What wire for 100A feeder? Upgrade main to 200A?

[Jeepskate]

What wire for 100A feeder?

I have a 150A main in the house and bought a 125A sub to install in my yet to be built detached shop. I'll be running radiant floor heat at some point in the shop as well as a lift and a 220V MIG plus the usual lights, power tools, etc.

The main is on the east wall of the basement, so I need to run wire through/along the first floor joists about 36' west and about 12' south to get out the back side of the house, then I've got a buried run of about 130' to the shop (the plan is to trench and drop in 1 1/2" conduit for the electric and another 1" conduit for a couple of CAT5 runs) to the west of the house.

The electrician who my contractor uses was throwing around a bunch of numbers & letters as he was sorting things out in his head while looking things over, but i wasn't around for what he settled on (I was having some rocks delivered and went to help the guy get them off of his trailer). The only thing that I've picked up on is #3 copper. I want to do the runs myself since I'm perfectly capable of handling the grunt work instead of paying him for that part, and I'll just have him make the connections. At one point he talked about using two different types (the letters) of wire, one for inside the other for outside with a box mounted on the outside of the house for the junction, but it sounds like he settled on using the same stuff and possibly just doing one straight run with it. Does the single run sound like a good idea, or would the junction box outside make more sense even if the same type of wire is being used the whole way? What type/types of wire should I be sourcing for this? Thanks. Attached pic is of my lot (yellow line) and the red box is about where the shop will sit.

 

[cncjerry]

Just the first thing that popped in to my head is putting a 200 amp panel in the garage and making the house as a sub panel a option. You will need to have your utility company move your entrance to the garage but just a thought. Then you can upgrade your house panel to a 160 amp.

 

[Jeepskate]

The work and expense for that would be financially prohibitive. My power comes off of a pole in the edge of the woods downhill/north from the house east of the well and the house...that's why my entrance & panel are on the east side of the house. I'd probably have to go west across the front yard, under the driveway, then head south to the garage. Then I'd still need the feeder between the garage & house and still need the 200A main plus a 160A sub. I'd consider it if everything wasn't on the opposite side of the house. Whole lotta cost and disruption for little to no gain that I can see. Seems a lot simpler and cheaper to just upgrade the main in the house with the same brand/type unit so that the breakers swap over.

 

[Stuart in MN]

First thing to ask is will the electrician be okay with you providing and installing the wire yourself? It is kind of like bringing your own parts to the auto repair shop and asking them to put them on for you - some electricians may agree to it, others won't because 1) you're cutting into his potential profits and 2) he may not want to stand by work that includes cable and conduit he didn't install himself.

 

[Jeepskate]

I'll check into that, Stuart. I could do the whole thing myself (a buddy and I installed my standby generator), but don't want to risk running afoul of the codes and my buddy is working down in Texas now and I wouldn't want to bother him with this on one of his short trips back home. With the dead housing market around here (it was dead here before the rest of the US) I know the electrician doesn't have any work right now, so I may be able to work a deal to lower his bill if I just dig the trench and bore the holes and leave the rest to him (I'll run my own CAT5 though). I'm looking at an $1800 estimate including the materials (but I just bought the sub myself yesterday for $31, bought the 100A breaker for my main this evening for $10, and found a good deal on the PVC conduit this afternoon, so I'll probably go ahead and buy that myself too) and don't see the point in paying to have him trench outside and bore the holes inside when I can do that myself...I'll probably bore the holes this weekend. Let's face it, anyone with opposable thumbs can stick the wire in the conduit and lay it in the trench and it only takes slightly more skill to run a drill to bore the holes and run the wire through them. My generator works fine and I did all of the coax and CAT5 cabling in my house (had no CAT5 and the coax was just run up through holes in floors & ceilings...I ran everything in the walls and installed jacks in wall plates). I really only need the electrician to install the sub to code. Not really much for him to have to stand by other than the sub being installed to code. The contractor was the one who suggested that I go this route in order to save some cash, since he knows I could actually do the whole job myself (including assembling the building if I had a couple of guys to help me).

