sub panel power

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  #1  
Old 06-04-13, 06:13 PM
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sub panel power

Hi, To try and keep a long story short I am adding 100a sub service in a new building on existing 200a powered property. The new service will never require more than 100a so I was going to come off the existing home with alum. URD 2-2-2-4 to my new panel , well that's changed but the pole in our property which is about 150' away from the new building has a 200a breaker panel under the can. I didnt' open the box yet but know it is copper. My question is could I still use the already purchased URD wire and lug it to the copper coming off the 200a breaker? By the way I have more than enough amps to add this new power take-a way. as far as usage in either building (just to clear that up). Thanks
 
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Old 06-04-13, 06:43 PM
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I'm just a little confused......you have a 200 amp service on a pole in your front yard. There is a single 200 breaker in it ? What is it feeding now ?

To add a 100 amp underground cable to that box you would need to connect it to a 100 amp breaker.
 
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Old 06-04-13, 06:48 PM
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Short answer is no. If the box on the pole only has one breaker, and no spaces, you can't use the #2. Here are the options:

1) Install some 4/0-4/0-4/0-2/0 aluminum URD to your new panel from the pole 200 amp breaker. You will need to install some double lugs in the enclosure. You may not put 2 wires under one lug.

2) Mount an outdoor panel, or disconnect, next to the 200 amp panel. Add some double lugs, and feed the panel/disconnect. Then install some 100 amp fuses or breaker and feed the 2-2-2-4 URD off of that. The wire off the 200 amp breaker to the new panel/disconnect, in this case, can be the same size as the feeder going to the the new building, as long as the new panel/disconnect is 25' or less total wire run and it is wired in conduit.
 
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Old 06-05-13, 05:49 PM
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Sorry about the seemingly stupid questions but my wiring has all been from panels inside never the outside in. In my situation the 200a breaker box is right below the can on a pole
like you would find for a mobile home, there isn't enough space under it to add the 100a box I just bought, is it permissible to attach the 100a box to the side of the 200a box with hub connectors and a short piece of tube using the 2-2-2-4 URD in lugs Then off the 100a breaker and go the 200' to the new building?
 
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Old 06-05-13, 05:53 PM
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Or would I just be well off dbl lugging off the 200a breaker all the way to the new building , as I do have a main in the new panel inside the new building.
 
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Old 06-05-13, 07:49 PM
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The answer to your question depends in part on your answer to this question:
you have a 200 amp service on a pole in your front yard. There is a single 200 breaker in it ? What is it feeding now?[/highlight]
 
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Old 06-05-13, 09:08 PM
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Like I said in the first post "an existing home" Explaining a little better its a mobile home with 2 older people in it using very little amps. the service also used to power a second very small mobile home from a 60a breaker in the panel in the main mobile home and also fed a 60a breaker in the main panel for an old shop/barn . the small home and the old shop were disconnected and destroyed the 2 60a breakers were never used again. At any given time neither place the new proposed 100a panel or the existing 200a panel in the home will ever experience usage to exceed maybe 70 amps each at one time. I hope this helps.
 
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Old 06-06-13, 07:21 AM
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So let me get this straight, you want to tap off the LOAD side of your service disconnect with #2 and feed a 100A disconnect next to the main disconnect? Assuming it's done properly, I see nothing wrong with it.
 
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Old 06-06-13, 02:40 PM
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You can either add a 100A breaker next to the 200A breaker at the pole or you can add it in the 200A panel in the existing home. You cannot run feeders rated for 100A off a 200A breaker.

The size of the feeders you need depends in part on the length of the run.

If the load in the new building will be 100A, to keep the voltage drop to less than 3% you will need #1/0 aluminum conductors or #1 copper conductors for the 150' run from the pole to the new structure.

If you want to know what size you'd need from the 200A panel, give us the distance for that run.

You might do well to do a load calculation for the new building.
 
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Old 06-07-13, 05:36 AM
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So I cant run the 100a feeders off the bottom of the 200a service breaker with the existing 200a feeders using 2 hole lugs?
 
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Old 06-07-13, 08:55 AM
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My load calculation for the new building is about 70a . My main question is options to get the power #1- lugging off the service side of the outdoor 200a breaker with the existing 200a service to the mobile home with my 2224 URD to my new service panel close to 200' away? OR #2- adding a 100a breaker box next to the 200a outdoor box, lugging from box to box then on to the new building ? And knowing the amp draw from the existing mobile home is also around 70a.. For other reasons I cant come off the 200a panel in the existing home. I somehow need to come from the outside 200a breaker.
Sorry this is so confusing, its hard when your not here, but all help is appreaceated.
 
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Old 06-07-13, 09:34 AM
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So I cant run the 100a feeders off the bottom of the 200a service breaker with the existing 200a feeders using 2 hole lugs?
The breakers must be sized to protect the wires. If the wires are large enough for 200 amps and the breaker is rated for double lugging yes.
 
