# Sub Panel Main Lug Load Center - Single Phase ?



## Roy Rowlett (Apr 14, 2009)

I am running a subpanel to a workshop near my house. I will run it from a 60amp breaker in my main panel, which is 200amp. I want to have at least 12 positions in my subpanel. I have seen a main breaker panel rated at 100amp, but it has a 100amp main breaker already installed. I found a main lug panel at Home Depot, but I am not sure if it will work for me. I need to have 220v capability. The description of the panel from Home Depot is:
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Homeline 125 amp main lug load center. Single phase, indoor, NEMA Type 1 enclosure. Convertible to main breaker with a QOM1 main breaker. 20 spaces using Homeline breakers. Overhead/Underground feed. 2.5 inch maximum knock-out in both the top and bottom endwalls. Aluminum bus. 120/240 Vac. 22,000 maximum short circuit current rating. Combination cover factory included.
**************************************************
In my ignorance, I do not understand what the implication of "single phase" is. I need to run 6-3 with ground, which will have two 110v hot feeds, along with the common and gnd.
Please tell me if "single phase only" would restrict my usage.
Thanks


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## nap (Dec 4, 2007)

single phase is what a typical house uses. That would be the 2 hots, the neutral (common) and the ground for safety sake.

3 phase has one more hot. How we get from single to 3 phase and only add one wire is a bit of explanation and if you want it, we'll go there. Just say so.


either of the panels you listed will have 240 volts available as long as you run the 2 hots and neutral.


before you go and buy stuff, hang on for a lot of advice. It's late and I'm tired so I don't trust myself enough to give you great advice at the moment. If somebody doesn't pick this back up by tomorrow, I'll be back.


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## frenchelectrican (Apr 12, 2006)

Roy Rowlett said:


> I am running a subpanel to a workshop near my house. I will run it from a 60amp breaker in my main panel, which is 200amp. I want to have at least 12 positions in my subpanel. I have seen a main breaker panel rated at 100amp, but it has a 100amp main breaker already installed. I found a main lug panel at Home Depot, but I am not sure if it will work for me. I need to have 220v capability. The description of the panel from Home Depot is:
> **************************************************
> Homeline 125 amp main lug load center. Single phase, indoor, NEMA Type 1 enclosure. Convertible to main breaker with a QOM1 main breaker. 20 spaces using Homeline breakers. Overhead/Underground feed. 2.5 inch maximum knock-out in both the top and bottom endwalls. Aluminum bus. 120/240 Vac. 22,000 maximum short circuit current rating. Combination cover factory included.
> **************************************************
> ...


 
I will fill in Nap's spot for a while if Nap don't mind it.:whistling2:

Ok let start word " single phase " that mean this is a common power supply useally found majorty of the resdentail and some I say some small commercal locations as well.

It defenined as two hot conductors and netrual and ground and typically the voltage is from 115 to 125 volts line to netrual or 230 to 250 volts line to line.

Yeah there is 120/208 volt single phase but not used very often so we will leave this out for now { found some resdential and commercal locations and pretty common found in larger apartment compex or large condos}

The three phase is actally three hot conductors and some wil use netural and some don't due there are two diffrent system.
I will leave this part out for now it kinda pretty long winded details so genrally it don't cover most DIY items anyway.

Now let get to the chase with load centre you can use the main lug however there is a nice gotcha there is a 6 throw rules on it senice you have this as subpanel at detached building like example workshop or garage { not attached to the house } so you can use them but you will need a 60 amp two pole breaker with breaker tie down { the breaker will work in reverse manner so it will function the same as standard main breaker is } or get a load centre with main breaker belive or not some case it cheaper to get one with main breaker allready installed that will serve as disconnection switch point.

And double check with the load centre to see if have seperated ground bussbar if not you can able get one for few bucks 

Now you will need to run #6-3W/G UF{ copper verison } or run in the conduit { pipe } with THHN conductors { black , red , white and green }

And for burial depth with UF it have to be at least 24 inch deep but with conduit you may get by shallow as 18 inches { only if your local code do allow it } otherwise stay with 24 inches deep as well and my suggest if you going bury the conduit get a second conduit so you can use the second one for phone line or data cable 

If you going with conduit route go with 1 inch I know from my expernice it can use 3/4 inch but not worth it if you have more than two bends there.

