wire in conduit

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mannyb

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we have a current project with drawings but drawings arent that detailed. pnly really requirements are that conduits are to be 3/4 an lenghts over 50' of 20a circuits require #10 wire. its goint to be in a drop ceiling but the electrical sits in a weird area and running conduit will be a challenge. Our idea is to run less conduits with more circuits in conduit. if we run 8 ckts which is 4 hots 4 neutrals and 1 ground. #10 wire 1'' conduit using 70% derating? first would that comply with NEC and 2nd Would running 10 ckts 5H/5N/1G and use 50% would we still comply NEC. 3rd when I run #10 but rough in walls would i need to use #10/2 MC for plugs/lighting circuits?? If so can you provide NEC 2014 page
 
mannyb said:
we have a current project with drawings but drawings arent that detailed. pnly really requirements are that conduits are to be 3/4 an lenghts over 50' of 20a circuits require #10 wire. its goint to be in a drop ceiling but the electrical sits in a weird area and running conduit will be a challenge. Our idea is to run less conduits with more circuits in conduit. if we run 8 ckts which is 4 hots 4 neutrals and 1 ground. #10 wire 1'' conduit using 70% derating? first would that comply with NEC and 2nd Would running 10 ckts 5H/5N/1G and use 50% would we still comply NEC. 3rd when I run #10 but rough in walls would i need to use #10/2 MC for plugs/lighting circuits?? If so can you provide NEC 2014 page
Click to expand...

8 circuits would be 8 hots 8 neutrals, not 4 and 4. Yes, 8 CCC requires 70% derating, which limits you to 25A OCP on #10. You can run 10 CCC, conduit size permitting. Derating 50% of #10 @ 90c (40A) gives you 20A, so you're still ok.
 
If you have 20 amp circuits you can run 10-2 wire circuits in one conduit with #10 AWG conductors and still be good for 20 amps. 20 CCC's = 40 amps * 50% = 20 amps.
 
infinity said:
If you have 20 amp circuits you can run 10-2 wire circuits in one conduit with #10 AWG conductors and still be good for 20 amps. 20 CCC's = 40 amps * 50% = 20 amps.
Click to expand...


In areas where we run 20a w #10 AWG Homeruns would 12/2 be acceptable if we roughed in walls and light fixtures with 12/2 MC and still meet all requirements
 
jumper said:
Yes. The #12 MC does not have to be derated also.

The #10s in the conduit and the #12s in the MC would both be good for 20A.
Click to expand...


Thanks for reply. isnt there a noted somewhere in Nec that the wire has to be the same color throughout entire lenght?
 
mannyb said:
Thanks for reply. isnt there a noted somewhere in Nec that the wire has to be the same color throughout entire lenght?
Click to expand...

Only if there are two different voltages in the building, such as 408/277 and 208/120. Note the bold.

210.5(C)(1)
(1) Branch Circuits Supplied from More Than One
Nominal Voltage System.
Where the premises wiring sys-
tem has branch circuits supplied from more than one nomi-
nal voltage system, each ungrounded conductor of a branch
circuit shall be identified by phase or line and system at all
termination, connection, and splice points in compliance
with 210.5(C)(1)(a) and (b).

(a)
Means of Identification.
The means of identification
shall be permitted to be by separate color coding, marking
tape, tagging, or other approved means.

(b)
Posting of Identification Means.
The method uti-
lized for conductors originating within each branch-circuit
panelboard or similar branch-circuit distribution equipment
shall be documented in a manner that is readily available or
shall be permanently posted at each branch-circuit panel-
board or similar branch-circuit distribution equipment.
 
jumper said:
Only if there are two different voltages in the building, such as 408/277 and 208/120....
Click to expand...
But that is only if you use color as the means of identification.

And even if you do use color, with MC being multiconductor cable, it can be color-phase taped at both ends to maintain color identification. Only the green cannot be reidentified.
 
jumper said:
Only if there are two different voltages in the building, such as 408/277 and 208/120. Note the bold.
Click to expand...


