Paperman
Well-known member
Can anyone tell me or better yet show me how to find the number of #12 conductors in can have in a 1" EMT. 100' run with a mix of 15A & 20A. I would love to add a 50A 240 in there if possible. Teach me how to fish!!!
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How many conductors in 1" EMT
- Thread starter Paperman
- Start date
matt_i
Well-known member
In 1" EMT the conduit fill tables show a max of 26pc #12 awg. Are you close to that already?
matt_i
Well-known member
A primer is here
https://www.belden.com/resourcecent...uit-Capacity-Chart-Conduit_Capacity_Chart.pdf
But I think its confusing.
An easier way is to sum the areas of the individual cables' ODs. Use (pi)/4* OD^2. (They use a multiplier factor of .7854 in the pdf so they don't have to talk about pi/4.)
Get the ID of the conduit.
Calculate the total internal area of the conduit = pi/4 * ID^2.
The max fill (sum of all cables) can be 40% of the total internal area.
Look here for OD references, i'm using stranded
http://www.usawire-cable.com/pdfs/thhn_thwn.pdf
So for 10pc #12....10 * pi/4 * (.130)^2 = .1327 sq inches
for 2pc #6....2 * pi/4 * (.256)^2 = .1029 sq inches
Sum of conductors is 0.2356 sq inches
EMT specs
https://steeltubeinstitute.org/steel-conduit/types-of-steel-conduit/electrical-metallic-tubing-emt/
1" has an OD of 1.163" and a wall thickness of 0.057, for an ID of = 1.049"
pi/4 * (1.049)^2 = 0.8642 sq inches * (0.4 or 40%) = 0.3456 sq in available for use.
So...0.2356 (wire area) is less than 0.3456 (available area @ 40% fill)
You should be good to go.
https://www.belden.com/resourcecent...uit-Capacity-Chart-Conduit_Capacity_Chart.pdf
But I think its confusing.
An easier way is to sum the areas of the individual cables' ODs. Use (pi)/4* OD^2. (They use a multiplier factor of .7854 in the pdf so they don't have to talk about pi/4.)
Get the ID of the conduit.
Calculate the total internal area of the conduit = pi/4 * ID^2.
The max fill (sum of all cables) can be 40% of the total internal area.
Look here for OD references, i'm using stranded
http://www.usawire-cable.com/pdfs/thhn_thwn.pdf
So for 10pc #12....10 * pi/4 * (.130)^2 = .1327 sq inches
for 2pc #6....2 * pi/4 * (.256)^2 = .1029 sq inches
Sum of conductors is 0.2356 sq inches
EMT specs
https://steeltubeinstitute.org/steel-conduit/types-of-steel-conduit/electrical-metallic-tubing-emt/
1" has an OD of 1.163" and a wall thickness of 0.057, for an ID of = 1.049"
pi/4 * (1.049)^2 = 0.8642 sq inches * (0.4 or 40%) = 0.3456 sq in available for use.
So...0.2356 (wire area) is less than 0.3456 (available area @ 40% fill)
You should be good to go.
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wyliesdiesels
Well-known member
Havent pulled a wire yet, I would be way under that. Planning my runs well ahead of hanging steel. I would like to pull in 8-10 #12 and then also a pair of #6 for a 50A outlet primarily for welder usage. Id love to know how to do the calculations for mixed size.
As said by moto above, you will need to derate ampacity because of number of conductors.
This will create an issue for you because 10-20 conductors requires 50% derating.
[table 310.15(B)(3)(a)]
#12 THWN has a 90* c ampacity of 30a x 50% = 15a
#6 THWN has a 90* c ampacity of 75a x 50% = 37.5 (use next standard size breaker of 40a).
What kind of welder will you be running? If it needs 50a, you will need to run the welder circuit in separate pipe.
And if you want 20a circuits with the #12, you will either need to reduce to 8 wires or use #10 for 10 wires which may throw off the pipe fill....
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At maximum draw it is 42A. This is 250A @ 40% Duty Cycle. I can breaker down to 40 and deal with nuisance trips and move the machine if needed.
I can live with 4 circuits, it just puts more outlets on the same feeder. I was looking at a few dedicated runs but its not a need, just a want.
