Author Topic: Can I install my sub-panel?  (Read 593 times)

Jon Bon

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Can I install my sub-panel?
« on: January 10, 2018, 08:03:29 AM »
So my electrician is either busy or lazy or both, so I was thinking about doing my own sub-panel.

Backstory: Detached garage, panel will be approximately 40 feet from existing panel.  100 amp service into 150 amp main panel. 1.5 inch underground conduit already buried. I understand about not bonding the sub-panel, and I have run circuits myself before. This is all permitted and above board.  I have a very friendly code department (to the homeowner)

Questions:
1. Can I DIY?
2. What type of wire do I run to handle 100 amps?
3. Code Pitfalls to watch out for?


Ill take any nuggets of wisdom you might have, thanks all!



ncornilsen

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Re: Can I install my sub-panel?
« Reply #1 on: January 10, 2018, 08:06:39 AM »
You should be fine to DIY this... in Oregon at least, you can do that work if you have a permit.

BudgetSlasher

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Re: Can I install my sub-panel?
« Reply #2 on: January 10, 2018, 03:47:40 PM »
The first thing we did when we moved in was add 2 100-amp sub-panels (DIY'ed) for a total of 48 new available circuits. We've already used over half of those.

If I recall right, we used 1/0 aluminum wire.

Jon Bon

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Re: Can I install my sub-panel?
« Reply #3 on: January 10, 2018, 05:05:16 PM »
The first thing we did when we moved in was add 2 100-amp sub-panels (DIY'ed) for a total of 48 new available circuits. We've already used over half of those.

If I recall right, we used 1/0 aluminum wire.


Grow operation right? :-) I guess bitcoin mining would be more 2018.

Can anyone tell me what kind of wire I need? I think I need #2, but its got to be a different kind because it is going underground?

https://www.homedepot.com/p/Southwire-By-the-Foot-2-2-2-4-Black-Stranded-Al-Quad-Dyke-URD-Cable-55417399/205001803?cm_mmc=Shopping%7cTHD%7cG%7c0%7cG-VF-PLA-D27E-Electrical%7c&gclid=Cj0KCQiAkNfSBRCSARIsAL-u3X9LL1nHFohw1Ivxrl_PE55DcTp_eVT-ZpVwICxQsan4BJiS6gshQ28aAn8NEALw_wcB&gclsrc=aw.ds&dclid=CIf_nbfKztgCFZNqAQodl8YHwQ

BudgetSlasher

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Re: Can I install my sub-panel?
« Reply #4 on: January 10, 2018, 06:11:49 PM »
The first thing we did when we moved in was add 2 100-amp sub-panels (DIY'ed) for a total of 48 new available circuits. We've already used over half of those.

If I recall right, we used 1/0 aluminum wire.


Grow operation right? :-) I guess bitcoin mining would be more 2018.

Can anyone tell me what kind of wire I need? I think I need #2, but its got to be a different kind because it is going underground?

https://www.homedepot.com/p/Southwire-By-the-Foot-2-2-2-4-Black-Stranded-Al-Quad-Dyke-URD-Cable-55417399/205001803?cm_mmc=Shopping%7cTHD%7cG%7c0%7cG-VF-PLA-D27E-Electrical%7c&gclid=Cj0KCQiAkNfSBRCSARIsAL-u3X9LL1nHFohw1Ivxrl_PE55DcTp_eVT-ZpVwICxQsan4BJiS6gshQ28aAn8NEALw_wcB&gclsrc=aw.ds&dclid=CIf_nbfKztgCFZNqAQodl8YHwQ

I wish is was anything that exciting. Mostly its been things like the boiler and the washing machine should each have a dedicated circuit (and central vac and so on), not be on the same circuit . . . oh and adding a fully electric brewery (I guess that was exciting).

Jon Bon

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Re: Can I install my sub-panel?
« Reply #5 on: January 11, 2018, 11:21:16 AM »
The first thing we did when we moved in was add 2 100-amp sub-panels (DIY'ed) for a total of 48 new available circuits. We've already used over half of those.

If I recall right, we used 1/0 aluminum wire.


Grow operation right? :-) I guess bitcoin mining would be more 2018.

