Toros
Senior Member
- Location
- Tujunga, CA
Hi,
what size EMT for (4) 3/0 THHN, + 1/0 EQG, Cu ????
thank you
what size EMT for (4) 3/0 THHN, + 1/0 EQG, Cu ????
thank you
conduit fill
- Thread starter Toros
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LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I know, I know! Pick me, pick me! 
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Use Tables 4 and 5 in Chapter 9
Chapter 5 gives you the area of the conductors-- so 3/0 THHN is .2679 sq. in. Now multiply by how many conductors you have and then do the same for 1/0.
Now add them together and go to Table 4 -- the first table is for EMT and look under the col. for more than 2 wires and find a conduit size that is at least as large as your calculation
Chapter 5 gives you the area of the conductors-- so 3/0 THHN is .2679 sq. in. Now multiply by how many conductors you have and then do the same for 1/0.
Now add them together and go to Table 4 -- the first table is for EMT and look under the col. for more than 2 wires and find a conduit size that is at least as large as your calculation
texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
Yep, I think 1" would be better.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Or any EGC, for that matter.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
10 inch
- Location
- New Jersey
- Occupation
- Journeyman Electrician
You can skip the calculation by looking in Table C.1 in Annex C.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Another option, there is also this great thing called Google and the internet. Open your computing terminal, and type in "raceway fill calaculator" and I bet you a Reuben you will have multiple choices.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
annex C is only if all the conductors are the same size
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Since you mentioned it first, I like this one: http://www.electrician2.com/rveltrain05/rf_calculator.html
You can still use annex C in this particular case - just look at how many 3/0’s fit in a certain size.
the 1/0 could be for medical equipment or other equipment that asks for a larger than normal ground. Or maybe it’s 3/0 wire on something like a 20A breaker and everything is upsized for voltage drop.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Sure you can do that sometimes but in some cases that wont work and you aren't guaranteed the smallest conduit. Imo, it is best to calculate when there are different sizes--
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
If it is a 20 amp circuit upsized for VD, then the EGC would also need to be 3/0.
Where might one need a 1/0 EGC with 3/0 ungrounded conductors? How about with a feeder tap from an 800 amp feeder?
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