# Garage electrical, subpanel, couple of questions



## Highbeam (Jan 9, 2012)

I just set the 100 amp siemens subpanel in my new barn this weekend. My setup goes like this:

1) 200 amp house panel, 60 amp breaker for barn.
 2) 6/3 with ground romex to the outside wall of the house.
 3) Transition to 1.5" conduit with THWN-2, same wire sizes and copper. 
4) 24" cover over conduit underground to barn.
 5) Conduit through slab to base of subpanel and into the 100 amp breaker of the subpanel(acts as a disconnect). 

I put in two ground rods at the subpanel and tied them to the ground bar of the subpanel with #4 bare copper. 

On the subpanel I removed the tie bar connecting the neutral and ground bars. I drove in the green screw which ties the ground bar to the panel.

1) Do I run the 10 gauge THWN ground wire from the house to the neutral bar or the ground bar in the subpanel? I assume ground bar but then the neutral will be bonded via the house panel.

2) Where the conduit ends at the house I used a 30 cubic inch LB. I made my splice inside the LB using wirenuts. I've never wire nutted #6 wires and I'm not real happy with how they work. Is this standard practice?

3) The LB is against the house with the back opening poking through the siding to the inside. Regular wirenuts okay or need I use those silicone filled ones? Is there a better connector for this that is more secure than a wirenut?

4) The 6/3 romex just enters the back of the LB. It is not clamped to the LB in any way. I can see into the LB and see the wirenuts through the big 1.5" opening. Is this okay? How close to the LB must my last staple be?

I will be getting a permit for this but our state inspectors don't answer questions, they just show up and approve/fail.

Thanks for your help folks. Before inspection I will be installing the lighting and outlet circuits. When you buy a permit here the single permit covers the subpanel plus five circuits so I want them installed before inspection.


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## Don2222 (Jan 9, 2012)

Hello 
Nice work. Any Pics?
I know now from my shed electrical wiring that the sub panel needs the ground on the ground buss and must be seperate from the neutral. Yes the ground and neutral must still be bonded together at the main panel. Also what is the LB?


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## Highbeam (Jan 9, 2012)

I took pics but haven't uploaded them. It is pretty exciting stuff.

An LB is an elbow with an opening in the back for conduit and a removable access plate for pulling wire. It's really just a 90 degree bend in conduit with an access door. Normal 90 degree bends are like 18" in radius.


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## Don2222 (Jan 9, 2012)

Highbeam said:
			
		

> I took pics but haven't uploaded them. It is pretty exciting stuff.
> 
> An LB is an elbow with an opening in the back for conduit and a removable access plate for pulling wire. It's really just a 90 degree bend in conduit with an access door. Normal 90 degree bends are like 18" in radius.



Yes, It sure is fun stuff. I finally finished installing the 10th AC outlet Sunday. Glad it is done though!! LOL

Yes, I purchased my LBs at Home Depot. I did not know what they called them!! LOL

I have PVC into the ground and then used 10-3 UF-B so no more PVC was needed. I put in 14-3 UF-B for the light switch in the house, Telephone wire, Alarm Wire, Cable TV wire. The Wi-Fi works fine out there. So I am all set. 

The 10-3 UF-B into the house goes right into the main panel so no extra connections. That was not easy since it was 30 feet to the house and then another 42 feet to the other end where the main panel is!! So I bought 150 feet of 10-3 and returned the left over back to Lowes and they took it back I used 95 feet all together.

This wire is so heavy that splicing it may not be good unless you have special connectors!

Here is a pic of the shed LBs and I have two more on the house. The big one for Power and the small one for communications and data.


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## semipro (Jan 10, 2012)

I thought that sub panels required floating grounds per code??  
That is, a ground wire must be run between the sub and main panels and there should be no separate ground rod for the sub panel.  
Maybe that's only if the sub panel is located within the same structure? 

Disclaimer: I'm no expert on electrical codes.


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## burnham (Jan 10, 2012)

If the inspector sees a splice in an LB he's going to sh*t a twinkie.  Not legal.


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## nate379 (Jan 10, 2012)

Splice in LB is legal, provided the fill volume has not been exceeded.

