calculating current carrying conductors

Status
Not open for further replies.

journeyman0217

Senior Member
Location
philadelphia,pa
when running 2 travel wires for a 3way switch, would both conductors be considered current carrying even though only one leg would actually carry current when the light fixture is on, for the purpose of calculating the number of current carrying conductors in a raceway?
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
when running 2 travel wires for a 3way switch, would both conductors be considered current carrying even though only one leg would actually carry current when the light fixture is on, for the purpose of calculating the number of current carrying conductors in a raceway?
The CCC calculation excludes double counting of wires that, by design, cannot both be carrying current at the same time.
This lets you count two travelers as one CCC for adjustment purposes.
 

Carultch

Senior Member
Location
Massachusetts
great thanks golddigger. i am in 310.15 and cant seem to reference that, do you know what article that is in?

Carefully read the title of Table 310.15(B)(3)(A) in the 2014 edition.

This is a change from 2011. In 2011, it said "current carrying conductors". In 2014, it was changed to "conductors" with a footnote that specifies the details. I'm paraphrasing from memory.
1. Spare conductors intended to carry current in the future shall be counted.
2. Only simultaneously energized conductors shall be counted at any time. This was specifically written to exclude counting traveller wires when the switching state only turns on 2 out of 3 of them, at any instant.
3. Equipment ground conductors shall not be counted
4. Whether or not to count the neutral, depends on circumstances and application of that neutral conductor. See 310.15(B)(4).
 

journeyman0217

Senior Member
Location
philadelphia,pa
Carefully read the title of Table 310.15(B)(3)(A) in the 2014 edition.

This is a change from 2011. In 2011, it said "current carrying conductors". In 2014, it was changed to "conductors" with a footnote that specifies the details. I'm paraphrasing from memory.
1. Spare conductors intended to carry current in the future shall be counted.
2. Conductors that cannot be simultaneously carrying current by design, shall only be counted
3. Equipment ground conductors shall not be counted
4. Whether or not to count the neutral, depends on circumstances and application of that neutral conductor. See 310.15(B)(4).

ah, the damn footnote! it says "the count shall not include conductors that are connected to electrical components but that cannot be simultaneously energized" bingo
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
ah, the damn footnote! it says "the count shall not include conductors that are connected to electrical components but that cannot be simultaneously energized" bingo

Which could be interpreted to mean that you do not even count the set once. Maybe the language will be tweaked eventually?
 
Status
Not open for further replies.
Top