What conduit size do I need to use for 100 amp?

[zbusdriver]

Hello all, new guy here! I have the skill-set to run wire, plugs, light switches, and lighting. Zero knowledge on wiring a sub-panel. I need to run new electrical service to a newly built detached garage. I decided on 100 amp service so that in the future I can add a car charger if needed. So far I have a 24” (only 18” required) deep trench from the back of my house to the garage (25'). An electrician said that I need to use 2” PVC Schedule 40 electrical grade conduit. I actually have sixty feet of 2” sked 40 conduit on hand. However, I went to Home Depot tonight to pick up a couple of 2” square elbows for each end of the conduit going into both the house and the garage. The problem is that the 2” square elbows are GIGANTIC and both will be located in prominent eyesore positions. Can I use 1.25” or 1.5” conduit, or is it code that I use larger conduit because of the 100 amp service? Thank you!

 

[7635tools]

1 1/4” is what I would use. 3 #3’s and a #8 will fit in a 1” but would be easier to pull through 1 1/4”.


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[njhoudini]

I believe it depends on what cable you use for the conduit fill.

https://www.vikingelectric.com/c/Bu...ogId=10251&page=SCH_40_80_PVC_Conduit_Fil_VES

Are you using THHN/THWN? Looks like you could put six 3 gauge copper wire in 1.25 inch conduit so it sounds fine to use 1.25" unless you are using aluminum, where the bends would probably require a much bigger conduit.

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[njhoudini]

I also believe the 40 vs 80 depends 9n the local code. In NJ, 80 is required for underground because it is thicker and less likely to break where it emerges from the ground. If your region also has cold temps, you may need expansion joints to allow for movement from the temperature swings.

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[exranger06]

Figure out which type/size wire you're going to use, THEN figure out how big the conduit needs to be to accommodate the wire.

 

[sberry]

2 alum will go down a straight 1 1/4, if it has turns it needs 1 1/2, gets tuff more than 2 but glides down 2.

 

[Norcal]

2 alum will go down a straight 1 1/4, if it has turns it needs 1 1/2, gets tuff more than 2 but glides down 2.

#2 AL is not rated for 100A.

 

[zbusdriver]

Thank you for your replies. I am behind schedule so I am trying to bury the conduit so my brick parer guys can get started. I'm not sure of the wire type, or size at this point. I'd be best served with the 2' but the flat elbows that would be on either end going into the house and into the garage are enormous (approximately 4' by 5" and several inches long).

 

[alfredeneuman]

To get the full 100Amps, you'll need #1Al with a #6Al ground, or #3Cu with a #8Cu ground.

I suggest you use 1-1/2" for your conduit. It really doesn't cost much than 1-1/4", but it will make for much easier pulling

 

[exranger06]

I fit three #3 copper wires and a #8 ground wire (good for 100 amps) in 1.5" conduit with no problem, but I only had to run it a very short distance. It would probably be ok for longer distance too though. How long is this conduit run?

 

[PCustoms]

What the heck is a flat elbow?

Use what you got for $0

 

[exranger06]

What the heck is a flat elbow?

Use what you got for $0

I assumed he was talking about an LB.

 

[dogdog]

1 1/4” is what I would use. 3 #3’s and a #8 will fit in a 1” but would be easier to pull through 1 1/4”.


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Also needed to consider the number of bends within a minimal distance...if you don't over size... I had to pull 7 #6 in 1.5" emt.. let's say the whole 140' was easy, the last 10' that had 3 90deg sweeps was just painful... maybe it was a 2" emt , anyways the point is... that... consider to over size it , if there are the number of sweeps in a close distance... especially if you plan to fill the conduit....

 

[n20junkie]

Don't go small. Conduit is cheap in comparison. 2” minimum.

Smaller is always great right up to the point you have 4 wires on the rope and they don’t want to pull through.

 

[sberry]

Ya,,, I was just mentioning sizing. I have pulled a lot of 2 in 1 1/2. Number 1 would be awfully tight if a guy had to turn it and he would be wishing for 2.
I was going to ask guys here,,, anyone see 90 breakers in the box stores? I scored a couple 70 on clearance a good while back but don't recall seeing any others between 60 and 100? Does everyone go to the jobber to get them?

 

[3rdgendslmech]

I pulled 130 feet of 3 #2AL and a #4Al back through 1½ 3 months ago. 2, 90 sweeps and a LB at the house and at the barn. It pulled pretty easy with a friend and wire lube. I'm only good for 90 amp service but I doubt I'll hit 60 anytime soon

 

[sberry]

You don't need much glide on a rag ahead of a pull and its not too bad in 1 1/2 because you can push and pull. Getting it back out if wanted is another matter, done it. Its all easy both ways in 2. In the smaller pipe as was mentioned you can really tell when it gets to the last couple bends. 2 ant too bad.

 

[dogdog]

I pulled 130 feet of 3 #2AL and a #4Al back through 1½ 3 months ago. 2, 90 sweeps and a LB at the house and at the barn. It pulled pretty easy with a friend and wire lube. I'm only good for 90 amp service but I doubt I'll hit 60 anytime soon

If those sweeps are close to each other, they get considerably harder to pull... or extremely hard, I hang my whole weight on the rope and still couldn't get it through, had to disassemble the who thing, fit it through one section at a time then re-assemble. .... no lube was going to help.. Yes I did stack the wires, lead wire longer then another shorter and tape and lube etc...

 

[sberry]

I put them on 60 too. Never tripped or had anyone trip one.

 

[mike93lx]

Ya,,, I was just mentioning sizing. I have pulled a lot of 2 in 1 1/2. Number 1 would be awfully tight if a guy had to turn it and he would be wishing for 2.
I was going to ask guys here,,, anyone see 90 breakers in the box stores? I scored a couple 70 on clearance a good while back but don't recall seeing any others between 60 and 100? Does everyone go to the jobber to get them?

Order online at home depot, it is at the store in a week. Not really a project that all of a sudden pops up, so it wouldn't matter much to me if they had it in stock or not

 

[3rdgendslmech]

If those sweeps are close to each other, they get considerably harder to pull... or extremely hard, I hang my whole weight on the rope and still couldn't get it through, had to disassemble the who thing, fit it through one section at a time then re-assemble. .... no lube was going to help.. Yes I did stack the wires, lead wire longer then another shorter and tape and lube etc...

I had a helper....he pulled the line as I lubed it up and feed it. The sweeps we're about 100 ft from eachother. There was a small curve that I made happen with a heat gun. Even getting it through the LBs wasn't hard at all.
You def won't have a problem if you go with #3 and #8 copper.
It's like doing ****, patience and plenty of lube and you'll be fine!

 

[Bert_]

1 1/2 is fine. I pulled 1/0 though 1 1/2 not long ago. It was about 100' with a couple 90*'s and an lb. It pulled fine by hand. It was even urd which is twisted and doesn't pull that good.

 

[dogdog]

i had a helper....he pulled the line as i lubed it up and feed it. The sweeps we're about 100 ft from eachother. There was a small curve that i made happen with a heat gun. Even getting it through the lbs wasn't hard at all.
You def won't have a problem if you go with #3 and #8 copper.
It's like doing ****, patience and plenty of lube and you'll be fine!

lmfao