Here is some good reading that can explain it better than I can:
http://www.ecmag.com/?articleID=6303&fa=article

Here is a calculator to figure volume:
http://www.constructionmonkey.com/calculations/electrical/boxfill.aspx

I use reg marettes but I put them so the opening is facing down.  In case any moisture would get in the LB, it wouldn't be able to sit in the wiring connetion that way.


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## oldspark (Jan 10, 2012)

If I remember correctly you dont need the ground from the house, just a 3 wre feeder and use the grounds you installed.
Dont like wire nuts on #6 wire either, I use split nuts on larger wire but if the wire nut goes on and feels good and solid it should be OK.
Not sure about your LB thing, maybe a picture will help.
Make sure the people giving advice on here know what you are doing, I dont like giving advice as some times things get misunderstood. On both ends.


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## Highbeam (Jan 10, 2012)

Awesome calculator Nate. My LB is just barely too small with the added complexity that it is considered a "wet location" since it is outside. Yes, you can splice in an LB. 

I went ahead and bought the 8x8x4 junction box to place inside the home and attach to the conduit stub sticking into the wall from outside. It looks just like Don's picture from the outside. It is going to be pretty ugly since the distance between the wall side of the LB and the  back of box is about 2" for a 3/4" thick wall. Either the LB will have to be pulled away from the wall or the interior box will stick into the room. 

I will use the splice blocks which work like a terminal lug to clamp down each end of the splice into a common block of metal. Then slip a piece of shrink wrap over the connection. Maybe tape at first until the inspector buys it off. 

You must run 2 hots, 1 neutral, and one ground to the subpanel in a different building. The ground is really small, only a #10 is required for a 60 amp circuit. In the panel the neutral is not bonded to the ground, the ground bars, or the panel. The subpanel requires its own ground rods. It will be fun to wire the circuits to the subpanel since  I have to keep the neutrals together on one side of the panel and the grounds together on the other side, each has its own bar. When you install a subpanel in the same building as the main panel the rules are different.


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## oldspark (Jan 10, 2012)

Do you have any metalic connections between the building and where the main panel is?


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## Highbeam (Jan 10, 2012)

None. The subpanel is metal and then immediately into PVC to this splice box (grounded) and then a continuous romex run to the main panel which is metal and grounded.


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## oldspark (Jan 10, 2012)

You dont need the ground but I would intall it anyway, 3 wre feed is still legal for that type of install. I have a web site with some good pictures would you like them or are you set.


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## semipro (Jan 10, 2012)

oldspark said:
			
		

> You dont need the ground but I would intall it anyway, 3 wre feed is still legal for that type of install. I have a web site with some good pictures would you like them or are you set.



I think the ground is now required per NEC Article 250.  It didn't used to be.


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## oldspark (Jan 10, 2012)

Semipro said:
			
		

> oldspark said:
> 
> 
> 
> ...


 Very well could be, my info might be outdated, I think its a good idea anyway, never know you are going to do down the road.


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## semipro (Jan 10, 2012)

Highbeam said:
			
		

> The subpanel requires its own ground rods. It will be fun to wire the circuits to the subpanel since  I have to keep the neutrals together on one side of the panel and the grounds together on the other side, each has its own bar. When you install a subpanel in the same building as the main panel the rules are different.



Good to know.  I'm working on building a garage now and would like to tie in the foundation re-bar as a ground (bonded to a ground rod).   
A dedicated grounding system at the outbuilding makes sense to me but sometimes I don't understand the reasoning behind code requirements.


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## nate379 (Jan 10, 2012)

Highbeam, what is the cu in of your lb connector?

You used #6 wire and #10 ground.  From what I understand that would be 6 #6 and 1 #10 conductors in the LB. (ground is only counted as one).  Now bear in mind I am NOT an electrician, so I might not be correct with that calculation.

That works out to 32.5 cu in.  I'd imagine it would take quite a large LB to meet that.


I'm really curious since when I put in a storage shed last year I used an LB out of my garage wall and into the shed.  From my panel in the garage to the LB is 10/3 Romex and once outside it goes to 10/3 UF wire, until the shed where it's back to 10/3 Romex.