I only mentioned because some mention that the wire had to be at least same color throughout wire length. if thats a concern I will just phase per Smart $ comment
 
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mannyb said:
The Print does show single pole 20a and the plan does show in electrical plan to run neutral for each circuit.
Click to expand...

That has become a pretty common standard with the requirement to use multipole CB's or handle ties.
 
What are connected loads?

15/20 amp general use receptacle outlets - you must use 15 or 20 amps (depending on OCPD) as the load when determining conductor ampacity.

Otherwise a fixed load of 14 amps on a 20 amp breaker is still a 14 amp load for ampacity calculations.
 
Just got done with a job where we used 8 circuits in a 1". Keep in mind you're allowed 16 wires, no ground. A 4/11 box only holds 16 #10 so if you have the pipe full and need to splice you'll have to use extension rings. Be careful making head and use plenty of lube, it was as hard a pulling 4/0 through a 2".
Also, maybe someone else can chime in, if you do run a ground I believe it has to be derated as well.
 
MiElectrician said:
Just got done with a job where we used 8 circuits in a 1". Keep in mind you're allowed 16 wires, no ground. A 4/11 box only holds 16 #10 so if you have the pipe full and need to splice you'll have to use extension rings. Be careful making head and use plenty of lube, it was as hard a pulling 4/0 through a 2".
Also, maybe someone else can chime in, if you do run a ground I believe it has to be derated as well.
Click to expand...
This is where semantics count :) If you run "a ground" per NEC definition I guess that means you are filling your conduit with soil:) (NEC: Ground= earth). If you are installing an equipment grounding conductor, that conductor would need to be taken into account as number of conductors allowed in the conduit, but would not be taken into account for derating. If you are installing a grounded conductor it might or might not be taken into account in derating.
Jumper (Derek) has a very nice explanation chart:

Here's some examples of when to count the neutral as a CCC:

208Y/120 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 one exception, *if the current is more than 50% nonlinear then the neutral would count as a CCC.

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.

Giving credit where credit is due as it took a lot of work. The chart is actually Rob's (infinity)..
 
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augie47 said:
This is where semantics count :) If you run "a ground" per NEC definition I guess that means you are filling your conduit with soil:) (NEC: Ground= earth). If you are installing an equipment grounding conductor, that conductor would need to be taken into account as number of conductors allowed in the conduit, but would not be taken into account for derating. If you are installing a grounded conductor it might or might not be taken into account in derating.
Jumper (Derek) has a very nice explanation chart:

Here's some examples of when to count the neutral as a CCC:

208Y/120 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 one exception, *if the current is more than 50% nonlinear then the neutral would count as a CCC.

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.
Click to expand...
But if you ran 10 AWG conductors for 20 amp circuits because you needed to adjust ampacity - you also need to adjust the EGC proportionally per250.122 (B) and would need 10 AWG EGC.
 
MiElectrician said:
Just got done with a job where we used 8 circuits in a 1". Keep in mind you're allowed 16 wires, no ground. A 4/11 box only holds 16 #10 so if you have the pipe full and need to splice you'll have to use extension rings. Be careful making head and use plenty of lube, it was as hard a pulling 4/0 through a 2".
Also, maybe someone else can chime in, if you do run a ground I believe it has to be derated as well.
Click to expand...
If you have the pipe full and need to splice in that situation, I suggest at least a 6x6x4 box - though that would still probably be a little crowded as well - so probably an 8x8x4 minimum box. If you pulled solid conductor - it will pull hard. Stranded conductor will pull much easier, I pull all stranded conductors in general, but especially try to avoid 10 AWG solid. 12 and 14 solid can have advantages at times but stranded still pulls easier in general.
 
A 6X6X4 would allow 57-#10 conductors.
Why anyone would pull #10 solid in a raceway is beyond me. :slaphead:

If someone specifies #10 solid conductors they have no practical knowledge of how things are installed. I'll stop short of calling them dopes. :eek:hmy:
 
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