Pulling new cable to garage - questions

[scootermcrad]

Hey guys!

Well, I've decided that my somewhat under-powered garage really needs to have a new cable pulled to its 120 AMP sub-panel. The garage is attached to the house via a breezeway with an attic space. Current wire passes through this, but is not run very well.

It was suggested by a very reliable source that I should run 2 AWG THHN type wire. Big stuff, but should be just right for the amperage load the garage will see. (lathe, mill, welders, compressor, few lights, and a fridge). The wire will be pulled through the crawl space, up through the wall of the house and into the attic of the breeze way, and down into the panel in the garage. The walls that the wire will be pulled through are completely open right now for a renovation, so this is a great time to pull it.

Questions:

* Should I run a 3 conductor or 4 conductor?
* What TYPE of breaker is the thing to buy these days?
* Are there similar wire types to 2 AWG THHN worth considering?
* what would one expect to pay per foot for this type of wiring? (need around 140 feet, I think)
* Do I need to run conduit under the house in the crawl space, or just string it and support from the floor joists? How about the walls? Just run it like any other kind of wire through the walls?

 

[pattenp]

You can use 4 conductor SER cable and won't need any conduit unless the cable will be exposed to possible damage. It can be run through the attic and in walls just as you would run NM (Romex) cable. I know you said 120A sub-panel, but if you're talking about #2 Al, it's only good to 90A @ 75C degrees. Also there are restrictions on SER when ran within insulation that the Amp rating will need to be reduced based on 60C degrees which will make it 75A. And also being over 100' you need to consider voltage drop.

Not knowing the exact details of where and how this wire will be run. You need something like Aluminum 1/0-1/0-1/0-2 SER. This will be good for 100A @ 60C if traveling within insulated walls. Hook it in your main panel using a 100A double pole breaker.

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet273

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[scootermcrad]

I'm thinking I would almost rather go copper, although more expensive. Less resistance over that kind of distance. Is that stupid? Or just stick with AL SER wire?

I have #6, 4-conductor SER (or maybe SE) right now and I'm doing a renovation on an adjoining room that requires me to move the cable, which means it will be 10-12 feet too short. I don't like the idea of extending that cable, since it's not going to work for my power needs anyway. Best time to make the change is while I have it all wide open.

I won't be pushing the 120A panel to 120A, though. Realistically, I'll probably never see numbers over 70A or 80A PEAK, and never fill even half the slots in the box. Worst case would be the air compressor (35A peak) and fridge would kick on while welding something big. I figure if i'm going to go through all the trouble of running new cable then I may as well not limit myself in that department. I'm building a new garage sometime in the next couple years, and all the equipment will be moved out, except maybe the compressor. Loads will be moved to new garage at that point.

Wire will be run through one insulated wall. Straight shot, from plate to plate.

 

[scootermcrad]

Probably just best to stick with AL and run a 2-2-2-4 SER, huh? Seems to be reasonably priced, also.

 

[rburke65]

I don't really think you will come any where near 100A. being a one man garage. Now if you had 5 or 6 folks in there.......even still.....100A. Is a lot.You will be fine with the 2 AL.

 

[scootermcrad]

I don't really think you will come any where near 100A. being a one man garage. Now if you had 5 or 6 folks in there.......even still.....100A. Is a lot.You will be fine with the 2 AL.

My feelings exactly!

So what about the main panel breaker? I will probably just limit it to 70 or 80. What should I look for? I know there are a couple different types to choose from. Not too familiar with the topic of breakers beyond rating.

 

[pattenp]

Probably just best to stick with AL and run a 2-2-2-4 SER, huh? Seems to be reasonably priced, also.

Because of the SER running within an insulated wall you are limited to 60C and #2-2-2-4 SER will be 75A, so you can use an 80A breaker to feed it since 80A is the next common size breaker. You need to get the same brand/style double pole breaker that the main panel is.

 

[scootermcrad]

Because of the SER running within an insulated wall you are limited to 60C and #2-2-2-4 SER will be 75A, so you can use an 80A breaker to feed it since 80A is the next common size breaker. You need to get the same brand/style double pole breaker that the main panel is.

Okay! Great! I will look for an 80A double pole.

I'm not sure what brand of panel I have. It's "old-ish". 80's, probably. Anyone recognize this layout? GE maybe?? I need to get a buddy and go through all the circuits and see what is what. Have at least 4 breakers not even being used. Since the panel was installed (several PO's ago), it was never marked properly. Not even sure what breaker goes to the garage. I suspect it's only a 40A. One day it will be replaced and updated.

