Conduit size
- Thread starter nizak
- Start date
- Status
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
But you would have room for more at a larger size due to needed adjustments.
- Location
- Massachusetts
Today I learned larger conduits have more room.
That alone makes your visit here worthwhile
- Location
- Simi Valley, CA
And your day complete.Today I learned larger conduits have more room.
RichB
Senior Member
- Location
- Tacoma, Wa
- Occupation
- Electrician/Electrical Inspector
Larn'in has token place--you kin leave fer t'day:lol:
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Right, how many more circuits you can run is not as simple as it may seem though.Today I learned larger conduits have more room.
DrSparks
The Everlasting Know-it-all!
- Location
- Madison, WI, USA
- Occupation
- Master Electrician and General Contractor
Nine #12 CCCs on a 20A OCPD in any size pipe would be in violation of NEC. #12 Cu has ampacity of 25A [NEC310.15(B)(16)]. 310.15(B)(2)(a) calls for 70% derating for 7 through 9 CCCs, which leaves you with 17.5 amps.
EDIT: This is assuming you are using the 75 degree column.
- Occupation
- Licensed Electrician
In the late 20th century era on into the early 21st the magic number is Nine CCCs for fifteen or twenty amp circuits. Works out for single phase and three phase. I don't know if that was planned or serendipitous.
DrSparks
The Everlasting Know-it-all!
- Location
- Madison, WI, USA
- Occupation
- Master Electrician and General Contractor
Oh, I wasn't familiar with the magic number table in the NEC :lol:
- Occupation
- Licensed Electrician
Not old enough to be a Beatles fan I guess.
The magic number works, although 210.4(B) is making it harder to get as many circuits in a 1/2" pipe as we used to and moving up to 3/4 doesn't help much. Who wants to bend 1" all day? I don't. Let's go buy some rolls of MC. While we're at it let's go get some guys that don't need to know anything about electrical to drag it around.
- Location
- Massachusetts
But why would you use the 75 degree column?
For the purposes of derating, unless we are using some odd wire, we can use the 90 degree column.
That means 9 CCCs 12 AWGs in a conduit can still use 20 amp OCP.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
110.14 is for terminations though, the conductors are still able to be adjusted from their 90 deg values (unless they are indeed 75 deg conductors). Final size of conductor selected however can not be smaller then whatever size the 60 or 75 degree terminals call for.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Are we on the same page? I expect someone like you already knows this but maybe we are not talking about the same thing here causing some confusion.
It is not exactly stated in one simple sentence in one code section.
310.15 applies to the conductors - we make adjustments from 90 degree values if we have 90 degree insulation.
However after making adjustments we still must have a conductor no smaller then what is called for in the 60 or 75 degree columns of ampacity table for the sake of termination temperatures. That gets us back to what was mentioned about 110.14 Two different ampacities are required for same conductor in different portions of the conductor - the higher ampacity is what must be used, but don't know of any possible adjustments to termination ampacity, just to conductor ampacity only as it applies to it's insulation.
You can have a situation where ampacity adjustment says you can have a 6 AWG conductor for the temp rating of the insulation, but same application may need 4 AWG for the termination temperature - so in that case you still must use the 4 AWG.
Yes it is, read 110.14(C)
Which is what 110.14(C) is saying
Yes it does.
I was just wondering what the point was to post #15
Roger
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Ok, 110.14 doesn't tell you how to make ampacity adjustments just that you can make them to the conductor. There is no adjusting the terminal, you will always have a conductor with a minimum size no smaller then the termination calls for, you can adjust the conductor ampacity as it applies to it's insulation, so you are starting (which that word start is what triggered my first reply) with the 90 degree column in the ampacity table as it relates to insulation not to the terminal that is likely only 60 or 75 degrees.
sorry for any confusion.
- Location
- Massachusetts
I am more confused now than before.:huh:
- Status