Mike Honcho
Well-known member
whats the biggest circuit i can run through one inch pvc approx 40ft? thanks in advance.
chris
chris
largest circuit
- Thread starter Mike Honcho
- Start date
Speedy Petey
Well-known member
That is a loaded question.
What are you doing that you are asking this?
What are you doing that you are asking this?
Speedy Petey
Well-known member
Look at a conduit fill chart and see if what you want to do fits the fill limits.
OP
Mike Honcho
Well-known member
sorry, subpanel
rockwithjason
Well-known member
well, you can fit 4 8awg's in there, that would give you 40a depending on the conditions
pattenp
Well-known member
1 inch sch40 PCV conduit can take four #4 Cu THWN-2 which is rated at 85 amps at 75 degrees C. Other wire types will be less, such as RHH/RHW is four #8 Cu which is 50 amps @ 75 deg C.
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OP
Mike Honcho
Well-known member
thanks patten, i assume that sch 80 will cut that down some? i was looking to run 60 amp with it. it was already there when i bought the house. if not ill use it for something else.
Highbeam
Well-known member
I just pulled 70 feet of wire through 1" conduit this weekend. It was only 2-#8 and 1-#10 (all THHN-THWN-THWN2 multi rated as I recall) and it went okay but the 4-90 degree bends made lube necessary. In a "dry" location it would appear that the #8 is rated for 55 amps which you can round up to 60. Of course you'll need 3-#8s and a 10 guage.
Just because you can does not mean it will be easy.
Just because you can does not mean it will be easy.
pattenp
Well-known member
For 60A use THHN/THWN-2, three #6 Cu and one #10 Cu for the equipment ground. That will fit nicely in sch80 PVC.
#8 THHN/THWN is not 55A, it's 50A @ 75 deg. C.
#8 THHN/THWN is not 55A, it's 50A @ 75 deg. C.
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rockwithjason
Well-known member
yup your right, i goof brained and read the wrong column
Highbeam
Well-known member
That's not what the big chart at the home depot said. It called out 55 amps but I still breakered it at 50.
Speedy Petey
Well-known member
Who you gonna believe, a HD chart, or pattenp??
I'll give you a hint: He's NOT orange.
Aceman
Well-known member
You realize the big chart at Home Depot isn't the NEC, right?
pattenp
Well-known member
OP
Mike Honcho
Well-known member
Awesome, thanks for all the help guys, happy i dont have to dig another trench
Highbeam
Well-known member
Just brought up the HD chart since it was there and a surprising amount of work gets installed based on that chart. So are you saying the chart is wrong?
I stuck to 50 amps on 8 gauge thwn-2, which jives with pattenp's advice. Pattenp has been very helpful to me and others on this forum and I never said he was wrong.
I stuck to 50 amps on 8 gauge thwn-2, which jives with pattenp's advice. Pattenp has been very helpful to me and others on this forum and I never said he was wrong.
pattenp
Well-known member
I never took it as being said I was wrong. I try my best to give correct information, but being human I do get things wrong at times. It's always good to question information and to do some research to make sure the info you are receiving is consistent.
I need to take a look at that HD chart.
I need to take a look at that HD chart.
pattenp
Well-known member
Just went to HD and their chart does show what the NEC table has for #8 THHN which is 55 amps @ 90 degrees C. The catch is even though technically THHN is a dry location rating and is listed in the 90 degree C column the terminal connections on devices such as breakers are only rated at 75 degrees C, so you need to size the conductor by 75 degrees C. I think it's misleading to the unknowing DYI'er who looks at that chart and may think it's okay to use THHN at the amps for 90 degree C. I also stopped at Lowes and checked their chart and it only list the 60C or 75C amp ratings for the different wire. So the #8 THHN is shown as 75C for 50 amps.
Highbeam
Well-known member
Thanks Pattenp, I didn't mean to make you go running all over town but I do appreciate the information.
wyliesdiesels
Well-known member
Sounds like HD needs to fix their charts!!
I run into this issue at work all the time with contractors. I dont even know why they list 90 deg c if all of the termination points are always rated at 75 degrees.
Can be very miss leading. You'd be surprised at the amount of electrician's that i have to explain this too. I have been in the business for 4 years while some them have been doing this for 20 plus years.
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Aceman
Well-known member
The 90 degree column is usually used for derating purposes.
pattenp
Well-known member
Oh don't worry, I didn't make the trip for you. I had to go to Lowes and HD today anyway.
That is a great point. When you have more than 3 current carrying conductors in a single conduit and you need to de-rate it. I believe thats the rule but not a 100 percent sure. I have only run into that on a few occasions.
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wyliesdiesels
Well-known member
It is amazing how many LICENSED contractors are out there who dont really know what theyre doing. My boss(30 yr union electrician) at the last company i worked at thought that different brands of breakers were interchangeable with different brands of panels if the breakers fit the panel. I told him that would violate the U/L listing and its against code(had my code book in hand and was going to point out the code section) and he said 'no, its fine, if the breakers fit then theres no issue.' He was always giving me brands of breakers that didnt match the panel but I always made sure to match the correct breakers with the correct panel because i didnt want any issues down the road!
Hahah i hear you on that. I think when ul test it, they test the panel as whole with their breakers.
The best is when i find contractors installing stuff that doesn't match what the approved shop drawings call for. So many times i find that they use the cheap chinese dimmer switches that are not ul listed even though the shop drawing they submit clearly states levtion/lutron/hubble etc. Never mind that the switches are will almost burn your hand when you you go to turn off the switch lol.
That's some scary ineptitude and a lawsuit in the future!