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Old 06-07-13, 04:42 PM
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So I cant run the 100a feeders off the bottom of the 200a service breaker with the existing 200a feeders using 2 hole lugs?
No. Think about what you just said. How is a 200A breaker going to protect 100 ampacity rated wires? Besides that, the existing breaker is already fully utilizes; it's protecting the 200 ampacity rated wires going to the house.

The only way you can start the feed for the new building from the location of the 200A service breaker is by installing a second breaker there. You'll need a licensed electrician to do that for you, because the incoming feed will have to be split to feed each breaker, or the existing breaker box will have to be replaced with one that will accept two 240V breakers. Either way, the work involves the feeds from the meter.

My load calculation for the new building is about 70a . My main question is options to get the power #1- lugging off the service side of the outdoor 200a breaker with the existing 200a service to the mobile home with my 2224 URD to my new service panel close to 200' away? OR #2- adding a 100a breaker box next to the 200a outdoor box, lugging from box to box then on to the new building ? And knowing the amp draw from the existing mobile home is also around 70a.. For other reasons I cant come off the 200a panel in the existing home. I somehow need to come from the outside 200a breaker.
You might be allowed to connect a new breaker to the incoming side of the 200A outside breaker at the mobile home. You'd have to ask your permitting office about that.

The proper way is to install the new breaker in the inside panel. I'd install a 70A breaker, BTW. You can still mount a 100A panel with a main breaker in the new building. That will give you lots of breaker spaces, and the 100A main will serve as your required disconnect.

Why would it be difficult to start from the panel?
 
  #14  
Old 06-08-13, 05:59 AM
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I have had everything to do just that and know how to do it, at the last minute the older lady (family) doesn't always think right and decided it would cause a fire, no matter who installed it. I had everything to do it even the trench dug!
Thats when I started looking at alternatives but know little about coming off a pole. I knew the existing breaker is all ready protecting 200a but thought if the 200& 100a feeders coming off the bottom would never exceed 200a Ide be ok. So what your saying is its a no go unless I come off the meter? Thanks for your help.
 
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Old 06-08-13, 06:21 AM
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I'm not questioning you as much as wanting to learn something. How can coming off the bottom of the 200a service breaker on the pole with dbl lugs with my 100a feeders which is going to my new 100 service panel (main breakered) using about 70a. and the 200a feeders on the lugs(at the pole) still feeding the existing panel (no main breaker)in the existing mobile home using about 70a. I keep wanting to think it would be the same as coming off the existing panel full of breakers with a 100a breaker to feed my new panel.
 
  #16  
Old 06-08-13, 07:01 AM
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It doesn't matter if you exceed 200 amps with the two feeders, what you are doing is protecting the wire with the breaker. If you ran the #2 off a 200 amp breaker it would be quite over-fused and could start a fire! You need to protect the #2 amp wire with a 100 amp overcurrent device (breaker or fuses).

Coming off the pole is a fairly good option, it is just how you want/can do it. If you can install double lugs in the 200 breaker, you could then add a 100 amp fused disconnect next to that, and run your new feed.

If you can't add the lugs, you could install a 200 amp outdoor panel with feed through lugs Like this: Square D by Schneider Electric Homeline 200 Amp 8-Space 16-Circuit Outdoor Main Breaker Load Center with Feed-Thru Lugs-HOM816M200FTRB at The Home Depot Interrupt the 200 amp feeder going to the existing house. Run a new short feeder off the existing 200 amp breaker to the new outdoor panel. Then feed the 200 amp feeder to the house off the feed through lugs. All you need then it to use a plug in 100 amp breaker for your new feeder.

To mount all this equipment, just sink a 4x4 post and run some 2x between the existing pole and the new 4x4.

I don't think you can't really come off the meter as you would have 300 amps available, and the meter is likely only rated 200 amps.
 
  #17  
Old 06-08-13, 07:18 AM
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Run a new short feeder off the existing 200 amp breaker to the new outdoor panel. Then feed the 200 amp feeder to the house off the feed through lugs. All you need then it to use a plug in 100 amp breaker for your new feeder.
I like this solution with an exception. This solution is running the power through the existing 200 amp breaker and using that power to feed the new 200 amp main breaker in the new subpanel. I would suggest removing the existing 200 amp main breaker and replacing it with this new 200 amp main breaker panel. The 200 amp main breaker would still protect the 200 amp feeder to the home and would also provide space to add the 100 amp breaker to feed the new building. The 200 amp feeder to the home would be connected to the feed-through lugs.

My option, however, will require feeding the new 200 amp main breaker panel directly from the meter. I think TI was trying to avoid that with his solution.
 
  #18  
Old 06-08-13, 11:05 AM
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I understand and like the idea of the adding a 200a panel next to it then adding my 100a breaker in that panel. That should solve my puzzle. thanks alot
 
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