 

[pattenp]

I think its a Siemens/ITE panel.

http://www.lowes.com/pd_322640-1318-80A+SIEMENS+2-POLE+B_0__?productId=3128661

 

[scootermcrad]

I think its a Siemens/ITE panel.

Okay! Great! THANKS! The newer 120A sub-panel in the garage is a Siemens, so maybe someone thought it clever to use the same make of panel. That would be handy.

And thanks for the link! That is helpful!

 

[scootermcrad]

So, just a quick clarification...

Since SER type wire is considered for use in Indoor and Outdoor environments, is it appropriate/to code to attach this to the floor joists in the crawl space? And I will NOT need conduit running through my insulated wall, correct? If I DO need conduit, what type of conduit would be recommended for the application?

 

[pattenp]

The SER cable can run along the bottom of floor joist and be supported by large staples or straps. In a wall cavity it does not need to be in conduit. If you do put it in conduit for protection reasons you can use 2" PVC.

 

[scootermcrad]

The SER cable can run along the bottom of floor joist and be supported by large staples or straps. In a wall cavity it does not need to be in conduit. If you do put it in conduit for protection reasons you can use 2" PVC.

Great! Thank you sir! I appreciate all your input!

Now, with all that being said... Any reason NOT to use the AL SER style cable for what I'm up to? Other option is to do individual 2 awg flexible copper conductors, but DAMN! Big bucks ($600+ for 500 feet WHOLESALE!) for something that is only a temporary solution for my shop space which will be used as simple car parking in a couple years.

 

[Aceman]

Any reason NOT to use the AL SER style cable for what I'm up to?

No, this is what it's made for.

 

[pattenp]

.... Other option is to do individual 2 awg flexible copper conductors......

If you run individual conductors they will need to be in conduit the whole way from panel to panel. #4 Cu THHN in conduit will give you a little more amp capacity than the #2 Al SER. The reason is the THHN in conduit can be sized at 75C, and the SER needs to be sized by 60C because of the wall you are placing the wire in is insulated.

 

[scootermcrad]

Thanks guys!

I really appreciate everyone's input. I think I'll be researching the Cu THHN individual conductors for the new garage/shop and just stick with the Al SER for this upgrade.

Everyone has been such a big help. Love this place!

 

[pattenp]

scoot, will the new garage be detached? If detached then the wire you can use will be a whole different story if being placed under ground. There are a few different options.

 

[scootermcrad]

scoot, will the new garage be detached? If detached then the wire you can use will be a whole different story if being placed under ground. There are a few different options.

Yeah, the new garage will be completely detached. Was going to bury some conduit for that one, but then that's just some initial thinking based on very little knowledge.

 

[pattenp]

Even though you can use direct bury cable, I think using conduit is smart. It is a good idea to come back here and get some info on wire types to use and what restrictions may exist on the use of different wire when you get close to starting on your shop. There have been people to come to this forum to ask questions after they've gotten wire only to find out they got the wrong stuff.

 

[scootermcrad]

Even though you can use direct bury cable, I think using conduit is smart. It is a good idea to come back here and get some info on wire types to use and what restrictions may exist on the use of different wire when you get close to starting on your shop. There have been people to come to this forum to ask questions after they've gotten wire only to find out they got the wrong stuff.

Yep! I agree completely! Going to actually start a whole thread just for the garage project, when comes time. Already sketching out ideas for the shop, too.

Thanks!

 

[scootermcrad]

Just stopped at Homeless Depot on my lunch break. they have 2-2-2-4 AL SER cable for $1.10 a foot! That seems like a pretty reasonable price, actually. That certainly won't burn my budget too bad! Was surprised how cheap it was. I figured it would be closer to $1.90+ a foot. I kicks checked to see if they had 1-1-1-3, but they didn't. Next size up was 4/0.

 

[scootermcrad]

Just an update, in case anyone else is going through this. I opted for 1-1-1-3 AL SER. A size larger than what I was planning on. Allowable Ampacities at 60C call for 85 AMPs I will size the breaker at either 70 or 80. 70 should be plenty and add a little safety buffer.

I also decided to go with a slightly smaller compressor for this garage and I'll leave it in there instead of moving it over to the new shop. This means less draw, further reducing my load. For the new shop, I will have a meter added and a new line dropped. Pretty reasonable to have done and this way if I end up running a small business out of that shop I can keep better track of my power consumption.

