Is this setup good for 100A garage panel?

[JasonF]

Was just hoping you guys could look over my plans to run service to my new pole building that is approx 200ft from my house.

Plan is to put a 100A sub panel in the new garage and feed it with #4 copper THHN wire buried in conduit. Power will be supplied from a 90A breaker inside my homes panel. I plan on running 4 wires (3) #4 & (1) #8 ground) inside 2" sched 40 conduit 18-24" underground along with a grounding rod at the garage. I then would like to bury the conduit in 6" of dirt and then run my Cat/5 wire in 1" conduit along with my natural gas service.
Does this look ok? I will be pulling a permit and contacting the local inspector, just want to sound like I know what I'm doing first.

Couple questions I have are:
Can my (3) #4 wires coming from the house all be black and then taped at the ends with colored tape?
Does the Sched 40 PVC need to run all the way to each electrical box or does it only have to feed wires into the wall of each structure were they then can be run without conduit?

 

[bill in in]

By code in most areas you can't use another ground rod at the out building, that is what the ground conductor is for. Also there is an issue that doesn't seem to come up often about running the service for a building through another building without permeso of AHJ. Rethink your ground conductor size....

You are close to voltage drop issues if you really are going to use the full 90A.

You can paint or tape wires for Identification.

Wires need mechanical protection. Are you going to finish the walls and with what? I would conduit all the way because splicing to a cable wouldn't be a better solution.

 

[Cougar]

By code in most areas you can't use another ground rod at the out building, that is what the ground conductor is for. Also there is an issue that doesn't seem to come up often about running the service for a building through another building without permeso of AHJ. Rethink your ground conductor size....

You are close to voltage drop issues if you really are going to use the full 90A.

You can paint or tape wires for Identification.

Wires need mechanical protection. Are you going to finish the walls and with what? I would conduit all the way because splicing to a cable wouldn't be a better solution.

Why wouldn't they allow a ground rod at the sub panel?
This area they are required. Have to keep the neutral and ground separate in the sub panel.

 

[Stuart in MN]

Unless the local inspector doesn't understand NEC 250 (or for some reason they have some sort of local regulation against it) there should be no problem with having a ground rod at the subpanel, IF it's connected to the ground conductor from the main panel, and the ground and neutral are separate in the subpanel.

If you are using THHN/THWN conductors they have to be in conduit all the way to the respective panels. Also note it needs to have the THWN marking to show it's suitable for use in buried conduit, but most if not all such wire has both THHN and THWN ratings these days.

 

[pattenp]

NEC requires a grounding electrode at detached structures that are served power from another building. Usually due to the low resistance requirement by the NEC for 1 grounding electrode it's common practice to drive 2 ground rods. The rods need to be set at least 6 feet apart from one another. As stated the neutral is isolated from the ground at the sub-panel

Edit:For 200ft. I'd use 2/0-2/0-2/0-1 Al Mobile Home Feeder. #4 Cu is a little undersized for the distance for a 90A feed.

 

[JasonF]

Unless the local inspector doesn't understand NEC 250 (or for some reason they have some sort of local regulation against it) there should be no problem with having a ground rod at the subpanel, IF it's connected to the ground conductor from the main panel, and the ground and neutral are separate in the subpanel.

If you are using THHN/THWN conductors they have to be in conduit all the way to the respective panels. Also note it needs to have the THWN marking to show it's suitable for use in buried conduit, but most if not all such wire has both THHN and THWN ratings these days.

Thanks for the input.
I was also under that impression that a grounding rod was required in my area but I will check witht the inspector for sure. So just to clarify are you saying that the wire must be marked THWN to be buried in conduit while the THHN can not be used for my purpose if its not dual marked?

 

[JasonF]

Edit:For 200ft. I'd use 2/0-2/0-2/0-1 Al Mobile Home Feeder. #4 Cu is a little undersized for the distance for a 90A feed.

I was going with the copper just for the smaller sizing and the ease of pulling such a long distance. If I decide to stay with copper could it just go down to an 80A breaker at my home panel or possibly step up to #3?

What do I have to to do differently if I run Al? I thing I remember reading somewhere that the Al ends required some sort of coating?