Can anyone tell me what kind of wire I need? I think I need #2, but its got to be a different kind because it is going underground?

https://www.homedepot.com/p/Southwire-By-the-Foot-2-2-2-4-Black-Stranded-Al-Quad-Dyke-URD-Cable-55417399/205001803?cm_mmc=Shopping%7cTHD%7cG%7c0%7cG-VF-PLA-D27E-Electrical%7c&gclid=Cj0KCQiAkNfSBRCSARIsAL-u3X9LL1nHFohw1Ivxrl_PE55DcTp_eVT-ZpVwICxQsan4BJiS6gshQ28aAn8NEALw_wcB&gclsrc=aw.ds&dclid=CIf_nbfKztgCFZNqAQodl8YHwQ

I wish is was anything that exciting. Mostly its been things like the boiler and the washing machine should each have a dedicated circuit (and central vac and so on), not be on the same circuit . . . oh and adding a fully electric brewery (I guess that was exciting).

A brewery is very exciting! I've never done electric but the advantages must be pretty great.... Maybe ill include an extra 50 amp breaker in the garage......


Cadman

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Re: Can I install my sub-panel?
« Reply #6 on: January 11, 2018, 11:47:55 AM »
As long as your termination connections are sufficiently rated temp-wise, you should be able to get away with #2 copper. If you've got 60C terminations, then you're limited to 90A, and good luck finding a breaker that size.

Since you already have conduit installed, what you want is THHN wire. A quick check of conductor-fill in conduit and raceways shows 1-1/2" should be fine for your two hots, a neutral and the ground. It might be cheaper to buy a 100' roll of black wire than to try to figure out exactly how much you need and pay per foot (and come up short). That should cover both of your hots, one of which you can tag at each end with red electrical tape.  If you find an exceptional deal on wire, you can technically use black wire for the neutral (it's allowed by the NEC for conductors larger than #6) and tag it with white tape, but if white THHN is the same price, I wouldn't bother.

Jon Bon

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Re: Can I install my sub-panel?
« Reply #7 on: January 11, 2018, 12:01:25 PM »
As long as your termination connections are sufficiently rated temp-wise, you should be able to get away with #2 copper. If you've got 60C terminations, then you're limited to 90A, and good luck finding a breaker that size.

Since you already have conduit installed, what you want is THHN wire. A quick check of conductor-fill in conduit and raceways shows 1-1/2" should be fine for your two hots, a neutral and the ground. It might be cheaper to buy a 100' roll of black wire than to try to figure out exactly how much you need and pay per foot (and come up short). That should cover both of your hots, one of which you can tag at each end with red electrical tape.  If you find an exceptional deal on wire, you can technically use black wire for the neutral (it's allowed by the NEC for conductors larger than #6) and tag it with white tape, but if white THHN is the same price, I wouldn't bother.

I spoke with the city and he suggested 2-2-2-4 aluminum that I listed in the link above. Why the difference?


Bourbon

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Re: Can I install my sub-panel?
« Reply #8 on: January 11, 2018, 12:22:47 PM »
As long as your termination connections are sufficiently rated temp-wise, you should be able to get away with #2 copper. If you've got 60C terminations, then you're limited to 90A, and good luck finding a breaker that size.

Since you already have conduit installed, what you want is THHN wire. A quick check of conductor-fill in conduit and raceways shows 1-1/2" should be fine for your two hots, a neutral and the ground. It might be cheaper to buy a 100' roll of black wire than to try to figure out exactly how much you need and pay per foot (and come up short). That should cover both of your hots, one of which you can tag at each end with red electrical tape.  If you find an exceptional deal on wire, you can technically use black wire for the neutral (it's allowed by the NEC for conductors larger than #6) and tag it with white tape, but if white THHN is the same price, I wouldn't bother.

I spoke with the city and he suggested 2-2-2-4 aluminum that I listed in the link above. Why the difference?

I had a family member helping when we did our garage, but I was looking at that 2-2-2-4 aluminum feeder wire.  If it is what I am thinking of, that is intended for direct burial and is not good for conduit.  It was a slight savings over copper, but ultimately just got THHN, thankfully from a supply house with his discount.

Cadman

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Re: Can I install my sub-panel?
« Reply #9 on: January 11, 2018, 05:33:25 PM »
I spoke with the city and he suggested 2-2-2-4 aluminum that I listed in the link above. Why the difference?