More updates as I do the install.

Thanks again for the help guys!

 

[ishiboo]

Just an update, in case anyone else is going through this. I opted for 1-1-1-3 AL SER. A size larger than what I was planning on. Allowable Ampacities at 60C call for 85 AMPs I will size the breaker at either 70 or 80. 70 should be plenty and add a little safety buffer.

I also decided to go with a slightly smaller compressor for this garage and I'll leave it in there instead of moving it over to the new shop. This means less draw, further reducing my load. For the new shop, I will have a meter added and a new line dropped. Pretty reasonable to have done and this way if I end up running a small business out of that shop I can keep better track of my power consumption.

More updates as I do the install.

Thanks again for the help guys!

For the future... 2-2-2-4 SER is good for 90A because you use the 75 degree table. Many people still breaker for 100A even though that's not correct.

Not sure what the price difference is, but 2-2-2-4 SER is uber easy to find and usually VERY reasonably priced as you found.

 

[pattenp]

For the future... 2-2-2-4 SER is good for 90A because you use the 75 degree table. Many people still breaker for 100A even though that's not correct.

Not sure what the price difference is, but 2-2-2-4 SER is uber easy to find and usually VERY reasonably priced as you found.

There is an exception on SE cable if run within thermal insulation. It needs to be sized from the 60C column. Having to use 60C depends on the length ratio within insulation to the length of the cable not within insulation.

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[scootermcrad]

For the future... 2-2-2-4 SER is good for 90A because you use the 75 degree table. Many people still breaker for 100A even though that's not correct.

Not sure what the price difference is, but 2-2-2-4 SER is uber easy to find and usually VERY reasonably priced as you found.

There is an exception on SE cable if run within thermal insulation. It needs to be sized from the 60C column. Having to use 60C depends on the length ratio within insulation to the length of the cable not within insulation.

*

I was following the rules for 60*C because it will be run through an insulated wall. Is that not correct?

Looking again at my loads. My TIG welder is calling for a 60 amp slow trip. May just go with the 80 amp breaker in the main panel.

Total length of cable will be around 65 or 70 feet. Length within insulated walls will be approximately 15 feet total.

 

[ishiboo]

I was following the rules for 60*C because it will be run through an insulated wall. Is that not correct?

Looking again at my loads. My TIG welder is calling for a 60 amp slow trip. May just go with the 80 amp breaker in the main panel.

If it goes continuously through an insulated wall, yes... you are correct.

 

[scootermcrad]

Tangent question...

For my TIG with the 60 amp slow-trip breaker, do I want 8-3 to the sub-panel or 8-2? Will only be about 20-25 in length.

 

[scootermcrad]

If it goes continuously through an insulated wall, yes... you are correct.

So I'm REALLY safe with an 80 amp, then, if that's the case. Correct?

 

[pattenp]

Tangent question...

For my TIG with the 60 amp slow-trip breaker, do I want 8-3 to the sub-panel or 8-2? Will only be about 20-25 in length.

What type wire are you running to the TIG? For 60A breaker you need #6.

 

[scootermcrad]

What type wire are you running to the TIG? For 60A breaker you need #6.

#6 it is, then. Do I want 6/2 or 6/3?

 

[pattenp]

To go back a post the 80A breaker is fine for the #2 feed to the sub.

#6 it is, then. Do I want 6/2 or 6/3?

You only need 6/2.

 

[scootermcrad]

To go back a post the 80A breaker is fine for the #2 feed to the sub.



You only need 6/2.

Sounds good for the 80A breaker. Did you mean #1 feed?

6/2. Great! Thanks!

Just realized what I typed. HAHA! 6/3? I have got my mind so wrapped up in household wiring that I've turned my brain to mush... I wouldn't need 6/3 for 220 single phase. Sorry for the silly question. Been a long day.

 

[pattenp]

Sounds good for the 80A breaker. Did you mean #1 feed?

6/2. Great! Thanks!

Just realized what I typed. HAHA! 6/3? I have got my mind so wrapped up in household wiring that I've turned my brain to mush... I wouldn't need 6/3 for 220 single phase. Sorry for the silly question. Been a long day.

I forgot you went with 1-1-1-3 Al SER. At 60C you can use a 90A breaker with the #1.

 

[scootermcrad]

I forgot you went with 1-1-1-3 Al SER. At 60C you can use a 90A breaker with the #1.

Cool! Thanks for all your input!