And if you are on 2008 NEC code everything on 120 volts must be on GFCI protected { unless stated otherwise by local codes }

Oh yeah you will need two ground rods with #6 bare conductor and the distance between the ground rods are at least 6 feet apart or more.

I will stop right there if you don't understand or need more question just holler one of the members in here will help you with more details as you need to.

Merci,Marc


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## Stubbie (Jan 7, 2007)

Marc covered it pretty good...to summarize..

Virtually all residential panels (load centers) allow 120/240 volt supply. 

4 wire feeder uf or thwn in conduit. If thwn your ground only needs to be a #10 awg copper. Hots need to be #6 awg black or one black one red, a white neutral & green #10 ground.

Direct burial 24" 

PVC conduit 18" to top of pipe

Sch.40 underground sch 80 above for protection....thwn in conduit

Uf needs to be protected with sch.80 where it is subject to damage and until it turns horizontal in the trench. Use a pvc sweep to transition from vertical to horizontal 

Your Detached garage must have at least a 60 amp building disconnect that is *service rated* outside or inside nearest the point of entrance of the feeder....main breaker panel is the easiest way to meet this requirement for 100 amp panels with more than 6 full size spaces. I prefer a single enclosure disconnect then feeding an mlo panel from it. This allows you to put the panel anywhere you want instead of being handcuffed to the feeder entrance.

Check to see if sub panel takes slim or tandem breakers, this increases circuit capabilty for 120 volt circuits and in some cases 240 volt circuits.

Some like panels that only take full size breakers. 

Neutral ground seperated at the sub to accomadate 4 wire feeder and to avoid parallel path for neutral current.

2 ground rods, local code may allow one. Use #6 solid copper for the grounding conductor/s from ground bar in sub panel to ground rod clamp. Use a listed ground rod clamp sometimes called an acorn










local codes may require separation of different utilities in the same trench. Water goes in the bottom everything else above if seperation is required in most cases.


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## Roy Rowlett (Apr 14, 2009)

*I think this confirms that my plan will work*

Thanks for the responses. Based on what I am hearing, here is what I am planning:

1. Put a 60amp breaker in my main panel.

2. Run internal 6-3 w/gnd to a non-fused disconnect box on the outside of my main house. This run inside the main house is about 75 ft.

3. Run THWN (THHN if permissable), (R,B,W,gnd) in conduit at least 18" below ground (probably in 1" - 1.5 " conduit, for ease of pulling wires) from the disconnect box for the 30ft underground to my workshop and to the panel. I will put this disconnect in so that I can easily isolate the workshop power if necessary, and it allows me to not have to have a continuous run of wire from my main house panel to my workshop subpanel. I will put the THWN inside the workshop in conduit for the 10ft or so from the outside to the panel inside.

4. I will use a 100amp load center (Siemens), with 100 amp main breaker as my subpanel in the workshop. The main breaker in the subpanel will serve as a disconnect only, since the 60amp breaker in the main house panel will limit the current. This makes the "6 throw rule" moot. It has 12 breaker positions. I cannot find a 60amp load center or main lug panel with 12 positions, so my planned usage should be OK, and possibly even safer than using a main lug panel that backfeeds from a 60amp breaker to the other breakers, because with that arrangement, the load side of the 60amp breaker will be hot if I handle it. It does not appear to be any more money with the panel I am going to use. I will make notations inside the subpanel about what I have done.

5. My outlets will be 20amp, lights 15amp, and I will have a 220v outlet on a 30amp breaker. 

6. I will drive a gnd rod outside the workshop and attach that to the same gnd bar in my subpanel that the gnd from the main house ties to. The white common from the main house will be isolated from the gnd wire.

Have I left anything out? I'm not that worried about code, just safety and function. I don't let those inspector guys on my property. :wink:


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## Stubbie (Jan 7, 2007)

Yeah that's pretty darn close. Just a few clarifications. Thwn and thhn are going to be one and the same... if you buy new wire. The wire will be essentially dual rated. It must carry the th*w*n in order to be put in conduit underground which is rated wet location (Wet = *w*). so the wire is going to say on the outside jacket both thhn and thwn...probably will have thwn-2 which puts the isulation the same a thhn. None the less must have the w in the insulation code. Don't be surprised to see additional ratings as well.