I am also curious to know what the formula is for wire sizing and distance? I see that 2/O has been recommended but looking at this chart it looks like I could go with #1 or 1/0 Al as well? Just trying to educate myself.
http://www.cerrowire.com/ampacity-charts


Garage will have 60gal Air compressor (22A), 2 post lift (21A), rarely used Arc welder (50A) and the usual lights/outlets (20A) so I should be able to get by with less than 90A if necessary.

 

[pattenp]

There are online voltage drop calculators you can use to figure the wire size needed. You need to estimate the max load you may have and size the feed at 125% of the estimated max load. The reason I suggested 2/0 MHF is it is usually readily available. The odd sizes of wire such as #1/0 and #3 are sometimes hard to find and need to be ordered. Aluminum wire today in most cases does not require antioxidant paste on the terminations unless recommended by the wire manufacturer. For 200', the aluminum will cost you a lot less than copper.

Voltage drop calculator: http://www.nooutage.com/vdrop.htm

 

[Stuart in MN]

So just to clarify are you saying that the wire must be marked THWN to be buried in conduit while the THHN can not be used for my purpose if its not dual marked?

Yes. The 'W' in THWN means it's approved for use in wet areas, and an underground conduit is considered a wet area. However, most wire these days is dual rated THHN/THWN so it's usually not a big deal - just make sure the wire is marked correctly when you buy it.

edit: Using the voltage drop calculator posted above, plug in 3% voltage drop, 240vac single phase, 200 feet and 90 amps, and it says #2 copper or #1/0 aluminum. Larger sizes will work, of course, but you'll have to check with your local supplier on pricing - if they have a larger size in stock that's less expensive than ordering the smaller size, go for it.

Note that the mobile home feeder MHF cable is direct bury so you don't need conduit, except for sleeves at either end where the wire comes up out of the ground and goes into the structures. The flip side of using direct bury wire is it has less protection from damage, but that's a minor issue as long as it's installed at the correct depth.

 

[pattenp]

MHF is direct bury but it can be run in conduit underground for added protection.

 

[JasonF]

This is some great information, thanks for all the help and the links. I just went out and measured to get an exact distance and I'm even further than I thought at 240', that's with a little extra of course. So it looks like it will have to be Al just to keep the cost reasonable.

 

[Aceman]

To know your voltage drop, you must know what your shop loads are.

You would be best served by listing the equipment/lights you plan on having in your pole barn.

 

[tfi racing]

Wow-200+ feet of copper! Must be nice to able to toss around that kind of loot,I'm curious why you would want the ordeal of burying conduit and hooking up rope to a tractor to pull conductors in it,direct burial cable is the way to go for this distance.

 

[JasonF]

To know your voltage drop, you must know what your shop loads are.

You would be best served by listing the equipment/lights you plan on having in your pole barn.

I listed it above but it was towards the bottom of a post here it is. Garage will have 60gal Air compressor (22A), 2 post lift (21A), rarely used Arc welder (50A), 2 (20A) loops for outlets. and some standard fluorescent lighting.

 

[Speedy Petey]

By code in most areas you can't use another ground rod at the out building, that is what the ground conductor is for. Also there is an issue that doesn't seem to come up often about running the service for a building through another building without permeso of AHJ. Rethink your ground conductor size....

Bill, I am wondering where you are getting your (mis)information from. PLEASE be careful when giving advice about electrical work and codes.

The first sentence is COMPLETELY wrong. A grounding electrode is specifically required at a detached structure served by a feeder, and this has NOTHING to do with the required equipment ground run with that feeder. They serve two totally different purposes.

Also, what is wring with a #8 equipment ground for a 90A feeder?

 

[Speedy Petey]

Wow-200+ feet of copper! Must be nice to able to toss around that kind of loot,I'm curious why you would want the ordeal of burying conduit and hooking up rope to a tractor to pull conductors in it,direct burial cable is the way to go for this distance.

If you need a tractor to pull 3- #4 and 1- #8 into 2" conduit you should stick to being an accountant. Those conductors will pretty much walk themselves in.

Also, many areas are not at all conducive to direct burial cable/conductors. Much of my area has such snotty sharp rocks direct burial is not even a consideration.