I can live with 4 circuits, it just puts more outlets on the same feeder. I was looking at a few dedicated runs but its not a need, just a want.
sberry
Banned
There is a difference between number of wires and number of current carrying conductors too.
You can "park" a lot of wire doing this. Been there and done it. The code doesn't distinguish between "might do and want". What I mean by that is if these are convenience outlets they may never be loaded or are not all loaded like an operating machine. While a wire for a light may have a 15 breaker there may only be an amp or 2 on it and not all circuits in the pipe will be busy or used at the same time. The welder only requires an 8 and possibly a 10 if it was a single circuit in pipe, if it's on 6 it's not contributing to a problem.
Where fill is a concern there is a possibility of 6 120v circuits with 9 wires. 240 takes 2 so could get 5 120 and 1 240 with no derate and possibly another 1 or 2 before it went over the limits. In a strict design matter it wouldn't be much a concern unless each actually had 20A and the welder was running wide open at limit. No matter,,, this is a 250 mig, do not use an undersize breaker. If this is for maintenance work it's not an issue anyway plus the 6 is better than it needs. The only way it heats up is if you were in trailer production or building stoves etc and this would be big wire special gas.
You can "park" a lot of wire doing this. Been there and done it. The code doesn't distinguish between "might do and want". What I mean by that is if these are convenience outlets they may never be loaded or are not all loaded like an operating machine. While a wire for a light may have a 15 breaker there may only be an amp or 2 on it and not all circuits in the pipe will be busy or used at the same time. The welder only requires an 8 and possibly a 10 if it was a single circuit in pipe, if it's on 6 it's not contributing to a problem.
Where fill is a concern there is a possibility of 6 120v circuits with 9 wires. 240 takes 2 so could get 5 120 and 1 240 with no derate and possibly another 1 or 2 before it went over the limits. In a strict design matter it wouldn't be much a concern unless each actually had 20A and the welder was running wide open at limit. No matter,,, this is a 250 mig, do not use an undersize breaker. If this is for maintenance work it's not an issue anyway plus the 6 is better than it needs. The only way it heats up is if you were in trailer production or building stoves etc and this would be big wire special gas.
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sberry
Banned
As a practical matter there is a place for inch pipe but I don't has it unless I have to. I would be tempted to run another pipe for a welder circuit. I don't want another layer and collection of fittings unless I had to. It's slightly different if you are in the wiring business but for diy its a pain.
Buy a box of adapters, couplings and a bundle of pipe as well as common boxes and a couple deep for welder recepts. This is stuff to have left over so you don't have to run to the store every time you want to add a fitting. No point in having a pile of odd stuff left you never use.
How far is the welder circuit? The heaviest mig, a 252 thay comes factory cord calls for 8, some of them only need 10, I got a couple convenience with 10 in 1/2 pipe. I do have a couple 6, one is the home for a 250 and another where I had the wire anyway but most of my welding is from 10 wire circuits.
You have a big building, just up and down walls can add 40 ft, a size larger wire wont hurt. I have 5 additional panels besides the main, basically 1 on each wall and another for air comps. I did it before the pour but,,, adding a panel with some 2 alum wire can same a ton of work and piping, hook a welder recept from it and all the branch circuits don't have to run all the way across. Saves big on V drop on 120V as well. Most all the 120 is just a few ft from a panel. I don't have any inch in the whole place and only ran 1 extra 3/4 for welder about 10 ft. Had I used 10 wire could have eliminated that too.
I see this is 100 ft run, if its all going in a general area would certainly consider another panel, an 8 space is only 30$ but wouldn't have to have a gob of wires and would improve performance a little.
Buy a box of adapters, couplings and a bundle of pipe as well as common boxes and a couple deep for welder recepts. This is stuff to have left over so you don't have to run to the store every time you want to add a fitting. No point in having a pile of odd stuff left you never use.
How far is the welder circuit? The heaviest mig, a 252 thay comes factory cord calls for 8, some of them only need 10, I got a couple convenience with 10 in 1/2 pipe. I do have a couple 6, one is the home for a 250 and another where I had the wire anyway but most of my welding is from 10 wire circuits.
