K8MHZ
Senior Member
- Occupation
- Electrician
Where do you get 3? Table C.1 shows that 9 #12 THHN conductors are allowed in 1/2 inch EMT.
half inch condit
- Thread starter steelerdude
- Start date
- Status
Where do you get 3? Table C.1 shows that 9 #12 THHN conductors are allowed in 1/2 inch EMT.
K8MHZ
Senior Member
- Occupation
- Electrician
Huh?????? ?
- Location
- Bremerton, Washington
The ampacity of a 12 AWG THHN is 30, but limited to 25 amps at 75 deg C. For motors it would not be unusual to see a 50 amp CB with 12 AWG.
Its a poor question
the origonal question was looking for the max. amperage for 1/2" conduit. Is the OP asking for wire size or OCPD?
What does length have to do with this or the price of peanut butter?
The fill is based on 31% that has been discussed already. See the notes to tables in chapter 9 and Annex C for more.Roger
K8MHZ
Senior Member
- Occupation
- Electrician
What does length have to do with this or the price of peanut butter?
Roger
Look at the chart at the bottom of this page:
http://www.electrician2.com/electa1/ground2.html
steelerdude
Member
- Location
- washington
kwired
Electron manager
- Location
- NE Nebraska
1/2 inch conduit is not normally intended to carry current except for situations allowing it to be used as an equipment grounding conductor. How many amps worth of conductors you can place within it ... usually this is not something calculated either. You would normally figure out what you have for load first, then figure out what you would need for conductors to supply it, then determine what size of conduit is needed to contain them. - But maybe I have not been doing it right for a long time now.
What does length have to do with this or the price of peanut butter?
Roger
If length is less than 24 inches it changes fill requirements.
i know right :?
had book had to see if table was ampacity of conduit :slaphead::ashamed:
:lol:
What leads you to believe I was talking about the tubing being used as an EGC, I was talking about conductors within the tubing.
If you want to know more about conduit and tubing used as EGC's go here
Roger
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- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I would not use annex C as it is full of inaccuracies. I am not even sure why it is there as it is not an NFPA document.
kwired
Electron manager
- Location
- NE Nebraska
outside of 14,12,&10 AWG in 1/2-3/4 and maybe 1 inch raceways...how often do you have all same size conductors in a raceway? your EGC is usually smaller and maybe the neutral is smaller sometimes. Besides I can calculate maximum fill faster with Ch9 than I can find right table in annex C Helps when you have area of 14-6AWG already memorized because you use them enough you don't need to look them up.
- Location
- Massachusetts
I am an NPIT* and I was taught details are important so I will point out that three conductors take up more 'space' than two conductors assuming all conductors are the same size.
Now before you go one about how three bundle better than two, I agree, but even when bundled nicely the total space used is greater ......... details ...... details ........
(*Nit Picker In Training :angel:
)
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- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The only thing I can think of is that in certain situations when 2 wires are installed there is dead space under where the 2 wires may lay on the bottom side by side. This would make the pulling area smaller but does not change the free space in the conduit.
K8MHZ
Senior Member
- Occupation
- Electrician
I am an NPIT* and I was taught details are important so I will point out that three conductors take up more 'space' than two conductors assuming all conductors are the same size.
Now before you go one about how three bundle better than two, I agree, but even when bundled nicely the total space used is greater ......... details ...... details ........
(*Nit Picker In Training :angel:
Geez.....do I have to draw a picture for you?
K8MHZ
Senior Member
- Occupation
- Electrician
Amount of extra area needed in tubing per number of conductors (for 100% fill):
1 conductor = 1 unit and can fit in a 1 unit tube. 0 units of extra area per conductor is needed.
2 conductors = 2 units but need a 3.14 unit tube. 0.57 units of extra area is needed per conductor.
3 conductors = 3 units and will fit in a 3.5325 unit tube. 0.1775 units of extra area is needed per conductor.
4 conductors = 4 units and will fit in a 4.71 unit tube. 0.1775 units of extra area is needed per conductor.
and so on, gradually decreasing from 0.1775 per unit as the number of conductors increase.
1 conductor = 1 unit and can fit in a 1 unit tube. 0 units of extra area per conductor is needed.
2 conductors = 2 units but need a 3.14 unit tube. 0.57 units of extra area is needed per conductor.
3 conductors = 3 units and will fit in a 3.5325 unit tube. 0.1775 units of extra area is needed per conductor.
4 conductors = 4 units and will fit in a 4.71 unit tube. 0.1775 units of extra area is needed per conductor.
and so on, gradually decreasing from 0.1775 per unit as the number of conductors increase.
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kwired
Electron manager
- Location
- NE Nebraska
Here is how fill works out
Each large circle is 1 inch diameter. Each one in top row has smaller circles with max 53, 31, or 40% fill inside.
The bottom one has three of the same size as the 2 @31% inside it.
Judge for yourself if three @ 40% is more than 2 @ 31%
Each large circle is 1 inch diameter. Each one in top row has smaller circles with max 53, 31, or 40% fill inside.
The bottom one has three of the same size as the 2 @31% inside it.
Judge for yourself if three @ 40% is more than 2 @ 31%
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
I am an NPIT* and I was taught details are important so I will point out that three conductors take up more 'space' than two conductors assuming all conductors are the same size.
Now before you go one about how three bundle better than two, I agree, but even when bundled nicely the total space used is greater ......... details ...... details ........
(*Nit Picker In Training :angel:
Glad you cleared that up! I was thinking "Natural Pain in the ^**!
Your fill is off. Look at the one small circle in large circle. You can fit about six more smaller circles around the existing one. The one circle is far from 53% of the larger. At 53%, the smaller circle should have a diameter 73% of the larger. What you have for diameter is more likely the radius.
- Location
- Massachusetts
- Status