 

[theoldwizard1]

Note that the mobile home feeder MHF cable is direct bury so you don't need conduit, except for sleeves at either end where the wire comes up out of the ground and goes into the structures.

MHF is direct bury but it can be run in conduit underground for added protection.

Conduit is also required for MHF inside your building.

 

[JasonF]

If you need a tractor to pull 3- #4 and 1- #8 into 2" conduit you should stick to being an accountant. Those conductors will pretty much walk themselves in.

Also, many areas are not at all conducive to direct burial cable/conductors. Much of my area has such snotty sharp rocks direct burial is not even a consideration.

No extra Loot here, wife and kids will just have to go without groceries for a few weeks!
This is were I'm at now, at 240' one way its much cheaper to do the direct bury MHF aluminum but I do have a lot of debris in the ground so I still might have to do conduit. This was why I was considering CU, mostly for the smaller Diamter and ease of pulling but for the cost savings it will have to be Al.

 

[Speedy Petey]

No extra Loot here, wife and kids will just have to go without groceries for a few weeks!
This is were I'm at now, at 240' one way its much cheaper to do the direct bury MHF aluminum but I do have a lot of debris in the ground so I still might have to do conduit. This was why I was considering CU, mostly for the smaller Diamter and ease of pulling but for the cost savings it will have to be Al.

Oh totally. With 2" even 100A MHF cable will pull in no problem. And the $$ savings will be substantial.

 

[JasonF]

Ok, Just searching the Home Improvement sites the only MHF 2/0 or 1/0 Al I could find come in a 500ft spools which is twice as much as I need. I did notice this though as it would be the perfect length, just want to make sure I can use it?
http://www.homedepot.com/p/Southwir...Cable-13105207/202250409?N=5yc1vZc578Z1z10m2k
Its 2/0-2/0-2/0-1 Al SER Service entrance Cable, not sure what SER stands for?

 

[pattenp]

SER is service entrance cable and is approved for above ground use only. Lowe's and HD should sell the MHF in store by the foot.

 

[JasonF]

SER is service entrance cable and is approved for above ground use only. Lowe's and HD should sell the MHF in store by the foot.

Yep just did some reading on SER and found what you said, I come back to delete my post and you beat me to it.

 

[pattenp]

If you can't find 2/0-2/0-2/0-1 MHF locally, contact these folks to what their price is.
http://www.nassauelectrical.com/products/aluminum-urd/urd-2-0-2-0-2-0-1

Look at the drop down list box, they also have 2/0-2/0-1-4

Beware that straight URD cable is not approved for inside installation it is just type USE. MHF is USE/RHW/RHH and is approved to go inside the building.

 

[JasonF]

So one of the local Home Depots has 2/0-2/0-2/0-1 MHF by the foot but it says USE MHF. Does that mean it can't go inside to my exterior mounted panels or is it ok because it's also RHW/RHH?
http://www.homedepot.com/p/Southwir...ice-Entry-Electrical-Cable-28713601/202316460

I'm going to check prices at the local supply house on Monday too.

 

[pattenp]

That wire is Mobile Home Feeder (MHF) so it carries the RWH/RHH ratings, it will be stamped on the wire. That wire is okay to be installed inside. But as stated earlier it needs to be in conduit where exposed outside and also in conduit when installed inside the building.

So one of the local Home Depots has 2/0-2/0-2/0-1 MHF by the foot but it says USE MHF. Does that mean it can't go inside to my exterior mounted panels or is it ok because it's also RHW/RHH?
http://www.homedepot.com/p/Southwir...ice-Entry-Electrical-Cable-28713601/202316460

I'm going to check prices at the local supply house on Monday too.

 

[FFRKing]

I ordered my wire from here.
http://www.wireandcabletogo.com/Underground-Secondary-Distribution-Cable/
Best price I could find anywhere. I combined my order with a friends and qualified for free shipping so I don't know what that would be.
2/0,2/0,2/0, #1 is $2.27/ft.

Chris

 

[pattenp]

The wire you linked to is not MHF, it's URD secondary distribution cable and is not allowed inside the structure because it's listed only as USE-2.