I like your idea of a disconnect box where your feeder leaves the house this will eliminate bulky splices and JB and considering your wiring method. Be sure it is rated for your feeder. Might check out the Qo200tr by square d. It is a 60 amp disconnect primarily used for air conditioners but is also service rated if upstream OCPD (like yours is present) not exceeding 60 amps 10000 amp rms and ground bar is installed. It is non-fusible and is essentially a Qo double pole breaker case (switch only) without overcurrent protection. Very cost friendly. Common at the big box store


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## Roy Rowlett (Apr 14, 2009)

*Neutral tie strap*

I noticed a neutral tie strap installed in my new Siemens 100amp load center panel that I am going to use as a subpanel. I am assuming that I should remove this strap so that I can keep the neutral from my main house panel and the ground (which includeds the gnd wire from my driven rod outside my workshop) isolated from each other. The Siemens documentation said that if I remove the neutral tie strrap, I will need the lug kit, LKB1. What is this, and what is it for?
http://www2.sea.siemens.com/NR/rdon...BE51-F2D2B2D7F6C1/0/Ultimate_Load_Centers.pdf


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## 220/221 (Oct 9, 2007)

In the Seimans panels you can remove the jumper between the ground/neutral buses and use half for the ground and half for the neutral if you like. (Be sure and bond the _ground_ side to the enclosure)

If you choose to use both halves for your neutral connections you cam install a _ground lug kit_ using a couple of pre tapped holes in the enclosure.


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## Roy Rowlett (Apr 14, 2009)

220/221 said:


> In the Seimans panels you can remove the jumper between the ground/neutral buses and use half for the ground and half for the neutral if you like. (Be sure and bond the _ground_ side to the enclosure)
> 
> If you choose to use both halves for your neutral connections you cam install a _ground lug kit_ using a couple of pre tapped holes in the enclosure.


Could you explain "bond the ground side to the enclosure"?


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## 220/221 (Oct 9, 2007)

The ground lug bar must be screwed/mechanically conductively attached to the metal can (enclosure).

Some panels come with a zig zag piece that atteches to one hole in the ground bar and to a hole pre tapped in the back of the can.

Other panels come with a screw that screws thru the bar into the can.

In any case, all you need to do it install a short piece of #10 wire to the ground bar and attach it to the can. A self tapping screw into the can will suffice if there is no factory tapped hole.


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## Stubbie (Jan 7, 2007)

This link shows the panel label for a Siemens 125 amp breaker panel.. look at the diagrams on the right of image.... I believe this will be the same as yours. May have to use the magnifier and scroll right due to size of image

http://www2.sea.siemens.com/NR/rdon...-8BD6-78BFECDA6C71/0/G4040L1125CU_4094705.pdf

You need the lug kit in order to use the left neutral bar as an equipment ground bar isolated from the right side neutral bar when you choose to remove the NTL bonding strap. This lug kit is the same as the one you will see at the top of the right had neutral bar. You install the lkb1 kit on the left neutral bar after removing the strap. You then take the green bonding screw and install it thru the hole in the lug and it threads into the metal of the panel. You *do not* put a green screw thru the lug hole on the right hand side . If you do then both bars will be bonded to the metal of the panel and joined electrically. The lug kit doesn't come with a green screw for bonding so this shouldn't be an issue.

So install the ground bar lug kit on the left side bar and only put the green screw in that left side lug to bond it with the metal of the panel.. Your feeder ground will also connect in the screw compression fitting of that same lug if you want.

Personally I wouldn't do this. I would leave the neutral bars as is with bonding strap between them and do not install the green screw in anything. I would purchase the equipment ground bar kits (not the lug kit lbk1) and install them on the left and right side of the panel into the factory swaged holes ( look at the diagram).

This gives me neutral connections on both sides and ground connections on both sides. Much better IMO. The green bonding screw is then just left unused because the ground bars are mounted to the metal and do not sit on insulator stand offs like the neutral bars where the screw is needed to bond to the metal. 

The place you buy the panel should carry the ground bar kits.


