Pole barn feeder help

[Speedway]

I am trying to draw up a plan so I can pull a permit to run a feeder to my pole barn and have a few questions.
I am trenching in 2" pvc conduit, total of 200 feet with 2 45's in the mix to feed 2-2-2-4 use-2 aluminum in it.
I plan to feed it with a 50 amp breaker to a 100 amp breaker in the barn panel.

Can I use a 2" LB to splice the use-2 to #4 thhn on each end to go into the buildings or wil I need junction boxes?

Is there a certain height from grade for the LB to enter the buildings?

The barn panel will be 12' lower in elevation than the house panel, will this be an issue using conduit?

I'm sure I will have more questions once I get going on this..

Thanks

 

[383 240z]

Just did a similar but shorter run. My electrician put a 50 amp breaker both in the shop, and in the barn.

 

[wyliesdiesels]

What kind of loads in the shop?

At that distance i recommend wire bigger than #2 AL

And no an LB will be too small to do splices in.

 

[Speedway]

What kind of loads in the shop?

At that distance i recommend wire bigger than #2 AL

And no an LB will be too small to do splices in.

Mill, lathe and air compressor all of which are currently running off of a 20 amp 110 breaker but can be wired 240 and 10 4' t8 lights.

Just did a similar but shorter run. My electrician put a 50 amp breaker both in the shop, and in the barn.

I thought I had to have a 60 amp disconnect for a sub panel?

 

[pattenp]

Is the 2-2-2-4 URD wire? It you use MHF you can run it from panel to panel in conduit without splices. I assume you are thinking of splicing THHN because USE-2 only rated wire needs to be terminated outside the structure. Also if your max load is 50A then the #2 Al should be fine at 200 ft.

 

[pattenp]

I thought I had to have a 60 amp disconnect for a sub panel?

Not for a branch feed. You are thinking a service feed disconnect. NEC 230.79.

Edit: I need to correct myself. I forgot it does apply to branch feeds. NEC 225.39.


*

 

[wyliesdiesels]

Mill, lathe and air compressor all of which are currently running off of a 20 amp 110 breaker but can be wired 240 and 10 4' t8 lights.

Any heating, AC, welders or large motors?

If not and thats all the load u will have then as pattenp said, u will be fine.

I would go with MHF instead of URD.

Not for a branch feed. You are thinking a service feed disconnect. NEC 230.79.

Edit: I need to correct myself. I forgot it does apply to branch feeds. NEC 225.39.


*

I often forget about 225.39(D) but question the reasoning behind it. Any ideas?

 

[Speedway]

Is the 2-2-2-4 URD wire? It you use MHF you can run it from panel to panel in conduit without splices. I assume you are thinking of splicing THHN because USE-2 only rated wire needs to be terminated outside the structure. Also if your max load is 50A then the #2 Al should be fine at 200 ft.

The wire I have is single rated USE-2 xlpe I was shopping for MHF when this was offered up for beer money.
The shop I have been using for the last 10 years is wired with 10UF from a 30 amp double pole breaker in the house and has never tripped it. For what little I do in the shop I'm sure a 50 amp feeder will be sufficient.

 

[Speedway]

Any heating, AC, welders or large motors?

If not and thats all the load u will have then as pattenp said, u will be fine.

I would go with MHF instead of URD.



I often forget about 225.39(D) but question the reasoning behind it. Any ideas?

No AC, wood stove for heat, largest motor is 2hp on the mill and the welder is a gasoline powered Miller legend

For what I have in the wire I could scrap it and come out ahead and I could just pull in heavier wire if I need more capacity later down the road.

 

[wyliesdiesels]

Ok well you should do fine with 50a or 60a.

Unfortunately, al wire isnt worth much and even bare stripped cu wire has come down in price around here anyway. (I use to get $2-$2.2/lb for Cu; its now at $1.5/lb. junk yard said metal prices are down cause no one is buying)

If u do want to go bigger u could go with 1/0 AL and a 90a breaker to keep the VD down to 3%.

 

[Speedway]

So I have the 2" conduit trenched in and was thinking about bushing down to 1-1/4" out of the top of the 90's at the house and barn.
The only reason is to keep the junction box size down to an 8x8x4 on the side of the house, will this be an issue or should I stick with a 12x12x6 box?