Bourbon's right, 2-2-2-4 would be for direct burial, or in some cases, overhead use if marked. Typical terms are USE, URD, Triplex. etc. #2 aluminum is also pushing it for 100A (rated 90A at 75C service). Being the conductors are physically larger than CU, you'll want to check conduit fill and temp rise with that approach. But I tell you what, I wouldn't want to try to fish that stuff through conduit unless you had a pusher and it was a direct shot. There's also the matter of terminating the physically larger conductor in a breaker at your source panel.

If this were a couple hundred feet, I'd lean towards the AL for savings, but if I were in your shoes, I'd go with the cu THHN. But either way, I'd shop around. HD tends to be pricey on wire.

Jon Bon

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Re: Can I install my sub-panel?
« Reply #10 on: January 12, 2018, 06:36:04 AM »
I spoke with the city and he suggested 2-2-2-4 aluminum that I listed in the link above. Why the difference?

Bourbon's right, 2-2-2-4 would be for direct burial, or in some cases, overhead use if marked. Typical terms are USE, URD, Triplex. etc. #2 aluminum is also pushing it for 100A (rated 90A at 75C service). Being the conductors are physically larger than CU, you'll want to check conduit fill and temp rise with that approach. But I tell you what, I wouldn't want to try to fish that stuff through conduit unless you had a pusher and it was a direct shot. There's also the matter of terminating the physically larger conductor in a breaker at your source panel.

If this were a couple hundred feet, I'd lean towards the AL for savings, but if I were in your shoes, I'd go with the cu THHN. But either way, I'd shop around. HD tends to be pricey on wire.

Thanks Cadman, could you um, include a link (HD, Lowes) for what you would buy?! Honestly this whole thing is pretty confusing me. I can wire up 12-2 outlets and circuits all day, but this is a little beyond my skill set in terms of sizing this correctly!

I appreciate it!


Cadman

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Re: Can I install my sub-panel?
« Reply #11 on: January 12, 2018, 09:20:34 AM »
No problem. What you're looking for is THHN / THWN /THWN-2 (most companies just make one version to the most stringent requirement and stamp multiple nomenclatures on it) in a #2 gauge (2 AWG).

Here's a handy ampacity chart, along with some calculators in the left column. At 40' with the load you're considering, voltage drop shouldn't be much of a problem.  http://www.cerrowire.com/ampacity-charts

If you really can get from one panel to the other in 50' or less, terminal to terminal, then you might consider buying a 150' roll of black and using that for all three runs if it's cheaper (marking with colored tape as appropriate). Otherwise, here's a couple links for 'by the foot'.

https://www.wireandcableyourway.com/2-awg-thhn-building-wire.html
https://www.homedepot.com/p/Southwire-By-the-Foot-2-Black-Stranded-CU-SIMpull-THHN-Wire-20502199/204632781

I see you're in the midwest, if you have a Menards around, they've got it for $1.59/ft. This week is 11% off plus use the Menards card for another 2% bringing it down to $1.38.

You're on your own for the ground conductor sizing. I'd suspect #4 would be adequate but run it by your AHJ first. And make sure you're comfortable with all of this before proceeding.

Jon Bon

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Re: Can I install my sub-panel?
« Reply #12 on: January 12, 2018, 09:49:43 AM »
No problem. What you're looking for is THHN / THWN /THWN-2 (most companies just make one version to the most stringent requirement and stamp multiple nomenclatures on it) in a #2 gauge (2 AWG).

Here's a handy ampacity chart, along with some calculators in the left column. At 40' with the load you're considering, voltage drop shouldn't be much of a problem.  http://www.cerrowire.com/ampacity-charts

If you really can get from one panel to the other in 50' or less, terminal to terminal, then you might consider buying a 150' roll of black and using that for all three runs if it's cheaper (marking with colored tape as appropriate). Otherwise, here's a couple links for 'by the foot'.

https://www.wireandcableyourway.com/2-awg-thhn-building-wire.html
https://www.homedepot.com/p/Southwire-By-the-Foot-2-Black-Stranded-CU-SIMpull-THHN-Wire-20502199/204632781

I see you're in the midwest, if you have a Menards around, they've got it for $1.59/ft. This week is 11% off plus use the Menards card for another 2% bringing it down to $1.38.