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## Roy Rowlett (Apr 14, 2009)

*Ground straps connected via cabinet?*



Stubbie said:


> This link shows the panel label for a Siemens 125 amp breaker panel.. look at the diagrams on the right of image.... I believe this will be the same as yours. May have to use the magnifier and scroll right due to size of image
> 
> http://www2.sea.siemens.com/NR/rdon...-8BD6-78BFECDA6C71/0/G4040L1125CU_4094705.pdf
> 
> ...


*************************************************
OK, I may leave the cabinet as is and buy the two add on ground bars, as you suggested.
If I connect the ground wire that comes from my driven rod outside the new shop to one of the added ground bars, will the other added ground bar be OK since it is connected electrically through the cabinet? or should I connect the two ground bars with a ground wire?


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## spark plug (May 5, 2009)

*Elaborating on difference bet. Ground & Neutral!*



220/221 said:


> The ground lug bar must be screwed/mechanically conductively attached to the metal can (enclosure).
> 
> Some panels come with a zig zag piece that atteches to one hole in the ground bar and to a hole pre tapped in the back of the can.
> 
> ...


Just to enhance 220/221s point. Since this (your new panel) is a SUB panel, the NEUTRAL lead can not be GROUNDED. Meaning, that the WHITE wire may not be attached to the body of the panel or the equipment ground wires. A function that MUST be performed in the (service) MAIN panel ONLY! (Now more than ever):yes::no::drinkon't Drink and Drive!!!


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## Stubbie (Jan 7, 2007)

Roy Rowlett said:


> *************************************************
> OK, I may leave the cabinet as is and buy the two add on ground bars, as you suggested.
> If I connect the ground wire that comes from my driven rod outside the new shop to one of the added ground bars, will the other added ground bar be OK since it is connected electrically through the cabinet? Or should I connect the two ground bars with a ground wire?


No need to connect the two ground bars with a wire ... the metal of the panel will be all that is needed to bond them together. Just connect your grounding conductor from the ground rod to either ground bar in the panel. All ground bars will accept up to #4 awg with out having to add any oversize lugs to them. Your feeder ground will be 10 awg and it also can be connected to either ground bar. The ground bar kits for Siemens panels are common at the big box stores. Be sure it is a Siemens ground bar or it will not match the mounting holes in the panel.

It will look like this


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## Stubbie (Jan 7, 2007)

Roy

I want to be sure you understand the grounding electrode system and the equipment ground system. They are not the same thing.

The ground rod is connected to the panel for protection of property (your electrical equipment) from high voltage events like lightning and utility power surges. It has nothing to do with the equipment grounds in the branch circuits or the feeder ground.

The equipment grounds are for human safety and bond all metal that is likely to become energized in a ground fault to an ungrounded conductor. This creates a low impedance/resistance path we call the effective ground fault path back to the transformer.. not to earth or any ground rod. The resistance to earth is too high to allow enough current to flow thru a breaker to trip on fault. Fault current must be able to get back to the transformer in order for the resistance to be low enough to get lots of amps (current) to flow thru the breaker to trip it.

As you know we bond the neutral and equipment grounds at the neutral bar in the main panel where the main disconnect for the dwelling is located. We have to do this because there is only one *low* impedance/resistance path back to the transformer at that point. That is the service neutral. I've made a diagram to show this relationship with the grounding electrodes and the equipments grounds as I've shown below..... hope it helps if you need clarification.


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## kbsparky (Sep 11, 2008)

Stubbie said:


> Yeah that's pretty darn close. Just a few clarifications. Thwn and thhn are going to be one and the same... if you buy new wire. The wire will be essentially dual rated. It must carry the th*w*n in order to be put in conduit underground which is rated wet location (Wet = *w*). so the wire is going to say on the outside jacket both thhn and thwn...probably will have thwn-2 which puts the isulation the same a thhn. None the less must have the w in the insulation code. Don't be surprised to see additional ratings as well.
> 
> I like your idea of a disconnect box where your feeder leaves the house this will eliminate bulky splices and JB and considering your wiring method. Be sure it is rated for your feeder. Might check out the Qo200tr by square d. It is a 60 amp disconnect primarily used for air conditioners but is also service rated if upstream OCPD (like yours is present) not exceeding 60 amps 10000 amp rms and ground bar is installed. It is non-fusible and is essentially a Qo double pole breaker case (switch only) without overcurrent protection. Very cost friendly. Common at the big box store


Please note that this disconnect box does not have provisions for connection of the neutral conductor when using a 4-wire feeder such as you have in this scenario. You will have to "wire-nut" the neutral wires, and it will be very crowded inside the enclosure. Some inspector-critters may not like the wire-fill when using #6 conductors. :huh:


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## Roy Rowlett (Apr 14, 2009)

Stubbie said:


> Roy
> 
> I want to be sure you understand the grounding electrode system and the equipment ground system. They are not the same thing.
> 
> ...