You have a big building, just up and down walls can add 40 ft, a size larger wire wont hurt. I have 5 additional panels besides the main, basically 1 on each wall and another for air comps. I did it before the pour but,,, adding a panel with some 2 alum wire can same a ton of work and piping, hook a welder recept from it and all the branch circuits don't have to run all the way across. Saves big on V drop on 120V as well. Most all the 120 is just a few ft from a panel. I don't have any inch in the whole place and only ran 1 extra 3/4 for welder about 10 ft. Had I used 10 wire could have eliminated that too.
I see this is 100 ft run, if its all going in a general area would certainly consider another panel, an 8 space is only 30$ but wouldn't have to have a gob of wires and would improve performance a little.
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All point well taken and have been thought of. This is a 80x120 building, 480D main service. It was steel tube and wire manufacturer in from the mid 50's through about 1980. All of the 480 is gone save a small GE lighting transformer A new 15KVA 480/240 transformer mounted mid building feeds a small distribution panel under it. From there that panel feeds 3 others in corners of the shop. These final outer panels feed all the 240/120 needs in their respective area. Most of this is new install as all that was in place for the last 30 years was lighting and a few scattered outlets along with about 15 fire hazards of scattered scabbed lights and receps. The 1-EMT is salvaged from a long gone 480 run. The actual run in question is about 80', 10 up 60 over and 10 down. All my big stuff is 480, lathe, mill, drill, air comp., grinder etc. So I hope this clears a bit of what the shop is and what I am doing. I need to run a 250 mig, 180 tig, waste oil furnace or a 2 post lift. That's the extent of the big loads I PLAN to have. Might have parts washer with a fairly healthy heater but that is going into a different section of the building. Lots to do and not much time before I see snow!!
I appreciate the help from all yall.
I appreciate the help from all yall.
sberry
Banned
Yes, I understand salvaged pipe.
wyliesdiesels
Well-known member
All point well taken and have been thought of. This is a 80x120 building, 480D main service. It was steel tube and wire manufacturer in from the mid 50's through about 1980. All of the 480 is gone save a small GE lighting transformer A new 15KVA 480/240 transformer mounted mid building feeds a small distribution panel under it. From there that panel feeds 3 others in corners of the shop. These final outer panels feed all the 240/120 needs in their respective area. Most of this is new install as all that was in place for the last 30 years was lighting and a few scattered outlets along with about 15 fire hazards of scattered scabbed lights and receps. The 1-EMT is salvaged from a long gone 480 run. The actual run in question is about 80', 10 up 60 over and 10 down. All my big stuff is 480, lathe, mill, drill, air comp., grinder etc. So I hope this clears a bit of what the shop is and what I am doing. I need to run a 250 mig, 180 tig, waste oil furnace or a 2 post lift. That's the extent of the big loads I PLAN to have. Might have parts washer with a fairly healthy heater but that is going into a different section of the building. Lots to do and not much time before I see snow!!
I appreciate the help from all yall.
Hell, if youve got 480v, why not run 480v welders?
They are a lot nicer than their 240v duty cycle rated counterparts... Ive used both...
And I assume the 15KVA is single phase transformer. If so, youve only got about 70a @ 240v single phase.
If you run a 480v welder, you can maximize the limited 240v single phase capacity you have.
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wyliesdiesels
Well-known member
I have both already. My Miller Mig is about 20 years old and the Tig is about 10. Both have served me well and will keep doing what they do a long time I hope. One big 480 stick machine for the heavy work. Idealarc 300, not light but it is smooth!!
o ok welders are 480v?
I missed that somehow though it wasnt in your 480 list of equipment...
sberry
Banned
I think his small welders are single phase. Unless this is production moist of the difference is moot. But I do have a question and maybe Wylie knows as I don't really know squat about trannys but the poco on my pole is 15K to a 400 service. The math doesn't seem right and I certainly don't load it but how do they come to this conclusion? I wondered when thy8 did it and the lineman said if it was an issue they would change it out to 25 but it works flawless and even with stuff going as much as it can be and my big tig it doesn't blink.
Back in the day could see my comp flutter an incandescent lamp but this is pretty solid, its small at 3 hp but cant see it start.
Back in the day could see my comp flutter an incandescent lamp but this is pretty solid, its small at 3 hp but cant see it start.
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