinal ridge along the conductor
If installing a switched light in conduit, could one splice a white wire to be switched (so that a black wire can return to the load)?
No, this method is only acceptable when using manufactured cables.
What three colours of wires are used in a single phase 3 wire system?
Black Red White
In general should a 20 amp breaker ever be used in a #14 awg circuit.
No, see rule 14-104
What is the minimum size of conductors allowed in flexible cords?
#18 awg, with a few exceptions.
- Tinsel cord can be #27 awg
- Cords for specific devices can be #20 awg
When used as luminaire lighting, equipment wire will not be smaller than...?
#18 awg copper