 

[Jeepskate]

Oops...I goofed...I have 150A service in the house (main is in my office), so scratch the whole 200A panel aspect of this. What's the recommended wire for my run? I know #3 copper, but don't know any designation beyond that.

 

[Jeepskate]

Anybody?? Did I offend the electricians by not wanting to pay one for the grunt work portion of the job?

 

[structures282]

#3 copper will carry your 100 amps per NEC 310.16 but for a sub panel as you describe you will need 4 wires and 1.5in DIA pipe sounds a little tight. Check out this webpage for some good DIY info.

http://www.selfhelpandmore.com/home...o-dwellings/wiring-a-detached-garage-2002.php

It's more than just wire DIA also there's the rating stamped on the side as well. So I believe URD can not enter the house and use-2 wire has to be dual rated USE-2 and RHH RHW to be able to enter house walls. That is most likely why he was talking of using 2 different types of wire. You might consider a 1-1-1-3 USE-2 RHH rated wire... may be cheaper... I dunno $2/foot for all 4 wires.

Anyway this is my vague understanding, I'm by no means an electrician. There's some electricians around GJ that usually have much more confident advice. Or if you have an electrical inspector in your area you may be able to contact them and get the best answer. I'm just restating what I've picked up along the way. I'm in the process of doing what you are doing. Powering a detached shop.

 

[tfi racing]

1 1/2 conduit is more than large enough for a #3 Cu service for your garage and should make for an easy pull.Maybe your electrician was considering using 3/3 NMD for the interior part of the run across the basement and making a transition exiting the house.

I never get offended by anyone offering to do the grunt work himself,as long as they do it properly and the way I need it done.You're right,a donkey with opposable thumbs could do about 90% of any electrical work,and would likely have a better personality as well!

 

[Jeepskate]

Thanks for the info. Excellent link and good idea on contacting the inspector...he should be able to tell me what he'd be looking to see run. The electrician seemed like a nice guy...he hung around and chatted for a bit after the contractor left (that's how I know he doesn't have any work right now). If I could afford it, I'd just pay him to do the whole thing and be done with it, but I've got a pretty tight budget, so I'm putting in sweat equity where I can.

 

[Jeepskate]

Well, thanks to zoning, my plans have changed. I found out that because I'm zoned residential rural and have a 'flag' lot (shape of the lot...main lot is the flag, portion with the driveway is the pole) I have a 75' min. setback from *all* of my property lines. So, ended up down in the clearing near the pole with the transformer and will end up with a separate meter. I got my zoning permit last week and hope to have the building permit this week so that we can break ground next week.

 

[custom1]

Wow, I have never heard of that rule. 75' setback sounds crazy to me. I guess they don't want you building along the "pole" portion of the property, but what would it hurt for you to put it where you wanted in the first place?

Can you apply for a variance? It might cost a couple of bucks, but it would be worth it and I don't see where your neighbors would complain.

 

[Jeepskate]

On a normal residential rural lot it would be 75' front, 50' rear, 25' sides...that alone blew me out of the water, then I picked another spot near where I ended up, called the inspector to ask if my 800'+ 'pole' covered me for the 75' since I'd be about 30' away from the front of the 'flag', and he told me to disregard what he told me earlier (75/50/25) and that the rule for me was 75' all the way around. I guess worst case scenario, you could end up with 75' between the back of someone's house/building and the side of the next house/building and they want a 100' space at the back.

I could apply for a variance, but that takes time & money and there's no guarantee that they'd grant it which would put me right where I am now only $125 lighter in the pockets and 2 or more weeks behind. I'd have to go around to everyone who adjoins my property (including across the street) and tell them what's going on and supply their names & addresses, plus the clause for variances here reads that you basically have to have a hardship case and no other place to fit the building. In a way it works out better as the original site is where my fire pit is (backyard is the septic field), overflow parking, and the way that I pull in when I have a trailer so that I can turn around or back up to the garage.