Service wire size

Status
Not open for further replies.
T

Therealcrt

Member
Location
Kansas City
Occupation
Electrician
1200a main 120/208 single phase, pulling in aluminum wire . What size wire would that be, how many sets per phase and conduit size
 
Therealcrt said:
1200a main 120/208 single phase, pulling in aluminum wire . What size wire would that be, how many sets per phase and conduit size
Click to expand...
Hint article 310.

This sounds like a study question so tell us what you come up with and how you came up with it then we can critique it.
 
Therealcrt said:
1200a main 120/208 single phase, pulling in aluminum wire . What size wire would that be, how many sets per phase and conduit size
Click to expand...
That is a three phase system voltage, I can't imagine any utility giving you a 3-wire service at 1200 amps from a three phase 208Y/120 volt system.
 
Take 1200 amps and divide the number of sets you will run. Take that number over the Article 310 as Roger mentioned. (Hint I would run 4 sets).
 
Therealcrt said:
What do you even mean? L1 L2 N

Single phase 2 hots and a neutral. Neutral is a current carrying conductor
Click to expand...
While the neutral will be carrying current, it is not a current carrying conductor for the purposes of ampacity adjustment. 310.15(B)(5)(a)
 
Therealcrt said:
What do you even mean? L1 L2 N

Single phase 2 hots and a neutral. Neutral is a current carrying conductor
Click to expand...
As Don stated the neutral will not be considered a CCC since it only carries the imbalance between the two hot conductors. This may help:

Neutral Conductors:

Here's some examples of when to count and not count the neutral as a current carrying conductor or CCC:

3Ø- 208Y/120 or 480Y/277 volt system-different circuit types:
A) 2 wire circuit w/ 1 ungrounded, 1 neutral = 2 CCC's
B) 3 wire circuit w/ 2 ungrounded, 1 neutral = 3 CCC's
C) 4 wire circuit w/ 3 ungrounded, 1 neutral = 3 CCC's*

Notes:
A) A normal 2 wire circuit has equal current flowing in each of the circuit conductors so they both count as CCC's.
B) In this circuit the neutral current will be nearly equal to the current in the ungrounded conductors so the neutral counts as a CCC
C) In this circuit the neutral will only carry the imbalance of the current between the three ungrounded conductors so it is not counted as a CCC, with an exception, *if the current is more than 50% nonlinear (see below for NEC article 100 definition) then the neutral would count as a CCC.

1Ø- 120/240 volt system-different circuit types:
D) 2 wire circuit w/ 1 ungrounded, 1 neutral = 2 CCC's
E) 3 wire circuit w/ 2 ungrounded, 1 neutral = 2 CCC's

Notes:
D) A normal 2 wire circuit has equal current flowing in each of the circuit conductors so they both count as CCC's.
E) In this circuit the neutral will only carry the imbalance between the two ungrounded conductors so the neutral is not counted as a CCC.

Nonlinear Load. A load where the wave shape of the steady-state current does not follow the wave shape of the applied voltage.

Informational Note: Electronic equipment, electronic/electric-discharge lighting, adjustable-speed drive systems, and similar equipment may be nonlinear loads.
Click to expand...
 
Status
Not open for further replies.
Top