You're on your own for the ground conductor sizing. I'd suspect #4 would be adequate but run it by your AHJ first. And make sure you're comfortable with all of this before proceeding.

Thanks Cadman, I am sure I can get the right wire, I am less sure I can get it thru the conduit! Ill check menard, half of my question is I can never see any of this stuff in the store.

I guess worst case I can run a 60 amp with a smaller wire. Ill keep you guys posted, aka I will come back when I have more questions...

**EDIT**

I need 4 connections, 2 hot 1 neutral and 1 ground, but half of my confusion on this is it says "number of connections 1" So would I need four of these wires?

Menards has them in stock I might just go pick it up there so I can put my hands on it. Also gonna stop by an electrical supply store hopefully someone can get me straightened out!

FWIW Money is no object if it means taking 20 mins to pull it thru the conduit or 2 days.





« Last Edit: January 12, 2018, 09:58:01 AM by Jon Bon »

Cadman

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Re: Can I install my sub-panel?
« Reply #13 on: January 12, 2018, 10:15:28 AM »
Not sure where you're seeing 'number of connections 1' but your original statement is correct, you just need 2 hots, 1 neutral and a ground (one conductor per). Menards will also have the pull lube and the polyester pulling line (don't use string, it'll stretch too much). You can suck this through the conduit with a shop vac if you ball up some plastic or bubble wrap to tape to the end of the pull line. Check out Youtube, there are some helpful vids.

Jon Bon

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Re: Can I install my sub-panel?
« Reply #14 on: January 12, 2018, 11:55:41 AM »
Not sure where you're seeing 'number of connections 1' but your original statement is correct, you just need 2 hots, 1 neutral and a ground (one conductor per). Menards will also have the pull lube and the polyester pulling line (don't use string, it'll stretch too much). You can suck this through the conduit with a shop vac if you ball up some plastic or bubble wrap to tape to the end of the pull line. Check out Youtube, there are some helpful vids.

Ok I got you!

Some of those are just wire, but others are 4 wires sold in a set, so I was kind of confused about what I needed. By my math Aluminum is going to be $75-100 and copper is going to be north of $200.

Thanks so much I appreciate it!

Ill post back when I've spent a whole day trying to run the wire through the conduit and give up and call an electrician...


Bourbon

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Re: Can I install my sub-panel?
« Reply #15 on: January 16, 2018, 09:35:47 AM »
Not sure where you're seeing 'number of connections 1' but your original statement is correct, you just need 2 hots, 1 neutral and a ground (one conductor per). Menards will also have the pull lube and the polyester pulling line (don't use string, it'll stretch too much). You can suck this through the conduit with a shop vac if you ball up some plastic or bubble wrap to tape to the end of the pull line. Check out Youtube, there are some helpful vids.

I was just in process of writing this up and saw you already have it.  I tied a plastic grocery bag to the end of the pulling string and the shop vac sucks it through nicely.  Always easier if you are pushing and pulling.  They do make a lube for this purpose, but depending on your conduit size you should be fine without it.  Also depends on how many 90's you have vs straight pipe.

Jon Bon

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Re: Can I install my sub-panel?
« Reply #16 on: January 16, 2018, 10:36:28 AM »
Not sure where you're seeing 'number of connections 1' but your original statement is correct, you just need 2 hots, 1 neutral and a ground (one conductor per). Menards will also have the pull lube and the polyester pulling line (don't use string, it'll stretch too much). You can suck this through the conduit with a shop vac if you ball up some plastic or bubble wrap to tape to the end of the pull line. Check out Youtube, there are some helpful vids.

I was just in process of writing this up and saw you already have it.  I tied a plastic grocery bag to the end of the pulling string and the shop vac sucks it through nicely.  Always easier if you are pushing and pulling.  They do make a lube for this purpose, but depending on your conduit size you should be fine without it.  Also depends on how many 90's you have vs straight pipe.

Thanks! I ordered some lube (heh) for $7 so I figured might as well if it even helps a little.


So I just got quoted from my electrician (who woke up from hibernation I guess?) wanted 700 bucks for the job which feels pretty high since I already have ordered the wire.

A panel and a breaker should be $100 bucks from my big box store I guess I will try it this weekend!