I ordered my wire from here.
http://www.wireandcabletogo.com/Underground-Secondary-Distribution-Cable/
Best price I could find anywhere. I combined my order with a friends and qualified for free shipping so I don't know what that would be.
2/0,2/0,2/0, #1 is $2.27/ft.

Chris

 

[Charles (in GA)]

If its got a ground wire that is yellow jacketed, its URD. What you want will be two black wires, one with a white stripe, and one with a green stripe.

Markings on MHF look like this:

Charles

 

[Charles (in GA)]

So one of the local Home Depots has 2/0-2/0-2/0-1 MHF by the foot but it says USE MHF. Does that mean it can't go inside to my exterior mounted panels or is it ok because it's also RHW/RHH?
http://www.homedepot.com/p/Southwir...ice-Entry-Electrical-Cable-28713601/202316460

I'm going to check prices at the local supply house on Monday too.

Oddly, and incorrectly, the HD specs, if you scroll the screen down, says NO to wet location use. It is, in fact, suitable for wet locations, as evidenced by the RHW rating.

Charles

 

[Charles (in GA)]

The wire you linked to is not MHF, it's URD secondary distribution cable and is not allowed inside the structure because it's listed only as USE-2.

In other words, it is not fire resistant. Code very clearly says it cannot be used inside an building, and cannot even be used above ground except to junction it to another wire to enter the building.

Charles

 

[JasonF]

The wire you linked to is not MHF, it's URD secondary distribution cable and is not allowed inside the structure because it's listed only as USE-2.

In other words, it is not fire resistant. Code very clearly says it cannot be used inside an building, and cannot even be used above ground except to junction it to another wire to enter the building.

Charles

More excellent info, I've learned a ton! Thanks to everyone for all the input.

 

[JasonF]

Just talked to my inspector and he was onboard with the plans to bury 2/0 MHF aluminum. I just have to put and outlet and a light in at the sub panel somewhere. He seemed pretty laid back and said I seemed to have it all figured out already.

 

[JasonF]

I have come up with another question. When attaching the new 2/0 Al wire into my main panel what is the best way to land the large neutral and ground wires? I have a SD Homeline main panel and I see they make a neutral lug kit but it only goes up to a 1/0 wire size. I do see some other brand lug kits that go larger, what are the odds these would work?
And do I need the same neutral lug kit to land the ground or is there a different ground lug kit for that?

 

[pattenp]

This is the lug you need.
http://www.homedepot.com/p/Square-D...Auxiliary-Neutral-Lug-Kit-LK100ANCP/100115933

Same type lug can be used for the ground.



*

 

[JasonF]

This is the lug you need.
http://www.homedepot.com/p/Square-D...Auxiliary-Neutral-Lug-Kit-LK100ANCP/100115933

Same type lug can be used for the ground.



*

Thank You, I don't know how I missed it in my searching.

 

[Badasssapper67]

Just curious, where you live how far do you have to bury that wire?

 

[JasonF]

Just curious, where you live how far do you have to bury that wire?

I putting the trench in now but its 24" direct buried and 18" in conduit.

 

[bullnerd]

I'm not an electrician, but I was on my utility companies website looking for some info on running to a pole and found a bunch of info on how they want to see it done. Including descriptions and diagrams. How far below grade, two ground rods and distance between, etc... maybe you can find something of use there.

BTW, can someone answer Jasons other questions? Gas and com wires in same trench? One trench over the other?

This sounds like just what I need.

 

[JasonF]

I'm not an electrician, but I was on my utility companies website looking for some info on running to a pole and found a bunch of info on how they want to see it done. Including descriptions and diagrams. How far below grade, two ground rods and distance between, etc... maybe you can find something of use there.

BTW, can someone answer Jasons other questions? Gas and com wires in same trench? One trench over the other?

This sounds like just what I need.

Just got off the phone with both the electrical inspector and mechanical inspector, both had no issues with putting both in the same trench. The mechanical inspector just wanted some division so we agreed on 8-10 inches of fill between the two. I did find it odd that he did say the gas line only needed to be a minimum of 8" in the ground,, don't think I could do that with a clear conscience. Will probably do the electrical 2-3ft down with the gas at 18".

 

[bullnerd]

thanks