I had went over what I was doing with an electrician and was told it was fine, he had made no mention of box fill and I had no idea about it either until now when I was looking in the NEC.

I used 1.25 or 1.5".  There was plenty of room to make my splices and only reason I went that large was I ran a 3/4" air line from the shed to the garage (compressor is in the shed) so I needed conduit large enough to run that.  I figured that having the air line conduit and the wiring one match in size it would look better.


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## Highbeam (Jan 11, 2012)

The standard 1.5" LB from home depot was 30 or 31 cubic inches and not the 32.5 required. Really close. I don't mind using a big box inside for the splice since that will allow me to leave plenty of slack and extra wire for future changes. 

10 gauge wire requires very little volume for the connections. You could have run the UF the whole way since once inside and out of conduit UF becomes NM. It's just a bugger to work with that thick insulation jacket.


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## Hogwildz (Jan 11, 2012)

I ran a sub to my garage for the garage and my addition. The only thing I remember is sub panels call for Arc fault breakers. They ain't cheap either. The White wires are a pain in the ass as they are coiled, and take up lots of space in the panel.


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## nate379 (Jan 11, 2012)

Hogwildz that may be a local code, but that is not required by NEC.  The code version we use here just requires arc fault for bedrooms.

Highbeam a few years ago I had been told by a pro electrician that UF couldn't be used inside and also couldn't be run in conduit.  That was some of the reason I ran my wires like I did.  I later found out that he was full of crap, but that was after I had put in the wiring for my shed.  I actually trenched in the wire and a conduit for my air line almost 2 years before I built the shed.  I did that the first year I was in the house, before I hauled in several hundred yards of topsoil for the yard or paved the driveway.

It wouldn't have been much hassle on the shed side since the panel is just a few feet from where the wire enters, but on the garage side, the panel is on the oposite wall.  I had to snake a wire down from the attic into the panel, then across the attic and down the exterior wall out into the LB.  I used something close to 50ft of wire all said and done.  It was a pain even with "thick" 10/3 Romex, probably near impossible with UF wire!


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## Don2222 (Jan 11, 2012)

NATE379 said:
			
		

> Hogwildz that may be a local code, but that is not required by NEC.  The code version we use here just requires arc fault for bedrooms.
> 
> Highbeam a few years ago I had been told by a pro electrician that UF couldn't be used inside and also couldn't be run in conduit.  That was some of the reason I ran my wires like I did.  I later found out that he was full of crap, but that was after I had put in the wiring for my shed.  I actually trenched in the wire and a conduit for my air line almost 2 years before I built the shed.  I did that the first year I was in the house, before I hauled in several hundred yards of topsoil for the yard or paved the driveway.
> 
> It wouldn't have been much hassle on the shed side since the panel is just a few feet from where the wire enters, but on the garage side, the panel is on the oposite wall.  I had to snake a wire down from the attic into the panel, then across the attic and down the exterior wall out into the LB.  I used something close to 50ft of wire all said and done.  It was a pain even with "thick" 10/3 Romex, probably near impossible with UF wire!



I used 95 feet of 10/3 UF-B and had to wrestle it down an in!! It was a pain but worth it!!


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## Highbeam (Jan 12, 2012)

Okay so the junction box is in and the splices made. I used a pretty big 8x8x4" metal box and then the tootsie roll looking splice blocks from home depot for the splice covered by a thick piece of shrink wrap on each one. I used my stove lighter to shrink the shrink wrap and it worked but I sure wish I would have used a small torch. I then landed all the wires on the subpanel and set my first 20 amp circuit breaker in place. Not sure what it will power but I just had to put one in before adding the cover panel. 

Everything outside was covered in ice/frost since it was about 26 degrees outside in our wet environment and of course I'm doing everything by headlamp light since it gets dark here by 5pm. 

Arc faults are still only required for bedrooms in my state. I had to use one for a bedroom circuit addition a couple of years ago. The breakers are very expensive, like ten times the cost of a regular one. I was also worried about nuisance trips with it but the only problem has been my fat fingers accidentally tripping the test button while feeling breakers for heat.

Thanks for your help guys.


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