100 amp, not 90

[Mx391]

Yes I know another 100 amp sub panel thread

Seems like everytime someone asks, it always derails into "just do 90 amp breaker with 2-2-2-4 AL. Well I want to feed my sub panel with a 100 amp breaker, not a 90.

I've got access to a code book, but it's way too confusing for me to read.
The littler flyer thing at lowes says I can run 2-2-2-4 Cu and be ok for up to 130 amps. I just want to double check with yall to make sure.

Wire will be in ran inside 2" pvc conduit and its about a 80ft run. Will #2 Cu wire be ok for my 100amp sub panel?

 

[Bad Habit]

Simple answer - yes (just make sure the insulation is rated at 75c or more, THWN, etc, most common these days for individual conductors)

 

[Norcal]

If you want 100A and insistent on copper use 3 AWG rather than 2 AWG save some coin that way. You wil not find it at a big box store going to have to go to a proper supply house.

 

[Mx391]

If you want 100A and insistent on copper use 3 AWG rather than 2 AWG save some coin that way. You wil not find it at a big box store going to have to go to a proper supply house.

Im ok with copper or AL, I just wanting 100 amps, not 90.

 

[alfredeneuman]

If you are OK, as you say with aluminum.....Use #1 with a #6 ground.

 

[Mx391]

If you are OK, as you say with aluminum.....Use #1 with a #6 ground.

I was worried about a #1 AL fitting inside the breaker. Shouldn't have any problems?

 

[sberry]

It will fit the breaker.

 

[mm08822]

Many 100A cb's will accept up to 2/0. Check the specs for the panel mfr you plan on using.

I would definitely go with AL - save a lot vs. CU.

 

[Slowgsr]

I've never pulled AL in my life! Always copper. Engineers always spec it.

 

[radio63]

I did what you are planning on doing. 100 amp CB in main panel, 100 amp CB in sub panel. 3 AWG Copper. Wire is THHN/TWHN. All through a 2 inch PVC conduit. All installed and working fine. I always prefer copper instead of aluminum. Just my preference.

 

[75gmck25]

The reason you see so many recommendations for 90 amps and 2-2-2-4 AL MHF is that the wire is very common and relatively cheap. I don't know the price of CU wire for 100 amps, but I'm sure there is a fairly big price difference. However, in the grand scheme of garage construction, a little more money for CU feeder wire is not that significant.

Bruce

 

[Mx391]

The reason you see so many recommendations for 90 amps and 2-2-2-4 AL MHF is that the wire is very common and relatively cheap. I don't know the price of CU wire for 100 amps, but I'm sure there is a fairly big price difference. However, in the grand scheme of garage construction, a little more money for CU feeder wire is not that significant.

Bruce

Exactly my thoughts. A little extra wont hurt. I've already went over my budget, whats a little more

 

[exranger06]

If you use #3 copper, you can use a #8 copper for the ground wire. That's what I ran to my subpanel, although it's hooked up to a 90 amp breaker. For a while I thought I was going to use #2 Al, so I bought a 90 amp breaker, then i ended up using copper.

 

[wyliesdiesels]

Yes I know another 100 amp sub panel thread

Seems like everytime someone asks, it always derails into "just do 90 amp breaker with 2-2-2-4 AL. Well I want to feed my sub panel with a 100 amp breaker, not a 90.

I've got access to a code book, but it's way too confusing for me to read.
The littler flyer thing at lowes says I can run 2-2-2-4 Cu and be ok for up to 130 amps. I just want to double check with yall to make sure.

Wire will be in ran inside 2" pvc conduit and its about a 80ft run. Will #2 Cu wire be ok for my 100amp sub panel?

The code book is not that confusing when you go to the right chart and understand the basics of temperature ratings.

The 90* column that 130a is under for #2 cu, is only to be used for derating. So you would use the next column to the left which is 115a for #2 cu.

But unless you have a very long run, #2 cu would be overkill for 100a. Go with #3 cu instead. Or switch to al #1 and save some money.

Dont forget to isolate the neutral in the subpanel and add 2 ground rods.

 

[Mx391]

The code book is not that confusing when you go to the right chart and understand the basics of temperature ratings.

The 90* column that 130a is under for #2 cu, is only to be used for derating. So you would use the next column to the left which is 115a for #2 cu.

But unless you have a very long run, #2 cu would be overkill for 100a. Go with #3 cu instead. Or switch to al #1 and save some money.

Dont forget to isolate the neutral in the subpanel and add 2 ground rods.

Thanks for the info!I already installed both ground rods. They are 8ft apart. Really tough to pound into the hard as rock TN dirt! I used a #6 ground wire from panel to ground rods.

 

[outdoorspace]

I read that copper plated ground rods last much longer than galvanized ones. Anyone else hear this?

 

[theoldwizard1]

Im ok with copper or AL, I just wanting 100 amps, not 90.

Go with #2 USE-2 copper ! That is what all the cool kids use. 2-2-2-4 USE-2 is about $5.50/ft.

Besides that extra couple hundred dollars are just burning a hole in your pocket !

 

[wyliesdiesels]

Go with #2 USE-2 copper ! That is what all the cool kids use. 2-2-2-4 USE-2 is about $5.50/ft.

Besides that extra couple hundred dollars are just burning a hole in your pocket !

Cant use it indoors

 

[theoldwizard1]

Cant use it indoors

Wire will be in ran inside 2" pvc conduit and its about a 80ft run.

I don't think 80ft would be indoors. Could be wrong.

 

[exranger06]

I don't think 80ft would be indoors. Could be wrong.

Unless the main panel AND the subpanel are mounted on the exterior walls of the buildings, the wire will be going inside a building at some point.

 

[mm08822]

You will have plenty of room in 1.5" conduit for 3-3-4-8(green) xhhw CU conductors.

Run the conduit panel to panel and eliminate jboxes and any splices.

The #4 can be taped white and #8 has to be green or bare.

 

[wyliesdiesels]

I don't think 80ft would be indoors. Could be wrong.

Unless the main panel AND the subpanel are mounted on the exterior walls of the buildings, the wire will be going inside a building at some point.

bingo

 

[Mx391]

I got 10ft of 1-1-1-4 SER to go from house panel to junction box in the crawl space. Then I got #1 AL xhhw to go from inside junction box, through the conduit into the shop panel. Thanks for the info guys!