Also, how long should the wiring extend outside of the boxes for the splices? The only thing I could find in the NEC book was 6" from where the cable exits the conduit inside the box, does this sound correct? Doesn't seem like much to work with...

I would also like to exit the rear of the boxes to enter the house and barn, I know I have seen this done in commercial settings but not sure how to go about it on residential.

Thanks for the help

 

[Speedway]

I know the answers are in the code book somewhere (or maybe not?) but I don't know whether to sh!t or go blind trying to find them.
I have tried finding installation instructions/ guidelines for the junction boxes without any luck.

Any help at all would be appreciated on this.

 

[wyliesdiesels]

Youre looking for conduit fill tables.

Typicaly u want to size the junction box @ 8x the conduit size.

I would keep the conduit @ 2"

 

[pattenp]

You don't need to use a box as big as eight times the 2" conduit. That would be a 16" box. Read NEC 314.28 (a) (2) & (3). Since 1.25" conduit is the smallest conduit you can use for your wire you can use a box 6 times X 1.25" or 8". The box needs to be permanently marked with what the max number and size of conductors that are permitted.

 

[wyliesdiesels]

You don't need to use a box as big as eight times the 2" conduit. That would be a 16" box. Read NEC 314.28 (a) (2) & (3). Since 1.25" conduit is the smallest conduit you can use for your wire you can use a box 6 times X 1.25" or 8". The box needs to be permanently marked with what the max number and size of conductors that are permitted.

I cant stand small boxes...but thats just me.

 

[pattenp]

I cant stand small boxes...but thats just me.

I can't disagree with that. A 10" or 12" box will do nicely. I just think going 8 times the 2" conduit is a bit too much for his #2 wire if that's what's still being used. Those larger boxes get a little pricey.

 

[Speedway]

Thanks guys.
I guess I'll do a 12" box and 2" conduit up to the box.
I am doing the 2-2-2-4 still, that's why I thought about going smaller on the box and conduit. Other than curb appeal...

So on the free length of wire splice in the box, 300.14 states 6" from where it exits the conduit. Would this apply to my install?

What would be used to get from the rear of the junction box through my band board into the basement?
What is the proper way to mount the box on vinyl siding?

 

[pattenp]

Leave plenty of wire to work with when doing the splices. If you are using a 12" box I would leave no less than 12 inches of wire where it exits the conduit. There is no issue if you need to curl up the wire to push it back into the box. Too long is better than too short.

The mounting of the box can be done by using some support strips of PVC board in the low spots of the siding and boring a hole large enough to slip a ****** from the back of the box through the siding and the band board. Then screw directly through the back of the box though the support strips into the band board. Weather seal around the ****** to the siding the best you can with electrical putty. This is just a suggestion since I can't actually see what you are dealing with.

 

[Speedway]

Leave plenty of wire to work with when doing the splices. If you are using a 12" box I would leave no less than 12 inches of wire where it exits the conduit. There is no issue if you need to curl up the wire to push it back into the box. Too long is better than too short.

The mounting of the box can be done by using some support strips of PVC board in the low spots of the siding and boring a hole large enough to slip a ****** from the back of the box through the siding and the band board. Then screw directly through the back of the box though the support strips into the band board. Weather seal around the ****** to the siding the best you can with electrical putty. This is just a suggestion since I can't actually see what you are dealing with.

Perfect, thank you!

 

[wyliesdiesels]

Yeah nothing like having too little wire to work with when splicing. It can be a nightmare.

To me reducing conduit looks silly and theres no point in the little extra work a few feet away from the box

 

[pattenp]

Yeah nothing like having too little wire to work with when splicing. It can be a nightmare.

To me reducing conduit looks silly and theres no point in the little extra work a few feet away from the box

You lost me with the reduced conduit comment.

 

[wyliesdiesels]

You lost me with the reduced conduit comment.

The OP talked about reducing from 2" to 1 1/4" in #11.

 

[Speedway]

Just wanted to say thanks again!
Waited 2 weeks for the only electric inspector in my county office to show up. It has rained hard here for days, my trench was pretty much a river but I passed with flying colors yesterday.