***********************************************
Thanks. Just to be sure I have it:
Since the ground in my sub-panel is connected to the ground feed from my main panel, and the main panel common and ground are bonded together in the main panel, then the ground from my sub-panel is electrically the same as the common throughout. There should be no difference of potential between any ground and the common. The path of least resistance from my sub-panel ground to earth is the driven rod at my workshop, therefore it will carry any fault currents to earth. None of this really matters to me as long as I don't see smoke. Just kidding. I know it is important to have it correctly wired.
Thanks again.
_By the way I think it is OK to be scared 1/2 to death twice, as long as its the same half._


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## Stubbie (Jan 7, 2007)

kbsparky said:


> Please note that this disconnect box does not have provisions for connection of the neutral conductor when using a 4-wire feeder such as you have in this scenario. You will have to "wire-nut" the neutral wires, and it will be very crowded inside the enclosure. Some inspector-critters may not like the wire-fill when using #6 conductors. :huh:


Kbsparky does bring up a point I left out, forgot...or was asleep:sleep1:. You will have a splice on the neutral but I never wirenut #6....I use an insulated connector called a splicer (similar to a polaris) for this disconnect... it is tight. It is possible you could be pretty borderline on box fill. There are certainly 'better' disconnects that have provisions for neutral connection. Siemens actually has some knife style (side handle) disconnects you may like better with the neutral provision. I believe the big box may carry these but not sure. I was trying to give a nice disconnect that didn't hurt budget and was good for the job but as kbsparky says it is not wire friendly with #6's and the addition of the neutral splice.

If I am using a junction box to transition #6 wires from cable to thhn/thwn....I never wirenut these big size wires though it is perfectly acceptable. I use power distribution blocks (splice boxes) and install them in the JB. And I install the accessory protective cover over the splice box. I usually use a 6x6x4 metal JB by weigmann.


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## Stubbie (Jan 7, 2007)

> The path of least resistance from my sub-panel ground to earth is the driven rod at my workshop, therefore it will carry any fault currents to earth.


Nope....it will not carry any *fault current* to earth. It will carry current from lightning strikes or power surges to earth...big high voltage events...

Fault current from a single phase fault on a branch circuit returns to the transformer via the equipment grounds and over the service neutral... not to earth...it is not a low resistance path back to the transformer because the current has to go thru dirt to get there...:thumbsup:


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## spark plug (May 5, 2009)

*Debate (continues) about method of splicing Neutral in (outdoor) box!*

Stubbie 10:53AM, #18. I'm certain KB Sparky #16 didn't mean "Wirenutting" literally. I haven't seen someone "Wirenutting" Two #6 wires, yet. My method would be securing the splice with a Burndy "BUG" of the appropriate size, in addition to Rubber tape and plastic insulating tape! (Now more than ever) :yes::no::drinkon't Drink and Drive!!!


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## Stubbie (Jan 7, 2007)

Actually Kbsparky makes a very good point about this disconnect. It ain't got a lot of room.... and it is all at the bottom where the ground bar is. I've discovered a way to use a special connector to make the neutral splice when using #6 and "fit" it all in this disconnect. Problem was I flat forgot to bring that point up. I like the disconnect for those who have a low budget which I do not think was the case with Roy in this thread. It might be better for him to move to a different disconnect with more room and a neutral provision.


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## kbsparky (Sep 11, 2008)

spark plug said:


> Stubbie 10:53AM, #18. I'm certain KB Sparky #16 didn't mean "Wirenutting" literally. I haven't seen someone "Wirenutting" Two #6 wires...


Actually I did. Ideal makes a wirenut suitable for (2)-#6 wires. Some folks call them big blues.


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